OFFICIAL PUBLICATION OF THE CANADIAN ACADEMY OF AUDIOLOGY PUBLICATION OFFICIELLE DE L’ACADÉMIE CANADIENNE D’AUDIOLOGIE
www.canadianaudiology.ca
Vol. 8 No. 3 Revue canadienne d’audition 2013
Articles from the Final Seminars on Audition
Noise Reduction to Achieve Quailty ABR Measurement
Peer Reviewed
Publications Agreement Number 40025049 | ISSN 1718 1860 www.andrewjohnpublishing.com
Message froM the editor-in-Chief |
or the past 28 contributions from Dr. Susan Scollie, Dr. Marlene Begatto and her colleagues at Fyears, Seminars Jo DeLuzio, and Marilyn Reed. As you Western University (the new name of the on Audition has can probably guess from the areas of University of Western Ontario) has been one of my specialty of these people, the seminar written a delightful article on audiological favourite hobbies. started with young children and end outcomes for children who wear hearing Joanne DeLuzio with senior citizens and their unique aids, and it’s pretty obvious from the title, and I began co- communication requirements. what that article is about. Alberto Behar, ordinating this who recently received a major award one-day conference Also found in this issue of the Canadian from the Canadian Standards Association back in 1986 and Hearing Report is a transcript from the (see last issue of the Canadian Hearing we just had our final one earlier this panel/discussion section of the fourth Report) has co-written an article with one spring – the 28th Annual Seminars on Seminars on Audition between Harry of the graduate students at Ryerson Audition. The purpose of this seminar Levitt and Edgar Villchur who were the University in Toronto and examine was to get clinicians, hearing aid design speakers for that meeting. Harry Levitt whether headsets with a dual function of engineers, and researchers together in is a retired professor from CUNY in New hearing protection and electronic one room and provide a speaker or York and is well known for his communication can be damaging to one’s speakers that will set the milieu for pioneering work on digital hearing aids. hearing. discussion. In many ways, much of what Edgar Villchur invented multi-band was learned was during coffee breaks compression and is the father of the air And of course we have our regular and from the person sitting next to you. suspended loudspeaker. Previous issues columnists, Calvin Staples (From the Although there are a number of other of the Canadian Hearing Report have had Blogs), Gael Hannan (The Happy HoH), continuing education opportunities now Founders of Our Profession interviews and Dr. Vincent Lin from the such as on-line CEUs, there was with both of these pioneers. Sunnybrook Health Sciences Centre and something special about a face-to-face his colleagues have contributed under meeting with people who may not At the 2012 Canadian Academy of the banner of the E in ENT column Oral normally cross your paths. All proceeds Audiology convention in Ottawa I vs. transtympanic injection of steroids as went to scholarships either at the attended a wonderfully clear and treatment options for sudden sensori- University of Western Ontario (Seminars thoughtful presentation by Andre neural hearing loss. on Audition scholarship) or the Institute Marcoux (who was the first editor of the of Biomaterials and Biomedical Canadian Hearing Report). He spoke To round things out Dr. Brian Fligor Engineering at the University of Toronto about some new technologies and new from Boston has agreed to write this (Poul B. Madsen Scholarship). The approaches in ABR measurements. I issue’s Clinical Questions column, but Seminars on Audition scholarship thought it was so clear that even I could you will have to read further to see what allowed a student in their final year of understand it, so he was asked to write he said. their master’s degree to attend an “extra- something for us. ordinary” facility anywhere in North I wish you all a pleasant warm season, America. Recipients over the years have And talk about clarity, Dr. Jim Jerger wear a hat, use sunscreen, and don’t gone to the Canadian arctic to see how wrote a wonderful article for the forget to register for the next annual hearing aid evaluations and follow-up International Journal of Audiology (IJA) conference of the Canadian Academy of was performed over a 3000 km distance called “Why the audiogram is upside- Audiology this October in by dog sled, and also to world class down.” I saw it in draft form and Newfoundland and Labrador. pediatric facilities such as Boys Town in immediately called him up (and Ross Nebraska. Roesser, the editor of the IJA) to get Marshall Chasin, AuD, M.Sc., Aud(C), permission to reprint it. They graciously Reg. CASLPO, Editor-in-Chief This issue of the Canadian Hearing agreed but I was second in line. The [email protected] Report has a selection of three Hearing Review was before me and so Canadian Hearing Report 2013;8(3):3. summaries of the some speakers from you may have seen this before, however, this last Seminars on Audition entitled it certainly is well worth the read and “Hearing Though the Ages” with the triple exposure.
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 3 Love at first visit
It can happen with Flex:trial Help more patients experience the amplification they need at their very first visit. Introducing the only solution that lets you program one set of hearing instruments to different technology levels so you can offer an immediate test run of the exact hearing instrument they need. Make them love you even more with Flex:trial.™ Call 1-800-265-8255 unitron.ca Vol.8 No 3 | 2013 contents Revue canadienne d’audition DEPARTMENTS FEATURES 3 Message from the Editor-in-Chief RESEARCH AND DEVELOPMENT ______7 Message du L’editeur en chef FOCUS Vol. 8 No 3 • 2013 28 Headsets – Are They Damaging Your 9 Clinical Questions Hearing? Official publication of the WITH BRIAN J. FLIGOR, SCD BY ALBERTO BEHAR, PENG, CIH AND Canadian Academy of Audiology GABE NESPOLI, BSC, MA 14 By Popular Demand! 31 Why the Audiogram Is Upside-Down 41 Third Party Funding: Frequently Asked BY JAMES JERGER, PHD Questions BY CARRI JOHNSON, AUD Publication officielle de l’académie canadienne d’audiologie FEATURES www.canadianaudiology.ca ARTICLES FROM THE FINAL
E DITOR- IN-C HIEF /É DITEUR EN CHEF COLUMNS SEMINARS ON AUDITION Seminars on Audition Review Marshall Chasin, AuD., MSc, Reg. CASLPO, 10 FROM THE BLOGS@ 36 Director of Research, Musicians’ Clinics of Canada HEARINGHEALTHMATTERS.ORG BY MARSHALL CHASIN, EDITOR-IN-CHIEF BY CALVIN STAPLES, MSC A S SOCIATE E DI TORS /ÉDITEU RS ADJOINTS 37 Early Intervention for Children with Steve Aiken, PhD, Dalhousie University 13 THE HAPPY HOH Hearing Loss: An Update for 2013 Alberto Behar, PEng, Ryerson University Hearing Loss – A Family Affair BY SUSAN SCOLLIE Leonard Cornelisse, MSc, Unitron Hearing BY GAEL HANNAN Joanne DeLuzio, PhD, University of Toronto 40 My Horsie Has a Cochlear Lendra Friesen, PhD, Sunnybrook Health Sciences Centre 15 The “E” in ENT Implant: The Importance of Child-Centred Gael Hannan, Hearing Loss Advocate Oral vs. Transtympanic Injection of Outcomes for Children with Hearing Loss Bill Hodgetts, PhD, University of Alberta Steroids as Treatment Options for BY JOANNE DELUZIO, PHD Lorienne Jenstad, PhD, University of British Columbia Idiopathic Sudden Sensorineural Hearing André Marcoux, PhD, University of Ottawa Loss Sheila Moodie, PhD, University of Western Ontario BY MARY EDGAR, BKin, DAVID CLINKARD, MS, AND 42 When the Brain Gets Hard of Hearing: Calvin Staples, MSc, Conestoga College VINCENT LIN, MD, FRCSC Paying Attention to Cognition in Kim L. Tillery, PhD, State University of New York, at Fredonia Hearing Rehabilitation Rich Tyler, PhD, University of Iowa BY MARILYN REED, MSC Michael Valente, PhD, Washington University FEATURES RESEARCH AND DEVELOPMENT PANEL DISCUSSION FROM THE 4TH M ANAGING E D ITOR /DIRECT EUR DE LA R É DACTION SEMINARS ON AUDITION Scott Bryant, [email protected] FOCUS 19 Noise Reduction to Achieve Quality ABR 46 Signal Processing Techniques in Hearing C ONTRIBU TORS Measurement Aids Fourth Annual Seminars on Audition Marlene Bagatto, Doreen Bartlett, Alberto Behar, Christine Brown, BY ANDRÉ MARCOUX, PHD AND February 25, 1989 (Toronto) Marshall Chasin, Debbie Clench,David Clinkard, Joanne DeLuzio, ISAAC KURTZ, MHSC, PENG Mary Edgar, Brian Fligor, Gael Hannan, James Jerger, Isaac Kurtz, Vincent Lin, April Malandrino, Andre Marcoux, Sheila Moodie, Gabe Nespoli, Marilyn Reed, Frances Richert, Susan Scollie, Richard Seewald, Calvin Staples 24 Audiological Outcomes for Children Who Wear Hearing Aids A RT D IRECTOR/DESIGN /DIRE CTEUR ARTISTIQUE /DESIGN BY MARLENE BAGATTO, SHEILA MOODIE, Follow us on Twitter @chr_infor Andrea Brierley, [email protected] CHRISTINE BROWN, APRIL MALANDRINO,
SALES AND CIRCULATION COORDINATOR./ FRANCES RICHERT, DEBBIE CLENCH, COORDONATRICE DES VENTES ET DE LA DIFFUSION DOREEN BARTLETT, RICHARD SEEWALD, AND Brenda Robinson, [email protected] SUSAN SCOLLIE
ACCOUNT ING /COMPTAB ILITÉ Susan McClung
G ROUP P UBLISHER /CHEF DE LA DIRE CTION John D. Birkby, [email protected] ______Canadian Hearing Report is published six times annually by Andrew John Publishing Inc. with offices at 115 King Street West, Dundas, On, Canada L9H 1V1. We welcome editorial submissions but cannot assume responsibility or commitment for unsolicited material. Any editorial material, including pho- tographs that are accepted from an unsolicited contributor, will become the property of Andrew John Publishing Inc. FEEDBACK We welcome your views and comments.Please send them to Andrew John Publishing Inc., 115 King Street West, Dundas, ON, Canada L9H 1V1. Copyright 2013 by Andrew John Publishing Inc. All rights reserved. Reprinting in part or in whole is forbidden without express written con- sent from the publisher. Publications Agreement Number 40025049 • ISSN 1718 1860 INDIVIDUAL COPIES Return undeliverable Canadian Addresses to: Andrew John Publishing Inc. 115 King Street West, Individual copies may be purchased for a price of $19.95 Canadian. Bulk Dundas, ON, Canada L9H 1V1 orders may be purchased at a discounted price with a minimum order of 25 copies. Please contact Ms. Brenda Robinson at (905) 628-4309 or [email protected] for more information and specific pricing. REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 5 Amigo Star brings out the stars in class
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Amigo Star is a stylish, discreet, comfortable and easy Out of the box, Amigo Star is easy to # t and easy to use ear level FM receiver. Field trials completed in to program without the use of computers or the Fall of 2012 suggested that student’s with auditory program software. Compatible with all Amigo FM processing di! culties, unilateral hearing loss and minimal transmitters and other transmitters on the 216 hearing loss preferred the Amigo Star to their previous MHz band, it easily integrates into classrooms ear level FM receiver. They stated that comfort, a useable using sound # eld or other personal FM. volume control, and the discreet thin tube as unique, In moments, students will be e$ ortlessly hearing important features they liked in their Amigo Star device! the teacher, while still having access to their Amigo Star is dust and water resistant and is very durable. fellow student’s comments in the classroom. It is available in six colors and a selection of stickers that Amigo Star, is the new star in school! allows students the option to customize.
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Message du L’editeur en Chef |
endant 28 ans, les Marilyn Reed. Comme vous devez Marlene Begatto et ses collègues à Pséminaires en ouïe certainement le deviner par le domaine l’Université Western (le nouveau nom de ont été parmi mes de spécialité des conférencières, le the University of Western Ontario) a passe-temps favoris. séminaire a commencé avec des jeunes rédigé un article enchanteur sur les Joanne DeLuzio et enfants et a fini avec des personnes du résultats audiologiques pour les enfants moi-même avons troisième âge et leurs exigences uniques qui portent des appareils auditifs, et commencé à coordon- en communications. évidemment le titre est explicite. Alberto ner cette conférence Behar, qui a récemment reçu un prix d’une journée en On trouvera aussi dans ce numéro de la majeur de l’association canadienne de 1986 et nous venons Revue Canadienne d’audition, une normalisation (voyez le dernier numéro d’avoir notre toute dernière plutôt ce transcription de la section du panel de de la Revue Canadienne d’audition) a printemps – le 28ieme séminaire annuel discussion du quatrième séminaire en coécrit un article avec un des étudiants en ouïe. L’objectif de ce séminaire était ouïe entre Harry Levitt et Edgar Villchur diplômés de l’Université Ryerson de de réunir ensemble dans une même salle qui étaient les conférenciers à cette Toronto et y examine les écouteurs cliniciens, ingénieurs concepteurs des réunion. Harry Levitt est professeur à la double fonction de protection de l’ouïe appareils auditifs, et chercheurs et de retraite du CUNY à New York et bien et de communication électronique et proposer un conférencier ou des con- célèbre pour son travail pionnier sur les s’ils sont nuisibles pour l’ouïe. férenciers qui établira le milieu de la dis- appareils auditifs numériques. Edgar cussion. A bien des égards, l’apprentis- Villchur a inventé la compression multi Bien entendu, nous avons nos sage se passait durant les pauses cafés et bande et est le père du haut-parleur à air chroniqueurs réguliers, Calvin Staples de la personne assise à côté. Même main- suspendu. Des numéros antécédents de (From the blogs), Gael Hannan (The tenant, avec des opportunités de forma- la Revue Canadienne d’audition ont Happy HoH), et Dr. Vincent Lin du tion continue comme les CEU en ligne, affiché des entrevues avec ces deux centre des sciences de santé de c’est tout à fait spécial que de rencontrer pionniers dans la rubrique Les Sunnybrook et ses collègues qui ont des gens face à face, des gens qui peut- fondateurs de Notre Profession. contribué sous la bannière de la être vous n’auriez pas rencontré chronique the E in ENT, au sujet des autrement. Toutes les recettes ont été Au congrès de l’académie canadienne injections de stéroïdes par voir orale versées sous forme de bourses soit à the d’audiologie à Ottawa de 2012, J’ai assisté versus tympanique comme options de University of Western Ontario (Bourse à une présentation admirablement claire traitement pour la perte auditive des séminaires en ouïe) ou à the Institute et réfléchie par André Marcoux (qui était neurosensorielle soudaine. of Biomaterials and Biomedical Engi- le premier rédacteur en chef de la Revue neering de l’Université de Toronto (La Canadienne d’audition). Il a évoqué Pour fermer la boucle, Dr Briam Fligor bourse de Poul B. Madsen). Les bourses certaines technologies et approches de Boston a bien voulu rédiger la des séminaires en ouïe ont permis à une nouvelles dans les mesures des réponses chronique Questions Cliniques de ce ou un étudiant en dernière année de évoquées auditives du tronc cérébral. J’ai numéro, mais il faudra lire plus en avant maitrise de fréquenter un établissement pensé que c’était tellement clair que même pour en savoir plus. “extraordinaire” n’importe où en moi je pouvais comprendre, alors il a été Amérique du nord. Sur plusieurs années, sommé de nous écrire quelque chose. Je vous souhaite à toutes et à tous une les récipiendaires sont allés dans l’arc- belle saison chaude, utilisez l’écran tique canadien pour voir comment les En parlant de clarté, Dr Jim Jerger a solaire, portez un chapeau, et n’oubliez évaluations des appareils auditifs et les rédigé un merveilleux article pour the pas de vous inscrire à la prochaine suivis sont exécutés sur 3000km de dis- International Journal of Audiology (IJA) conférence annuelle de l’Académie tance à l’aide de traineaux à chiens, et intitulé “Pourquoi l’audiogramme est Canadienne d’Audiologie qui aura lieu aussi dans des établissements de pédia- inversé.” Je l’ai vu sous forme d’ébauche le mois d’octobre prochain à Terre trie de renommée internationale tel que d’article et je l’ai immédiatement appelé Neuve et Labrador. le Boys Town dans le Nebraska. (et Ross Roesser, le rédacteur en chef de IJA) pour demander la permission de le Marshall Chasin, AuD, M.Sc., Aud(C), Ce numéro de la Revue Canadienne réimprimer. Ils ont bien voulu mais j’étais Reg. CASLPO d’audition affiche une sélection de trois le deuxième sur la liste. The Hearing Éditeur en chef résumés de certains conférenciers au Review était avant moi alors vous l’auriez [email protected] dernier séminaire en ouïe intitulé “ l’ouïe peut-être déjà vu avant, mais Canadian Hearing Report 2013;8(3):7. à travers les âges” avec des contributions certainement, il vaut bien la peine d’être de Dr. Susan Scollie, Dr. Jo DeLuzio, et relu et trois fois.
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 7
CLiniCaL Questions |
Ear” (TFOE) and others (especially With Brian J. Fligor, ScD Board Certified in audiologists) use “Real Ear Unaided Audiology with a Specialty Certification in Gain” (REUG). For the purposes of this Pediatric Audiology, Director of Diagnostic question, the two acronyms are Audiology, Boston Children's Hospital; Instructor equivalent. in Otology and Laryngology, Harvard Medical School. For broadband noise, the TFOE essentially gives about 7 dB higher level at the eardrum/ear canal than you get at the shoulder/diffuse field. This means a Q: We are trying to relate sound forgotten that the DRC were developed DRC that is 85-dBA for 8-hr TWA with pressure levels (SPL) in the ear canal with microphones in the diffuse field, 3 dB exchange rate would be 92-dBA to damage risk criteria for hearing and not in a coupler (e.g., a 2 cc for 8-hr TWA with 3 dB exchange rate loss ... it seems most of the standards coupler, or in an ear canal – which is of if the location of measurement was the use dBA not dB SPL. Are there any course also a coupler). Coupler-to- ear canal rather than diffuse field. A standards based on SPL in humans or diffuse-field transfer functions are even “correction factor” can then be of a way to convert SPL to dBA? more variable than dB SPL (flat) to A- subtracted from the ear canal (probe weighted dB SPL – unless all your tube microphone) measure to change A: The SPL in the ear canal versus energy is above 1000 Hz where there the results to equivalent diffuse field Damage Risk Criteria (DRC) came up are minimal SPL-dBA differences. results for a valid estimation of DRC. immediately in the early 2000s when I The real ear to diffuse correction factor was doing my dissertation on One of the problems in this area is can be used but only if the exact nature headphones and risk for hearing loss. terminology. Some researchers use the of the spectrum is known. Several authors before and since have phrase “Transfer Function of the Open Canadian Hearing Report 2013;8(3):9.
CANADIAN ACADEMY OF AUDIOLOGY PO Box 62117 777 Guelph Line, Burlington ON, L7R 4K2 T: 905-633-7114/1-800-264-5106 F: 905-633-9113 E: [email protected] BOARDOFDIRECTORS / CONSEIL DE DIRECTION
Steve Aiken Rex Banks Salima Jiwani Maxine Armstrong President/Présidente Director/Directeur Director/Directeur Director/Directeur Dalhousie University Canadian Hearing Society University of Toronto Toronto General Hospital Halifax, NS Toronto, ON Toronto, ON Toronto, ON Susan Nelson-Oxford MJ Desousa Gurjit singh President-Elect /Présidente-Désignée Director/Directeur Director/Directeur Vancouver Island Health Authority Connect Hearing University of Toronto Victoria, BC Toronto, ON Toronto, ON
Victoria Lee Susan English-Thompson Glynnis Tidball Past President/Présidente-Sortant Director/Directeur Director/Directeur Auditory Outreach Provincial Sackville Hearing Centre St. Paul’s Hospital Program Burnaby, BC Sackville, NS Vancouver, BC
Petra Smith Joy Gauvreau Erica Wong Treasurer/Trésorière Director/Directeur Director/Directeur Hastings Hearing Centres Costco Mount Sinai Hospital Steinbach, MB Saskatoon, SK Toronto, ON
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 9 | froM the [email protected]
In a May 1 news release, John Sullivan of slices. It then deposits layers of materials the Office of Engineering Communication to build up a finished product. at Princeton reported that the primary purpose of the researchers was to develop One example of this approach is an effective means of merging electronics CAMISHA (computer-aided-manu- with biological tissue. The scientists used facturing-for-individual-shells-for-hearing 3-D printing of cells and nanoparticles -aids), which was invented by Soren followed by cell culture to combine a Westermann at Widex, and is now used small coil antenna with cartilage, creating to build 95% of custom hearing aids. By Calvin Staples, MSc what they termed a bionic ear. Hearing Instrument Specialist According to Princeton, the bionic ear Faculty/Coordinator, Conestoga College The lead researcher is Michael McAlpine, project marked the first time that [email protected] an assistant professor of mechanical and researchers have demonstrated that 3-D aerospace engineering at Princeton. He printing is a convenient strategy to s April showers have brought May told Sullivan, “There are mechanical and interweave tissue with electronics. The Asnow in most of Ontario and thermal challenges with interfacing researchers used an ordinary 3D printer throughout many parts of Canada, most electronic materials with biological to combine a matrix of hydrogel and calf of us have just finished up spring materials. However, our work suggests a cells with silver nanoparticles that form conference season. Conferences often new approach – to build and grow the an antenna. The calf cells later develop provide clinicians the opportunity to biology up with the electronics into cartilage. view the latest and greatest products synergistically and in a 3-D interwoven from hearing aid manufacturers. The format.” The initial device developed by McAlpine blogs in this series will focus on the new and colleagues detects radio waves, but developments in the hearing and The Princeton team has been doing the team plans to incorporate other hearing aid industry. I frequently visit research in cybernetics for several years. materials that would enable it to hear the blogs at hearinghealthmatters.org as This promising field seeks to design acoustic sounds. While it will take much a springboard to further topic bionic organs and devices to enhance more work to develop a bionic ear that investigation, I hope our readers find human abilities. The bionic ear project could restore or enhance human hearing, the topics below insightful and useful was the first effort by McAlpine and McAlpine said that in principle it should clinically. As you will see from the colleagues to create a fully functional be possible to do so. submissions below, numerous organ: one that replicates a human ability achievements have occurred that will and then uses embedded electronics to The team that developed the bionic ear help shape our industry into the future. extend it. consists of six Princeton faculty members, Happy Reading! two graduate students from Princeton Writing in the journal Nano Letters, the and Johns Hopkins University, and Ziwen scientists said that cybernetics, “has the Jiang, a high school student at the Peddie potential to generate customized School in Hightstown, NJ. McAlpine said replacement parts for the human body, or of the precocious teenager, “We would even create organs containing capabilities not have been able to complete this By David Kirkwood beyond what human biology ordinarily project without him, particularly in his provides.” skill at mastering CAD designs of the Blending electronics and biology, bionic ears.” scientists at Princeton University have In order to replicate complex three- used readily available 3-D printing tools dimensional biological structures, the http://hearinghealthmatters.org/hearing to create a functioning “bionic ear” that researchers turned to 3-D printing. A 3- newswatch/2013/scientists-develop-a- can detect radio frequencies far beyond D printer uses computer-assisted design bionic-ear-with-super-human-power/ the range of normal human capability. to conceive of objects as arrays of thin
10 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION |
checks. The monkeys encourage making of the Ida Institute, said, “The Ideas hearing checks part of a health routine Campaign sparked the creativity and that also includes getting one’s eyes and passion of people around the world.” By David Kirkwood teeth checked on a regular basis. The three monkeys image can be used in ideas Worth hearing ANAHEIM, CA–An international public many media, including print and The prize-winning ideas were selected art initiative, a “Three Wise Monkeys” broadcast advertising, web sites, by a panel of judges including Brenda campaign to encourage regular hearing billboards, bus posters, and cinema Battat, executive director of the Hearing health checks, and a pocket-sized trailers. Loss Association of America; Tom Healy, electronic hearing testing device a writer, poet and chairman of the captured top honors in the Ida Institute’s Khalid Islam of Bangladesh invented the Fulbright Foreign Scholarship Board; competition, Ideas, Speak up – Action and winning idea in the Best Event category. Bob Isherwood, former worldwide Awareness for Hearing Loss. The winning He devised “Look Who’s Hearing,” an creative director of Saatchi & Saatchi, entries were celebrated at a reception international public art initiative that the Ideas Agency; Sergei Kochkin, PhD, held here April 3 at the start of the would involve “fitting” hearing aids on former executive director of the Better American Academy of Audiology’s statues in major cities around the world. Hearing Institute; and Helle Østergaard, annual convention, AudiologyNOW! The artist-designed hearing aids could executive director of the Crown Princess 2013. be mounted as sculptures and then Mary Foundation. auctioned off to support hearing health The purpose of the international contest charities. An Internet campaign would These and some of the other best ideas was to stimulate ideas with the potential enable people to follow this initiative, submitted can be viewed online at Ideas to create public awareness of hearing track the next statue, and spread Worth Hearing. The Ideas Catalog is loss, put hearing loss on the public awareness. designed to inspire and to help people agenda, and encourage people to take around the world take action and start action to address hearing loss. In the Best Gadget category, Kasper raising awareness of hearing loss in their Rubin, a Dane, won the blue ribbon for communities. The Ida Institute, a Danish-based his Hearing Tone Test Card, an independent non-profit foundation inexpensive electronic card that would http://hearinghealthmatters.org/hearin funded by the Oticon Foundation, serve as a practical hearing checker. The gnewswatch/2013/three-best-ideas-to- launched the ideas competition at pocket-sized card uses simple electronic raise-awareness-of-hearing-loss-are-ho AudiologyNOW! 2012 held in Boston. technology like that used in singing nored-at-aaa-convention/ Over the following months it generated greeting cards. However, instead of more than 400 submissions from all making music, the technology is used to over the world. test hearing. By Robert Traynor three top priZes At the reception in Anaheim where the From these, first prizes were awarded in contest winners were announced, Niels Most audiologists realize that noise- three categories. The winning entry in Boserup, chairman of the Oticon induced hearing loss (NIHL) refers to a the Public Awareness Campaign Foundation, said, “We recognize that to gradual, cumulative and preventable category was submitted by Curtis Alcott, continue the good work of this project decline in auditory function that follows from the United Kingdom. Entitled and to achieve increased public repeated exposure to loud noise. It is, of “Three Monkeys: Eyes Checked. Teeth awareness of hearing loss worldwide will course, the leading cause of preventable Checked. Hearing Checked,” his idea require a strategic, dedicated initiative.” hearing loss. It is also estimated that was to link a simple message to the He added that the Oticon Foundation 10% (30 million) of Americans are iconic three wise monkeys (“See no evil, “will investigate ways to develop and encountering hazardous levels of noise, hear no evil, speak no evil”) to raise implement the worthy ideas.” that 25% of those working in the awareness of regular hearing health Lise Lotte Bundesen, managing director construction, mining, agriculture,
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 11 | manufacturing, transportation, and Rick Nelson said, “Sang them all the old loss and the pre-clinical research that military industries routinely encounter songs, thought that is why they came” contributed to the development of noise levels above 90 dB (A), and that and that IS why they came…and a super AuraQuell. During clinical studies, such noise exposure has already time was had by all! The Next Day: You guinea pigs who had been administered generated a sizeable population of wake up with horrible tinnitus, AuraQuell experienced about eighty workers who meet the Occupational probably a hangover as well and wonder percent preventative blockage of noise- Safety and Health Administration’s why it was so important to get close to induced hearing impairment (“The (OSHA) definition for material the speakers during the rock concert the treatment one hour before a five hour impairment of hearing” (over 25 dB night before. As the day goes on you exposure to 120 decibel (dB) sound threshold at 1000, 2000, and 3000 Hz). begin to feel better, but the tinnitus pressure level noise, and continued once This number is probably much greater lingers on reminding you of a major daily for five days.” Josef M. Lynn, Ph. among workers and participants in high noise exposure the night before. Over D., the Lynn and Ruth Townsend noise activities in countries where the next day or so, the tinnitus will Professor of Communication Disorders, regulations are not as stringent as those usually subside and we end up OK, but Director of the Center for Hearing in developed countries. Since workers as audiologists we know that there has Disorders at the University of Michigan and those with recreational hearing been some hair cell destruction.Typically, Department of Otolaryngology’s Kresge losses can have significant effects on their the noise exposure causes levels of toxic Hearing Research Institute and co-leader employment, social interactions, family chemicals called “free radicals” inside the of the research expects AuraQuell could interactions, protecting hearing health in hair cell to rise beyond manageable effectively block 50% of noise induced the workplace and while having fun has levels, and the cell dies. We also know hearing loss in humans. A trademark for become very important. Programs and that if we continue to attend too many AuraQuell was granted in June 2009. regulations for occupational exposure of these concerts the exposure to the Clinical human testing of AuraQuell is (e.g. maximum allowed daily noise intense sound levels will ultimately lead being evaluated in four multinational doses) have been designed, but no matter to a number of hair cell deaths and, trials: “Military trials in Sweden and where you live there are virtually no subsequently, a permanent hearing Spain, an industrial trial in Spain, and standards for recreational noise, an impairment. BUT….What if we could trial involving students at the University emerging contributor to noise-induced reverse the process, make it like we had of Florida who listen to music at high hearing loss. There are numerous sources never been exposed at all….a Morning volumes on their iPods and other PDAs.” of non-occupational noise exposure. After Pill…..Now it probably will not The human clinical trials for AuraQuell Clark and Bohne have compiled a partial do too much for the hangover, but there maybe in the form of a tablet or snack list of significant sources of leisure noise, may be a method to minimized or bar. These trials studies are funded by and music figures prominently in their eliminate the effects of the noise National Institute of Health (NIH).”This construct. exposure due to taking a pill that is the first NIH – funded clinical trial actually works. involving the prevention of noise- Music, in addition, transcends the induced hearing loss.” AuraQuell may recreational setting to pose an the Morning after prove to limit induced hearing loss of occupational risk of NIHL for groups Studies in this area have been ongoing military personal exposed to improvised such as music venue workers and music for a number of years. Based upon their explosive devices (IEDs) and other performers, even the audiences…… studies, researchers at the University of noises. It appears that AuraQuell is still Michigan, Kresge Hearing Research in clinical field trials, but if these trials think BaCk Institute have developed AuraQuell are successful, Dr. Joseph Miller, the Most of us (yes, even audiologists) have (pill) which is a combination of Vitamins noise-induced hearing loss prevention “been there” at one time or another. You A, C and E, plus magnesium, taken concoction could be available within are a fan! A BIG FAN LL Cool J, before a person is exposed to loud two years. Beyonce, Madonna, maybe even the noises. The funding for the Michigan Stones and your favorite musical artist is project was provided by General Motors http://hearinghealthmatters.org/heari in town for a greatest hits concert! You and the United Auto Workers that led nginternational/2013/the-morning- have a babysitter, a designated driver. to the 2007 study of the after-pil/ Look out, you are out on the town! As mechanism attributed to induce hearing Canadian Hearing Report 2012;8(3):10-12.
12 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION the happY hoh |
Hearing loss – A Family Affair By Gael Hannan [email protected] o – hearing care scenario of rising irritation and heated the future. Yprofessionals! Can words. anybody tell us where a The other change involves his parents. family can sign up for a Me: Why did you do that? Up until now, Mommy has been the only communication course? Him: (sigh) Do what? one playing in the hearing loss sandbox. (And I’m not talking Me: You started talking to me as you But now Daddy, who has been sitting on about a mandatory walked away. You KNOW I can’t the fence between the two worlds of program involving a understand when you do that. hearing (his) and hearing loss (mine), psychologist or the Him: Sorry, hon, I forgot. may have stuck a toe in the sandbox, too. police.) It’s tough enough for a hard of Me: You forgot, you forgot! How many When it’s noisy, he doesn’t hear me as hearing person to find access to effective times will it take before you well as he used to. Recently, at a hearing aural rehabilitation, let alone a program remember? health fair I was involved with, my that includes communication partners Him: Until death do us part, OK? I will husband signed up for free hearing test. like spouses and children past the spit- always forget sometimes, I can’t help Although the testing environment was up stage. it. Now, do you wanna know what I less than ideal, his hearing was “normal” said, or not? until 4000 Hz – and then kaboom, the The need is great. In many families, famous NIHL notch! hearing loss is the elephant in the room, Hearing loss is a family affair. Its impact the monkey wrench thrown into family reaches beyond the personal to anyone The day may have arrived that the former communication. Attending even a single within communicating distance. In my Hearing Husband and I must practice facilitated session on communication house, even after living together for years, two-way communication strategies. I now strategies can make a big difference in the simply mis-communications can still need to practice what I preach, making quality of family life. I know what you spark reactions that range from a laugh to sure, for example, that he can see my face might be thinking – and to keep this mild irritation to full-on frustration. This in order to understand what I’m saying. animal analogy going – you can lead a is part of our more-or-less accepted family horse to water but you can’t make it dynamic and, when the bad moment But my husband and I have grown into drink. People may not break down your passes, we move on – time after time. this situation – I was already hard of door to sign up for the session or course, hearing when we got married. What but the ones that do will benefit greatly. But the family affair has recently become about the couples or families who more complicated. One change involves experience hearing loss after years of It can be a bit lonely as the only HoH in the 17 year-old son who has already being together? The emotional impact is the house. Just because a family is well- moved beyond our sphere of influence. often immeasurable. Internet resources versed in effective communication The little boy who was raised to respect such as personal blogs and consumer/ strategies, doesn’t mean it actually the gift of hearing and understand the professional hearing loss sites offer a great practices them. This is not because of consequences of hearing damage, now deal of helpful information, but don’t pettiness, negligence or a lack of caring, enjoys his music at dangerous levels. match the effectiveness of learning but simply because family members, in There’s not much I can do beyond and practicing good communication the moment, can forget the basics of good offering a good supply of earplugs (which strategies with real people. communication. A turned-away face or a I can no longer stuff in his ears for him) question bellowed from upstairs can suck and reminding (nagging) him that if he As hearing care professionals, you can the pleasant air out of a room in two continues to abuse his hearing, we’ll be help ensure your clients’ success by seconds flat, kick-starting a familiar comparing hearing aids at some point in helping their families deal with the
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 13 | emotional barriers of hearing loss, professional in my area cares to offer one, Be sure to visit Gael’s blog, “The Better clearing the way to better commun- I’ll sign up me and my boys. A good Hearing Consumer” at: ication with real-life strategies that work. family dynamic is dependent on many http://hearinghealthmatters.org/. things, and handling hearing loss is Canadian Hearing Report 2012;8(3):13-14. The time is ripe to introduce family definitely one of them. communication sessions. If a hearing By Popular Demand! Outstanding CAA Pre-conference Workshops October 16, 2013 pre-ConferenCe a: vestiBuLar Mounting research points to the people that bridges age-related declines evaLuation and connection between hearing loss and in hearing and cognition. rehaBiLitation: aLL the BasiCs dementia; however, the mechanisms You need to knoW underlying the connection remain Part 1 Research evidence of the Take a tour of the vestibular system; learn unknown. Possible connections will be connection between hearing and about available vestibular tests and how described. Recently published diagnostic cognitive decline in aging to recognize vestibular disorders. Reha- guidelines regarding mild cognitive Ulrike Lemke – Scientist Phonak AG bilitation techniques will be introduced impairment (MCI) and dementia will be Switzerland – Diagnostic continuum from and you will have the opportunity to “ask reviewed. The need to include hearing healthy aging to dementia the experts” who deliver services in an testing in protocols for screening and Dr. Frank Lin – Johns Hopkins University active hospital-based centre. This work- assessing MCI and dementia will be – Epidemiological evidence of the shop will appeal to audiologists with discussed. Ongoing research on the connection of hearing loss and cognitive novice and experienced knowledge levels possible advantages of including decline in aging in vestibular function. cognitive measures in audiology Dr. Kathy Pichora Fuller – University of protocols will be presented. Importantly, Toronto – Experimental research evidence Maxine Armstrong provides vestibular there is great interest in finding ways to of the link between hearing loss and training to medical students, otolaryngol- stave off or slow down the onset of cognitive decline in aging ogy residents, neurotology fellows, audi- dementia. Whether hearing loss ology students, and SLP students. She prevention and/or hearing rehabilitation Part 2 Determining what older adults manages the Toronto General Hospital’s could reduce the risk of dementia is an with hearing loss and cognitive decline Centre for Advanced Hearing and important question for researchers and want and need Balance Testing and The Munk Hearing clinicians. The issues to be covered will Mary Oberg – Audiologist Sweden – Centre. Carolyn Falls assists Maxine in consider questions such as: Can Views of 80 year olds about hearing aid overseeing the centres and both partici- individuals with dementia benefit from and rehabilitation options. pate in University of Toronto based hearing aids and/or other forms of Marilyn Reed – Baycrest – Rehabilitative research activities. audiologic rehabilitation? How could options for older adults with hearing loss audiologists offer help to caregivers for and dementia pre-ConferenCe B: hearing individuals with dual hearing and Kate Dupuis – University of Toronto – and Cognitive deCLine in cognitive impairments? The workshop Screening for cognitive loss by aging: neW direCtions for will include some hands-on exercises, audiologists and screening for hearing audioLogiCaL praCtiCe interactive discussions and presentations loss by psychologists We have assembled a world-class team of by international researchers as well as researchers and clinicians to bring you up clinical experts in otolaryngology, Conference details: to the minute evidence based knowledge audiology and psychology who are trying www.canadianaudiology.ca/conference2013 and how to apply it clinically. to develop new approaches to care for
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Oral vs. Transtympanic Injection of Steroids as Treatment Options for Idiopathic Sudden Sensorineural Hearing loss
By Mary Edgar, BKin, David Clinkard, MS, and Vincent lin, MD, FRCSC [email protected]
About the Authors Mary Edgar (left) has a bachelor’s degree in kinesiology and has just been accepted into the MSc physiotherapy program at UBC. She has worked as an audiometric technician at the Vernon Health Unit for the past five years. David Clinkard (middle), and Vincent Lin (left) are with the Otolaryngology Department at Sunnybrook Health Sciences Centre, Toronto, Ontario.
aBstraCt There is a myriad of treatment options for sudden sensorineural hearing loss. However clinical evidence supporting the efficacy of these treatments are generally limited to case series and a few clinical trials. Due to the paucity of good clinical evidence, the treatment of sudden sensorineural hearing loss continues to challenging for otolaryngologists. Although controversial, corticosteroids are considered the standard of care. A typical treatment regiment is a tapering course of high dose oral corticosteroids. Recently, transtympanic corticosteroids have been administered as salvage therapy, primary therapy or in addition to oral corticosteroid treatments. The role of oral versus transtympanic corticosteroid therapy remains poorly understood.
udden sensorineural hearing loss Given the high spontaneous recovery the most common presenting symptoms S(SSNHL) is a relatively common rates (32–65%), the actual incidence of of SSNHL and may be mistaken for less complaint in audiology and otolaryn- ISSNHL may be higher.3 ISSNHL serious conditions such as cerumen gology practices. SSNHL is the acute typically occurs between the ages of 50 impaction or nasal congestion leading to onset of hearing loss of at least 30 dB in and 60, with no gender predominance.4,5 eustachian tube dysfunction7. These can at least three different frequencies over a Etiology is often unknown, with the be ruled out with a complete history, 72-hour period.1 While usually majority (85%) of patients having no physical exam, and audiologic unilateral in origin, bilateral occurance identifiable cause.5,6 However, viral, evaluation.2 A rapid diagnosis of SSNHL is possible, though rare (1–2%). vascular and immunologic contributions is vital because a delay in diagnosis may have been suggested as possible reduce the efficacy of treatments thought The overall incidence of diagnosed etiologies.2,3 to restore hearing.3,4 ISSNHL ranges from 5 to 20 per 100,000 persons per year, with some diagnosis and treatMent Given the multifactorial and ultimately estimates as high as 160 per 100,000.2 Aural fullness and muffled hearing are unknown nature of ISSNHL multiple
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 15 | therapy options have been proposed. universally correlated with decreased indicated. If the hearing loss is unilateral, These include steroids, vasodilators, rates of hearing recovery and lower magnetic resonance imaging (MRI) is anticoagulants, plasma expanders, absolute threshold gains.5 The greatest ordered to rule out retrocochlear causes vitamins, and hypobaric oxygen.3,5,8 spontaneous improvement in hearing such as an acoustic schwannoma. If occurs during the first two weeks and these investigations fail to a reveal cause Current standard of care is a tapering late recovery has been reported but is of hearing loss, then prednisone at dose of systemic steroids, either oral or rare. Treatment with corticosteroids 1 mg/kg/day for the first six days and intravenous. The treatment should be appears to offer the greatest recovery in then tapering for eight days, for a 14-day started as soon after diagnosis in order the first two weeks, with little benefit total course is prescribed. Patients are to obtain the best outcome. Prednisone after four to six weeks.2 also offered intratympanic dexa- (1 mg/kg/day up to 60 mg max), as a methasone injections (1 cc of 10 single dose for 10–14 days is currently Changes to treatMent mg/mL) for at least three daily injections recommended by the American options until hearing improvement plateaus. If Academy of Otolaryngology. Despite their widespread use, there is hearing improvement continues, then little consensus on the effectiveness of the injections continue until audiologic Other commonly used steroids include oral steroids in ISSNHL. High-dose testing reveals no further improvement. methylprednisolone, prednisolone, and administration of systemic steroids can One major issue which has still not be dexamethasone, depending on raise risks of adverse effects, such as fully addressed is the window of physician preference. Steroids were first avascular necrosis of the femur opportunity in which either oral or shown to have beneficial effects by head, immune suppression, endocrine intratympanic corticosteroid treatment Wilson et al., who demonstrated that problems, osteoporosis, glucose will continue to have any effect. Our patients receiving oral steroids intolerance, or weight gain.3 To avoid centre uses the 14–21 day window- experienced a significantly greater return these side effects, recent studies have patients presenting after that period are of spontaneous hearing (61%), as proposed transtympanic treatment be not typically offered any treatment. compared to those receiving placebo used as the sole initial treatment for (32%). This is believed to have benefit ISSNHL, with studies showing this ConCLusion due to research showing steroids blunt a protocol to be non-inferior to Although controversial, the use of oral cellular inflammatory cascade that conventional oral steroids.4,12 However, steroids in the initial treatment of occurs ISSNHL.4,8,9 there are numerous downsides to this ISSNHL has been considered by many approach; transtympanic steroids can to be the gold standard of care. Current The initial use of transtympanic cause patient discomfort, are more research suggests that transtympanic injections of glucosteroids were expensive, inconvenient to inject and corticosteroid treatment increases recommended as salvage therapy if carry a risk of otomycosis.3 concentration in the cochlear fluids. patients do not experience an increase in Therefore in the philosophy of hearing recovery within 10 days of the Preliminary work has suggested that maximizing corticosteroid concentration initial treatment. However, there is administration of glucosteroids by in the inner ear to minimize permanent limited research to support dosing perfusion through a round window damage, we advocate a combined oral regiments for salvage therapy.10 catheter can deliver a higher and intratympanic corticosteroid concentration of steroid to the inner ear treatment paradigm in patients prognosis and improve hearing when compared to diagnosed with SSNHL. The prognosis of ISSNHL is dependent tympanic membrane injection. This on a variety of risk factors including delivery method can avoid the side referenCes demographics, duration of hearing loss, effects caused by systemic steroid use 1. National Institute of Deafness and Other 13,14 Communication Disorders (NIDCD). Sudden severity of hearing loss, speech and avoid tympanum perforation. deafness. 2003. http://www.nidcd.nih.gov/ discrimination scores, age, presence of health/hearing/pages/sudden.aspx. Accessed vertigo, associated symptoms, and Currently, the Sunnybrook approach October 26, 2012. 11 2. Stachler RJ, Chandrasekhar SS, Archer SM, et audiogram characteristics. Of all involves an audiogram to confirm al. Clinical practice guideline: sudden hearing demographic factors studied, advanced hearing loss, followed by blood work to loss. Otolaryngol Head and Neck Surg age (>60 years in most studies) has been rule out infectious processes if clinically 2012;146(3):S1–S35.
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3. Lim HJ, Kim YT, Choi SJ. Efficacy of 3 different vs intratympanic corticosteroid therapy for 11. Kara E, Cetik F, Tarkan O, et al. Modified steroid treatments for sudden sensorineural idiopathic sudden sensorineural hearing loss. intratympanic treatment for idiopathic sudden hearing loss: a prospective, randomized trial. JAMA 2011;305(20):2071–79. sensorineural hearing loss. Eur Arch Otolaryngol Head and Neck Surg 2013; 8. Conlin AE, Parnes LS. Treatment of sudden Otorhinolaryngol 2010;267(5):701–7. 148(1):121–7. sensorineural hearing loss, I: a systematic 12. Piccirillo JF. Steroids for idiopathic sudden 4. Rauch SD. Clinical practice. Idiopathic sudden review. Arch Otolaryngol Head Neck Surg. sensorineural hearing loss. JAMA sensorineural hearing loss. N Engl J Med 2008; 2007;133(6):573–81. 2011;305(20):2114–15. 359(8):833–40. 9. Roebuck J, Chang CY. Efficacy of steroid 13. Wang Y, Ren J, Lu Y, et al. Evaluation of 5. Kuhn M, Heman-Ackah SE, Shaikh JA, et al. injection on idiopathic sensorineural hearing intratympanic dexamethasone for treatment of Sudden sensorineural hearing loss: a review of loss. Otolaryngol Head and Neck Surg refractory sudden sensorineural hearing loss. J diagnosis, treatment, and prognosis. Trends in 2006;135(2):276–79. Zhejiang Univ Sci B 2012;13(3):203–8. Amplification 2011;15(3):91–105. 10. Shemirani NL, Schmidt M, Friedland DR. 14. Spear SA, Schwartz SR. Intratympanic steroids 6. Neely JG, Ortmann AJ. Sudden sensorineural Sudden sensorineural hearing loss: an for sudden sensorineural hearing loss: a hearing loss and delayed complete evaluation of treatment and management systematic review. Otolaryngol Head and Neck spontaneous recovery. J Am Aca Audiol 2012; approaches by referring physicians. Surg 2011;145(4):534–43. 23(4):249–55. Otolaryngol Head and Neck Surg Canadian Hearing Report 2012;8(3):15-17. 7. Rauch SD, Halpin CF, Antonelii PJ, et al. Oral 2009;140(1):86–91.
FEATURE CAA MEMBER BENEFIT Research Grant for Clinical Investigators
Do you have a question you want answered?
Do have the desire to learn more about the research process?
Do you want to see your name in lights (or at least on a publication)?
The Canadian Academy of Audiology (CAA) Research Grant for Clinical Investigators will provide support, both nancial and practical, to clinical audiologists wanting to investigate a unique research question.
Deadline for submission is August 15, 201
Contact [email protected] for more information.
Canadian Academy of Audiology Heard. Understood.
Académie canadienne d’audiologie Entendus. Compris.
www.canadianaudiology.ca/researchgrant
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16th Annual CAA Conference and Exhibition October 16-19, 2013 Delta St. John's Hotel and St. John's Convention Centre St. John's, Newfoundland and Labrador
www.canadianaudiology.ca/conference2013
researCh and deveLopMent foCus |
Noise Reduction to Achieve Quality ABR Measurement By André Marcoux, PhD and Isaac Kurtz, MHSc, PEng [email protected]
About the Authors André Marcoux, PhD, adjunct professor, Department of Audiology and SLP, University of Ottawa; chief audiologist and president, The Sound Room Hearing Centres; www.thesoundroom.ca. Isaac Kurtz, MHSc, PEng, vice-president of research and technology, Vivosonic Inc.; www.vivosonic.com.
aBstraCt Canada is a leader in the development of auditory brainstem response (ABR) technologies that enhance response detection. In this article, we examine the clinical challenges associated with ABR measurements and uncover advanced technologies developed by Canadian researchers and engineers that offer noise reduction capabilities essential for achieving quality ABR measurements. These advanced technologies are transforming hearing health care around the world.
ost audiologists would agree that microvolts are acquired from the from sources with frequencies of 20 to Mnoise is the foremost frustration auditory nerve and brainstem pathways. 30 Hz up to 2500 Hz – the frequency with clinical auditory brainstem These minute responses travel to a range of a typical ABR signal. Thus, it is response (ABR) measurements. In this recording device to be processed. From helpful to recognize potential sources of context, noise refers to interference from the point of data acquisition to noise and understand how they might be electromagnetic and myogenic sources processing of the signal, there is ample introduced into an ABR waveform. which make it challenging to recognize opportunity for the ABR to be and detect the true response in ABR contaminated by physiological artifacts Physiological Artifacts waveforms. Whether employing ABR for from the patient, and extraneous artifacts There are numerous sources of neurodiagnostics, for estimating hearing and interferences in the environment. physiological noise generated voluntarily ability, or for screening, noise is a When the amplitude of the recorded or involuntarily by the adult or child common and persistent issue. response shows more than 20 being assessed. Muscular activity or microvolts, it is certain that what is movement, even from a fragile newborn, As an electrophysiological measurement shown is not ABR, but noise. can produce significant artifact that which requires information be collected interferes with the much smaller ABR. A “far field,” at a distance, ABR is extremely CoMMon sourCes of noise patient who is relaxed and motionless susceptible to contamination. With (interferenCe) still has small EMG activity in the area of electrodes placed on the patient’s scalp, Noise is everywhere. ABR recordings are the electrode sites such as the forehead, minute responses of 0.05 to 0.5 particularly vulnerable to interference mastoids and scalp, as well as EOG
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 19 | arising from the eyes, ECG from the Stapells1 cautions that ABR recordings of pumps, monitors, etc. is our #1 heart, and EEG from the brain. All of insufficient quality may mean that an problem. Much more time is spent these sources lead to unwanted noise in ABR wave V is identified as “present” trying to solve electrical interference the recordings. It is impossible to when its amplitude is not significantly issues than in actual test time.”2 When eliminate their effects entirely, but it is greater than the background noise. Or, the source of noise cannot be identified possible to significantly reduce them a common mistake is to indicate a “no or eliminated, the patient may need to through good clinical practice and response” when the recording is too be moved to a less noisy environment, advanced ABR technologies. noisy and the residual EEG noise is or assessed in a shielded room or greater than a typical threshold Faraday cage. Motion Artifacts response. Artifacts due to motion are the result of Cannot Complete Assessment electrode leads moving during data Lengthy Measurement Period In some cases, it is simply not possible acquisition. Often this is caused by In noisy environments, when to reduce noise to acceptable levels to patient movement or when adjustments conventional averaging of waveforms is obtain quality recordings. This is a to the leads are made. used, measurement must continue for frequent occurrence in environments excessively long periods of time in order with high electromagnetic interference, Recording Environment to accurately detect the response. This is such as the neonatal intensive care unit Sources of extraneous noises in our problematic when assessing infants, (NICU) or operating room (OR). Even environment are typically the most children, or other patients who may be when potential sources of interference difficult to identify and mitigate. uncooperative. Only partial data may be have been removed and non-essential Frequently the presence of electro- collected and a follow on appointment equipment powered off, noise may magnetic noise from nearby equipment, must be arranged to complete the remain so high that testing must be conducted power line noise, and radio assessment adding to costs and abandoned. frequency interference, all serve to inconvenience for all concerned. contaminate the ABR recording. ConventionaL Means of Without proper shielding of wires Sedation of Infants and Young Children reduCing noise and/or the recording environment, Sedation or anesthesia is often used to How is noise extracted from the electrode leads are prone to field minimize contamination of the ABR response that we are trying to measure? artifacts. Inadequate grounding invites recording from myogenic artifacts Following good clinical practice, along unwelcome electrical pickup from present when infants and young children with built-in noise reduction features of circuitries in the room and the influence are awake and alert. There is an entire the ABR measurement instrument, it is of 50/60 Hz noise and harmonics can body of literature that examines the possible to reduce noise in the ABR. appear in the waveform. effects of sedation. For the most part it is Conventional methods for reducing safe, yet there remains a certain amount noise are mentioned here. ConseQuenCes of of risk related with its use. “Sedated ABR (too MuCh) noise procedures are costly, time-consuming Shielding Too much noise in ABR recordings has and require constant patient monitoring When noise and interference cannot be a number of consequences. Here are the during the procedure.”2 In a recent report mitigated further by moving or major ones. by the Pediatric Sedation Research powering off equipment in the test Consortium,3 auditory brainstem environment, shielding is sometimes the Misinterpretation of ABR response was identified as one of the only means to ensure adequate Artifact and interference make it difficult procedures for which sedation was immunity. This can be an effective, but to interpret waveforms and can result in commonly used. Data from 114,855 costly solution to the problem of reduced accuracy of wave recognition pediatric sedations indicated that extraneous noise. and latency measurement. When monitoring guidelines published by the estimating hearing ability or hearing American Academy of Pediatrics (AAP) Natural Sleep and Sedation loss, specifically at lower stimulus were followed in only 52% of cases. Natural sleep and sedation are common intensity levels, the amplitude of the approaches used with infants and young waveform may be similar to that of the Time Spent Reducing Noise children to manage muscular activity. In noise making it difficult to interpret. “Electrical interference from feeding general, it is preferable to assess an infant
20 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | in natural sleep over the risks of symmetrical. This is needed for deemed to have too much noise and are sedation. Natural sleep often requires common-mode rejection, otherwise not included in the averaging. While this that an infant be deprived of sleep before there is difficulty obtaining an acceptably reduces the impact of noisy responses on the appointment, and still it may be low level of EEG noise when recording ABR morphology, too many rejected necessary to wait for the infant to fall ABR. sweeps can prolong recording time. As asleep before testing can proceed. sweeps are rejected, more data must be Particularly in the case of older infants Averaging collected for sufficient averaging to and young children, natural sleep is Signal averaging is possible because ABR occur. frequently not an option. Rather than is time-locked to the stimulus, with each manage the myogenic artifact arising repeated stimulation eliciting the same Pause Equipment from an active or uncooperative child, response. Noise, on the other hand, is Signal processing and noise cancellation many clinics proceed directly to very random and has no regular pattern. techniques are usually inadequate to sedation, providing that sedation is not By presenting the same stimulation over overcome the effects of myogenic artifact contraindicated and caregivers consent and over again, and averaging the such as a baby stirring or a child to this procedure. responses together, the ABR waveform squirming. When patient movement should emerge from the noise. causes too much noise, it may be more Patient Posture and Positioning Increasing the number of stimulus practical to simply pause data To reduce muscular activity and provide presentations, or sweeps, improves acquisition until the movement support for the neck, adult patients are waveform morphology. Averaging can be subsides. typically asked to lie supine on a bed, terminated as soon as a clear ABR close their eyes, and relax as much as waveform is visualized. Repeatability of advanCed aBr teChnoLogies possible. In most cases, this is sufficient the waveform is required to confirm the that reduCe noise to minimize muscular noise. However, presence or absence of a response. If the Noise in ABR measurements can be when patients are aware that the measurement instrument has two significantly reduced through innovative assessment seeks evidence of a tumour, recording buffers, repeatability is easily technologies developed by researchers they are understandably agitated and as determined by visually comparing the and engineers in Canada. The three a consequence generate undue levels of averaged waveforms in each buffer. technologies described here have been muscular artifact which is not easily Statistical tools can further provide an developed by Vivosonic Inc., a leader in extracted from the signal. objective validation. technologies that enhance ABR detection. Electrode Impedance Conventional averaging techniques To obtain cleaner recordings, it is typically weight all sweeps equally so The combination of these technologies common practice to scrub and exfoliate that sweeps with higher amplitudes effectively minimizes the need to sedate the skin of the patient with a mild (high noise) have the same impact on infants and young children for ABR abrasive before applying electrodes to the waveform morphology as sweeps assessment,5 is effective in managing the site. This serves to reduce electrode with lower amplitudes (less noise and electrical and artifacts in places with impedance which can significantly closer to an ABR). Note that more high electromagnetic interference such impact EEG quality. “The impedance advanced “weighted” averaging as the NICU6–8 and OR,2 permit ABR does not affect the ABR itself, but the techniques, such as Kalman Weighted measurement via tele-audiology,9,10 help larger the impedance, the larger the Averaging, weight sweeps according to to identify false indications of noise- amount of pickup of external noise content so that noisy responses induced hearing loss,11 and provide electromagnetic interference and of have less of an impact on the waveform more accurate ABR under non-ideal artifacts from movement of the electrode morphology. conditions compared to conventional leads.”4 A low electrode impedance of 3 methods.6,7,12,13 or 4 kOhm is often recommended, with Artifact Rejection impedance difference between electrode When conventional averaging is used, it “We were able to get valid passing pairs not more than 1 kOhm. Acceptable is typical to set an artifact rejection level newborn hearing screenings on infants ABR recordings can be obtained with of a certain voltage such as 20 that were awake and in electrically higher impedances providing the microvolts. Sweeps with amplitudes complex locations (running isolette and impedance difference is balanced and greater than the rejection level are being held by a parent/nurse).” And,
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Figure 1. Amplitrode with built-in pre-filtering and Figure 2. Vivolink wireless technology provides convenient testing. amplification at the recording site.
“Accurate recordings were obtained picking up electromagnetic noise and chance to pick up undesirable noise. regardless of whether or not the baby other contamination, the result is the was awake, asleep, in a crib or running recording of a more robust ABR signal.14 WireLess teChnoLogY isolette.”7 Technology that can provide complete In contrast, the of lack in-situ wireless communication between the “There is much less, if any, interference amplification in conventional systems recording platform and the electrodes from monitors and other OR equipment. means that amplification occurs after the has valuable benefits. As a battery- Test time is easily cut in half.”2 signal has had to travel from the powered unit, the VivoLink is immune electrode, along a cable, all the way to a to line noise. Furthermore, elimination aMpLitrode preamplifier. With the cables acting as an of wires reduces susceptibility to This patented technology provides two antenna, there is a great deal of electromagnetic interference in the distinct innovations: filtering of the ABR opportunity for noise to be introduced recording environment. Overall, this before amplification, along with from sources present in the recording means there is less noise to manage amplification of the signal directly at the environment. Line noise and additional which translates to very clean waveforms recording electrode site (Figure 1). By wires also contribute to contamination of in very little time. prefiltering the signal, the effects of the signal. Now, when the signal reaches EOG, ECG, motion artifact, and RF are the preamplifier, it is contaminated with Wireless recording also makes it possible almost completely eliminated. Gain all sorts of noise which is subsequently to collect data while a baby is held, adjustments are no longer needed, and amplified. strolled, or nursed – untethered to the risk of signal saturation is reduced. equipment. In the case of high-risk Furthermore, by amplifying the signal The patented Amplitrode eliminates babies in the NICU, the VivoLink “in situ” (at the recording site), sources many of the problems related to enables babies to be tested inside an of noise from the recording environment extraneous noise by prefiltering and incubator while the recording platform are reduced. Instead of an unamplified amplifying immediately at the site of data remains outside. The incubator may signal travelling along the electrode leads acquisition, before the signal has had a even be closed shut while testing is in
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techniques, there is no artifact rejection. Practices During Pediatric Procedural Sedation: Instead, sweeps are included in the A Report from the Pediatric Sedation Research Consortium. Arch Pediatr Adolesc Med. recording and assigned a weighting 2012;166(11):990–98. based on its noise content. Groups of 4. BC Early Hearing Program (revised by Hatton sweeps with less noise are assigned a J, Hyde M, Stapells DR). Audiology Assessment Protocol, Version 4.1, November 2012. much greater weighting than sweeps 5. Hall JW III, Sauter T. Clinical Experience with with higher amplitude noise. Thus, New Technology For Recording Un-Sedated noisy responses have less of an impact ABRs. Poster presentation at AudiologyNOW! on the waveform morphology. By 2010, San Diego, CA, April 14-17, 2010. 6. Brown DK, Hunter LL, Baroch K, Eads E. including all sweeps, and by weighting Comparison of Auditory Brainstem Response them according to the noise content, we Systems in the NICU Population. Poster can actually obtain a much clearer ABR presentation at AudiologyNOW! 2011, Chicago, IL, April 6-9, 2011. waveform in less time. 7. Johnson K. Universal Newborn Hearing Screening in the NICU Population Using New In addition to averaging, adaptive Features of the Vivosonic Integrity ABR Unit: processing methods are used throughout Assessing the Correlation Coefficient as a Function of the Number of Sweeps Collected. the measurement. The system Proceedings of University of Kansas recalculates all weightings according to Intercampus Program in Communicative the noise content and the relationship Disorders. Au.D. Research Day, April 27, 2012. between sweeps (covariance). This very 8. Walker B. Clinical Significance of Advanced ABR Technology for Newborn Hearing active and unique dynamic weighting Screening Programs. Hearing Review Products, system provides much cleaner March 2012. waveforms in much less time. 9. McVicar S, Randall K, Wnek S, Bleazard C, Ladner D. Tele-Audiology in Utah: Our Efforts Figure 3. SOAP Adaptive Processing enables to Reduce Newborn Hearing Screening Loss to ABR without risks of sedation. finaL thoughts Follow-up. AMCHP 2013 Annual Conference, Mastering ABR measurement is a Washington, DC, February 9-12, 2013. progress, with the recording platform up worthwhile undertaking in order to 10. See C. and Seeliger E. TeleAudiology: The Key to Serving Rural Populations. EHDI 2012 to 10 metres (30 feet) away. This provide a comprehensive diagnostic Conference, St. Louis, MO, March 5-6, 2012. technology also permits children and picture of auditory function. Good 11. Steinman A. Use of the Vivosonic Integrity adults the freedom to move and be clinical practice combined with V500 System to Identify False Indications of tested in comfort (Figure 2). Noise Induced Hearing Loss (unpublished technological advancements can help to document). Based on an instructional overcome frustrations with noise in data document by Holdstein Y. Definitive auditory soap adaptive proCessing acquisition and interpretation, and evaluation of workers exposed to excessive (an evoLution of kaLMan ultimately aid in obtaining quality ABR noise at work. Prepared for Labour Ministry, Weighted averaging) Israel, 10/12/2009. measurements. 12. Meyer D, Moskop J, Winston A, Schupback J. This is perhaps the most innovative ABR Results in Quiet and Active Subjects. technology for noise reduction in referenCes Poster presentation at AudiologyNOW! 2011, evoked potential responses. SOAP 1. Stapells DR. Frequency-Specific ABR and ASSR Chicago, IL, April 6-9, 2011. 13. Gerhart MJ, Hall JW III, Black AL. Evaluation Adaptive Processing is a combination of Threshold Assessment in Young Infants. Phonak Sound Foundations 2010 manuscript of the Vivosonic Integrity Device for Auditory patented and proprietary technologies (pp. 67-105). An updated version of Brainstem Response Measurement. Poster that adaptively reduce the myogenic and Frequency-specific threshold assessment in presentation at AudiologyNOW! 2010, San electromagnetic noise in ABR. It is an young infants using the transient ABR and the Diego, CA, April 14-17, 2010. 14. Kurtz I and Sokolov Y. Reducing the effect of evolution of signal processing algorithms brainstem ASSR. In R.C. Seewald and A.M. Tharpe (eds.), Comprehensive handbook of electric and magnetic fields on auditory evoked that use Kalman Weighted Averaging. pediatric audiology (pp.409-448). San Diego: potentials. Presented at 28th Annual Midwinter Together with the Amplitrode and Plural Publishing, Inc. Meeting of Association for Research in Otolaryngology, New Orleans, LA, February VivoLink wireless technology, SOAP 2. Horsch M. Newborn Hearing Screening: Utilization of Non-Sedated ABR to Assist with 19-24, 2005. provides superior response detection Loss to Follow-up. Presentation at Canadian Hearing Report 2012;8(3):19-23. under non-ideal conditions and AudiologyNOW! 2011, Chicago, IL, April 6-9, facilitates non-sedated ABR 2011. measurement (Figure 3). 3. Langhan ML, Mallory M, Hertzog J, Lowrie L, Cravero J for the Pediatric Sedation Research As with Kalman Weighted Averaging Consortium. Physiological Monitoring
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Audiological Outcomes for Children Who Wear Hearing Aids
By Marlene Bagatto, Sheila Moodie, Christine Brown, April Malandrino, Frances Richert, Debbie Clench, Doreen Bartlett, Richard Seewald, and Susan Scollie [email protected]
About the Authors Marlene Bagatto (pictured), Sheila Moodie, Richard Seewald, and Susan Scollie are with the Child Amplification Laboratory, Western University, London, Ontario. Christine Brown and Frances Richert are with the Speech & Hearing Clinic, Western University. April Malandrino and Debbie Clench are with theHumber River Regional Hospital, Toronto, Ontario. Doreen Bartlett is with the School of Physical Therapy, Western University.
(Adapted from a poster presented at the International Hearing Aid Research Conference, Lake Tahoe, California, August 2012)
BaCkground programs. A lack of well-normed clinical PEACH is used in its rating scale format,4 The primary goal of Early Hearing tools that are valid and feasible may have and applied in the second developmental Detection and Intervention (EHDI) been a barrier to outcome evaluation in stage. programs is to provide effective children with hearing aids. intervention by six months of age to purpose maximize the infant’s natural potential to The University of Western Ontario This study examines how children with develop language and literacy skills. Pediatric Audiological Monitoring aided PCHI perform on the functional Intervention with hearing aids is a Protocol Version 1.0 (UWO PedAMP)2 outcome measures within the UWO common choice among families of consists of a battery of outcome PedAMP. The LittlEARS is a 35-item infants identified as having permanent evaluation tools and related support questionnaire that assesses the auditory childhood hearing impairment (PCHI). materials. This protocol aims to support development of infants during the first Audiologists have access to scientifically clinical, systematic evaluation of two years of hearing. The PEACH Rating based strategies and clinical tools to auditory-related outcomes for infants, Scale is a 13-item questionnaire that ensure the hearing aids are fitted toddlers, and preschool children with assesses auditory performance in quiet appropriately to the infant.1 PCHI who wear hearing aids. This and noisy situations for toddlers and includes both clinical process measures preschool children. Normative values pediatriC outCoMe and functional outcome measures in a exist for normal hearing children for both evaLuation two-stage process by developmental questionnaires.5,6 However, few data for Outcome evaluation is a key component level. The functional outcome measures children who are followed within an of the pediatric hearing aid fitting included in the protocol are the EHDI program are available. This work process; however, there has been little LittlEARS Auditory Questionnaire3 and characterizes LittlEARS and PEACH consensus on best practices for functional the Parents’ Evaluation of Aural/Oral scores for children with PCHI who (a) are outcome measurement in EHDI Performance of Children (PEACH).4 The enrolled within an EHDI program; and
24 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | taBLe 1. desCription of infants, toddLers and presChooL ChiLdren With aided pChi invoLved in this studY
Number of Pure Tone Average Mean Age Age Range Typically Developing Comorbidities Complex Factors Participants (range in dB Hl) (months)* (months)* (%) (%) (%) 116 21.2–117.5 35.6 3.6–107.1 36.2 23.5 40.9 *Chronological age. uses provincial protocols for the provision of hearing aids,1 which include fitting the hearing aids to the Desired Sensation Level (DSL) version 5.0a prescriptive algorithm.7 Audiometric and medical profiles of the children varied, along with follow-up details.
partiCipants Table 1 provides the number of participants involved in this study in one of three groups: (1) typically developing; (2) comorbidities; and (3) complex factors. Children with comorbidities were born prematurely and/or had other identified medical issues besides hearing loss. Complex factors were logged to track non-medical issues that may impact overall outcome with intervention (i.e., late identification, late fitting, inconsistent hearing aid use).
resuLts: auditorY deveLopMent and auditorY perforManCe Regression analyses were conducted on each group separately to determine the effect of age on the overall PEACH Figure 1: littlEARS scores (y-axis) by age (x-axis) and regression lines from typically developing children score. For all children who were (circles), children with comorbidities (squares) and complex factors (triangles). The solid line represents typically developing, scores varied the minimum normative values. Various dashed lines indicate the regression for each data set. significantly with age (R2=0.19; F=5.60, df=25, p<0.05; Figure 1). This is consistent with published data.5 In a (b) reflect the general population of audiologists at four clinical sites second analysis, only typically children typically followed in a pediatric administered the LittlEARS and PEACH developing children older than 24 audiology outpatient clinic. to caregivers of infants, toddlers, and months were included, and the effect of preschool children with aided PCHI. age was not significant (R2=0.09; F=1.57, Method The patients were seen during routine df=16, p=0.23; Figure 2). Comparing the Data were obtained as part of a clinical care through Ontario’s Infant curves indicates that there is no longitudinal observational study in Hearing Program (OIHP) over a period significant age effect on overall PEACH which outcomes were logged for all of 18 months. The OIHP follows scores after 24 months of age. This may patients at participating sites. Pediatric children from birth to age six years and support the use of raw (rather than age-
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Figure 2. PEACH scores by age (filled circles) and Figure 3. PEACH scores by age from the three subgroups: typically regression lines from typically developing children developing (circles), comorbidities (squares) and complex factors with aided PCHI. The solid line is an s-shaped (triangles). Symbols represent average percentage scores for each regression for children of all ages and the dashed subscale and vertical bars represent the standard deviation around line is a linear regression for children older than the mean. 24 months. corrected) scores for children older than ŋ2=0.179) but presence of complexity typical auditory performance (PEACH). 24 months of age and typical was not (F [2,70] = 0.37, p > 0.05, ŋ2 = Children with comorbidities and development. 0.011). Univariate effects confirmed that complex factors display different children who are typically developing or auditory development trajectories on the Overall PEACH scores for all children in have complexities did not differ on their LittEARS compared to their typically the study ranged from 13.64 to 100% PEACH scores for either the Quiet developing peers. PEACH scores for (mean=74.47%; SD=16.87). Descriptive (F [2,73] = 0.39, p > 0.05) or Noise typically developing children in this statistics are reported for 17 typically (F[2,73] = 0.53, p >0.05) subscales. sample are approaching the score developing children, 16 children with However, the degree of hearing loss had achieved by normal hearing children comorbidities and 32 children with a significant impact on PEACH scores for (90%) by age three years.5 Regression complex factors related to hearing aid use the Quiet (F [1,73] = 9.59, p <0.05) but analyses indicated there is no age-related (Figure 3). These scores differ markedly not the Noise (F [1,73] = 1.03, p >0.05) effect on overall PEACH score for from published normative ranges5 for subscales. Regression analysis of the children who are typically developing this scale for typically developing entire sample revealed a decrease in and older than 24 months: this may children. overall PEACH scores with increasing simplify clinical use of the tool as it hearing loss (R2 = 0.07; F = 4.99, df = 72, obviates age-corrected scoring. Further A multivariate analysis of covariance p = 0.03). analysis indicated that the degree of (MANCOVA) was conducted to hearing loss impacts scores on the determine the impact of degree of suMMarY and CLiniCaL PEACH but complexity does not. hearing loss and complexity (three-level iMpLiCations independent variable) on the scores for In summary, typically developing This study contributes to a better the PEACH Quiet and Noise subscales. children who were identified and fitted understanding of functional outcomes Results indicated that the multivariate early with high quality amplification for children within an EHDI program effect of degree of hearing loss was reach age-appropriate auditory develop- using a systematic approach to outcome significant (F [2,70] = 7.43, p < 0.05, ment milestones (LittlEARS) and display evaluation.
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aCknoWLedgeMents This work was supported by The Canadian Institutes of Health Research (M. Bagatto 220811CGV-204713-174463) and the Ontario Research Fund, Early Researcher Award (S. Scollie).
referenCes 1. Bagatto M, Scollie S, Hyde M, and Seewald R. Protocol for the provision of amplification within the Ontario Infant Hearing Program. Int J Audiol STUDENT BURSARY AWARD
2010:49:S70–79. 2. Bagatto M, Moodie ST, Malandrino A, Richert F, Clench D, and Scollie S. The Do you or someone you know need support to University of Western Ontario Pediatric Audiological Monitoring Protocol attend the annual CAA conference? (UWO PedAMP), Trend Amplif 2011;15(1):34–56. 3. Tsiakpini L, Weichbold V, Kuehn-Inacker H, Coninx F, D’Haese P, and Eligible students include: Almadin S. LittlEARS Auditory Questionnaire, MED-EL, Innsbruck: Austria; 2004. ~ Students in a Canadian audiology program 4. Ching T and Hill M. The Parents’ Evaluation of Aural/Oral Performance of attending their penultimate year of study Children (PEACH) Rating Scale, Australian Hearing, Chatswood, New South Wales, Australia; 2—5. http://www.outcomes.nal.gov.au/LOCHI ~ Canadian students who are studying %20assessments.html. audiology abroad, any year 5. Ching T and Hill M. The parents’ evaluation of aural/oral performance ~ Non-audiology students who want to of children (PEACH) scale: Normative data, J Am Acad Audiol 2007;18:220– 235. attend the conference 6. Weichbold V, Tsiakpini L, Coninx F, and D’Haese P. Development of a parent questionnaire for assessment of auditory behaviour of infants up to two years Visit the www.canadianaudiology.ca/professional.html of age, Laryngo-Rhino-Otol 2005;84:328–34. (under NEWS AND EVENTS) for the application form, details, 7. Scollie S, Seewald R, Cornelisse L, et al. 2005. The Desired Sensation Level and requirements or contact [email protected]. multistage input/output algorithm. Trends Amplif 2005;9(4):159–97. Deadline June 30, 201 Canadian Hearing Report 2012;8(3):24-27.
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was published in CHR, you will find it at the Andrew John Publishing Inc. is pleased to announce a totally new CHR website. searchable experience coming ■ Download select articles. soon where you will be able to ■ Forward select articles to colleagues. find some of hearing health ■ Print articles. sciences’ best articles. ■ Catch up on the latest news.
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Headsets – Are They Damaging your Hearing?
By Alberto Behar, PEng and Gabe Nespoli, BSc, MA Ryerson University [email protected]
About the Authors Alberto Behar is a professional engineer and certified industrial hygienist. He holds a diploma in acoustics from the Imperial College and has been the recipient of several fellowships, including one from the Fulbright Commission (USA) and the Hugh Nelson Award of Excellence in Industrial Hygiene (OHAO, Canada).
He is lecturer at Dalla Lana School of Public Health, University of Toronto and a board certified member of the Institute of Noise Control Engineering. Alberto is a chairman and member of CSA and ANSI committees and working groups and is also the Canadian representative at two ISO Working Groups.
Gabe Nespoli is research operations coordinator at Ryerson University and lab manager (SMART Lab) at Ryerson University
eadsets are headphones with an disturbing others, or when trying to Hattached microphone that allows block out environmental noise while the user to communicate. working or playing on the computer. Different headsets provide different We see them all the time in fast food take- amounts of attenuation for different outs (sometimes with one cup only) so applications. High attenuation headsets that the worker can take your order while may also act as hearing protectors. walking around. On a noisy shop floor they are used to attenuate background When wearing a headset, there are two noise while enabling communication sources of sound involved: enviro- with fellow workers or supervisors. Some nmental (background) noise and an truck drivers wear headsets to listen to audio signal (that can be speech or the radio or communicate with the music). dispatch centre, freeing their hands for driving. They are also used in call centres, The headset’s cups attenuate environ- airport control towers, and construction mental noise, while the signal is routed Figure 1. Example of headset. sites. We even use them at home when directly into the ears of the listener we want to listen to TV without through the loudspeakers situated in the
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Figure 2. The noise level inside the headset. Figure 3. Set-up for the experiment. cups. Usually, the user adjusts the signal measured attenuation 0.7 dBA), our speech differently. to a comfortable listening level for speech results show that the addition of the or music. speech signal increased the sound level The results clearly show that if a person by as much as 5 dBA. For example, if the has to wear a headset in the presence of Can the use of headsets background noise level is 85 dBA, the noise, he has to make use of a high daMage our ears? level inside the headset could be as high attenuation headset to avoid high noise How much does the level of the signal as 90 dBA (background noise + speech levels. This way, the associated risk of have to be raised above the background signal). hearing loss is greatly reduced. noise to ensure comfortable intelligibility? At Ryerson University, 22 The high attenuation headset used in our The three main conclusions of the study students were individually presented experiment reduced the background are: with a speech signal (non-related noise level by an average of 13.5 dBA. sentences) through a headset. They were Therefore, a background noise level of 85 1. In high noise environments, asked to adjust the level to be able to dBA would be reduced to 71.5 dBA. headsets must be of the high understand it properly. Three different Including the speech signal the total attenuation type. types of background noise – babbling sound level inside the headset would be 2. The increase in noise exposure due speech, industrial noise and construction 76.5 dBA (that is, the background noise to the signal is on the order of 5 dBA noise – were introduced in a sound- attenuated by the headset, plus the 5 dBA on top of the background noise treated room where the tests were increase due to speech). attenuated by the headset. performed. Two headsets were used: one 3. This increase is highly dependent of with high attenuation and one with low It was found that the resulting sound the type of noise in the environment attenuation. levels in the headset are strongly (speech, industrial, construction, dependant on the type of background etc.). For the low attenuation headset (average noise, since different noise spectra mask Canadian Hearing Report 2012;8(3):28-29.
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 29 Foreword by Ross Roeser, PhD: Is Higher Really Better and lower Worse?
In the following article, originally published in the March 2013 edition of the International Journal of Audiology,1 Jim Jerger, PhD, provides us with an historical perspective on one of the most often used and valued diagnostic tools in audiology: the audiogram. In his article, Dr. Jerger describes the beginnings of the development of the audiogram and, based on traditional scientific graphics, how it became backwards or upside-down. Before reading this article, I personally never questioned the way the data on the audiogram appears, because this is the way it was presented to me when I was first introduced to audiometry and the audiogram – it never occurred to me to think that it was backwards. But, based on conventional logic, Dr. Jerger makes the point clear that the audiogram truly can be considered upside-down.
Along these lines, one thing that has always been confusing is the terms used to describe results from pure-tone threshold audiometry. Some use “higher” and “lower” to represent the symbols that appear on the audiogram form, so that higher means poorer hearing and lower means better hearing. However, psycho- acousticians tend to use the term “lower” to mean better hearing and “higher” to mean poorer hearing. As a result, one can totally miss the meaning of information that uses higher or lower when describing audiometric thresholds.
When such terms are used, it is always best to ask for clarification. Otherwise, the audiologist who is pleased to know that a patient’s thresholds are higher will be disappointed to learn that hearing has worsened, rather than improved. Better yet, to prevent confusion on these terms, the convention should be to avoid using them, and refer to either better or poorer hearing or thresholds. That way, there is no confusion about the intended meaning.
No matter how we view the audiogram, even with its known limitations, it is considered the “gold standard” for audiological diagnosis. Virtually every patient undergoing diagnostic audiological testing has pure-tone threshold audiometry, and data are displayed on the audiogram. Dr. Jerger’s article now gives us a clear historical understanding of how the audiogram is the way it is, and makes us think more carefully about how it is displayed.
—Ross J. Roeser, PhD, Editor-in-Chief, IJA
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Reprinted with permission from the International Journal of Audiology
Why the Audiogram Is Upside-Down
By james jerger, PhD
sciences, and his 1953 book, Speech and Hearing in Communication,2 was a virtual bible for serious researchers throughout the second half of the 20th century.
R.L. Wegel (whose photo we were not able to locate) was a physicist who earned his AB degree from Ripon College in 1910. From 1912 to 1913, he worked as a physicist in the laboratory of Thomas A. Edison. In 1914, he joined the Engineering Department of the Western Electric Company in New York City. He worked mainly in the area of telephone Figure 1. Edmund Prince Fowler (1872-1966) Figure 2. Harvey Fletcher (1884-1981) was a transmitters and receivers, but developed was a giant in otology during the first half of the physicist who joined Bell laboratories and an interest in hearing and hearing 20th century and is perhaps best known for his became a pioneer in speech and hearing discovery of loudness recruitment. sciences. disorders as a result of his own intractable tinnitus.3 Wegel is perhaps best known to auditory scientists for his n every new generation of audiology Edmund Prince Fowler (Figure 1) was an collaboration with C.E. Lane on an early Istudents and otolaryngology residents, otolaryngologist who practiced in New study of tone-on-tone masking.4 at least one or two inquisitive individuals York City. He received his MD degree invariably ask why the audiogram is from the College of Physicians and genesis of the audiograM upside-down. Surgeons of Columbia University in forM 1900, then became a member of the The trio – Fowler, Fletcher, and Wegel – Students spend years studying science Manhattan Eye, Ear, & Throat Hospital came together in the New York City area textbooks in which two-dimensional staff and, ultimately, Professor at the in the years immediately following World graphs are virtually always portrayed College of Physicians & Surgeons. War I. Their common interest was the such that the numbers on the vertical Fowler was one of the giants of otology development and evaluation of the first scale increase as they move from the during the first half of the 20th century. commercially available audiometer in the bottom to the top of the page; then they He is perhaps best known to audiologists USA, the Western Electric Model 1-A, encounter audiograms and wonder why for his discovery of loudness recruitment, designed jointly by Fletcher and Wegel the “HL in dB” numbers increase in a but his investigative nature took him into for the American Telephone and downward rather than an upward many other aspects of hearing and Telegraph Company (AT&T) and direction. Basically, the audiogram is hearing loss. employed clinically in the otologic upside down; the values on the vertical practice of Dr. Fowler. axis become smaller, rather than larger, Harvey Fletcher (Figure 2) was a as they move from the bottom to the top physicist who earned his PhD degree Throughout World War I, the research of the graph. from the University of Chicago in 1911, resources of AT&T were focused on and then taught physics at Brigham underwater sound transmission and How this anomaly came about is the Young University in Utah for 5 years. In detection, but when the war ended, story of an interesting collaboration 1916, he moved to the New York City interest returned to the basic study of the among three remarkable individuals: area to join the Bell Telephone hearing and speech processes, and, Edmund Prince Fowler, Harvey Fletcher, Laboratories. Fletcher was an early tangentially, hearing loss, all important to and R.L. Wegel. pioneer in the speech and hearing telephone communication. AT&T
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Figure 3. Wegel’s graphic scheme: A recreated graph of the auditory area, Figure 4. Fowler’s graphic scheme: Method for recording audiometric results including threshold of audibility (Normal Minimum Audibility) and threshold of suggested by Fowler & Wegel in 1922.10 At each frequency, patient’s threshold “feeling” (Maximum Audibility), as described in Wegel’s 1922 paper.11 His original is converted to “percent of normal hearing” by counting the number of terminology is purposely preserved on the figure for the sake of historical sensation units from normal threshold of audibility to patient’s threshold of accuracy. At each frequency, the area between these two boundaries was divided audibility, dividing by number of sensation units from normal threshold of into “sensation units” by Fowler. Each sensation unit was defined by a sound audibility to threshold of feeling, multiplying by 100, and subtracting this value pressure ratio of 10:1. [Based on Wegel 1922,11 Figure 1, p 156] from 100%. The filled squares plot percent-of-normal-hearing results for a person with a hypothetical high-frequency loss. Note that the “percent-of- normal-hearing“ scale conforms to the conventional scientific scheme for reporting data on a two-dimensional graph. Note also that, for the first time, the 100% line – which subsequently became the zero line of the audiogram – was linked to the variation in SPl across frequencies at the threshold of audibility. [Based on Fowler & Wegel 1922,10 Figure 3, p 110] turned, therefore, to its engineering Tuning forks could produce a range of varied to facilitate a threshold search wing, the Western Electric Company, and frequencies, but their use in measuring separately for each ear. to its research wing, the Bell Telephone degree of hearing loss was restricted Laboratories, for the development of an either to a temporal measure (ie, how As the Western Electric 1-A audiometer instrument to measure hearing loss. R.L. long could the patient hear the fork in came into clinical use, our trio of Fowler, Wegel of Western Electric and Harvey relation to how long the examiner could Fletcher, and Wegel began to wrestle Fletcher of Bell Labs took responsibility hear it), or to a distance measure (ie, how with the issue of how to standardize the for the task. When the 1-A audiometer far away from the examiner could the reporting of audiometric thresholds. was ready for clinical evaluation, Wegel patient still hear him).8 Thus, tuning Fowler and Wegel’s first attempt was and Fletcher found a willing collaborator forks interjected a truly mind-boggling presented to otologists in 1922 at the in Edmund Prince Fowler. (Fowler had number of uncontrolled variables. 25th annual meeting of the American previously worked with Fletcher and Laryngological, Rhinological and Alexander Nicholson of Western Electric Use of the intensity dimension – the Otological Society in Washington, DC.10 in the development of a group faintest intensity at which the patient can It was concerned primarily with how to phonograph audiometer for screening just hear the tone – had never been represent thresholds graphically. the hearing of schoolchildren.5) successfully exploited until the electric audiometer became available to There was never a serious issue the saga of the vertiCaL clinicians. (As Alberto Behar9 has concerning representation of the sCaLe emphasized, the exact definition of frequency scale; the well-established It is difficult to imagine from our present- “intensity” in physical acoustics is a musical scale, in which octave intervals day vantage point the terra incognita in complex issue; the term is used here are equally spaced, was readily adopted which this trio worked. Prior to the mostly in the popular general sense of for the horizontal dimension of the invention of the vacuum tube by Lee De “strength of sound.”) Now it was possible graph. But the vertical dimension, the Forest in 1906, there was really no via a telephone receiver to produce a representation of threshold intensity, satisfactory way of controlling and pure tone of known sound pressure underwent a number of iterations. calibrating the amplitude of a pure tone. level, which could be systematically In a 1922 publication, Wegel11 had
32 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | published a graph of the “auditory area” convert any patient’s threshold of numbers ought to increase from bottom – the area between threshold audibility audibility to a “percentage loss” by this to top of the graph. and the sensation of “feeling” across the arithmetic maneuver. audible frequency range. I have recreated We can see in Figure 4 that, if Fowler’s this historic graph in Figure 3. Frequency It was possible to take this one step original concept had been followed, the was represented horizontally at further, reasoned Fowler, by subtracting graph of audiometric results, which came approximately equally spaced octave the percentage loss from 100 to achieve to be called the “audiogram,” would have intervals; intensity was represented “percent of normal hearing”(100% −31% followed standard scientific usage; the vertically on a logarithmic scale of sound = 69%). Figure 4 is based on Figure 3 of values on the vertical scale (percent of pressure level change, ranging from the Fowler and Wegel (1922) paper.10 normal hearing) would, indeed, have 0.0001 to 10,000 dynes/cm2. A The filled squares show the hypothetical moved upward from the lowest to the logarithmic scale of sound intensity was audiometric contour of a person with a highest numbers. At this point, the die already widely accepted in the 1920s, high-frequency hearing loss. This chart, had been cast. The line that came to be based on the earlier studies of the great thought Fowler, gave you the numbers called “zero HL in dB” was fixed at the German psychologists, Ernst Weber and you needed to counsel patients. In his top of the graph and would never change Gustave Fechner.8 It was well agreed, own words: thereafter. among students of audition, that the “strength of sensation” dimension should “This chart gives, perhaps, the most But Harvey Fletcher, a physicist, not a be represented logarithmically. From the practical and logical answer to the clinician, clearly did not agree with the standpoint of scientists like Fletcher and question so often asked by the patient. percent-loss approach. In a lecture and Wegel, the sound pressure level, ‘How much hearing have I left?’ This can demonstration given before the expressed in dynes/cm2, and increasing be read for single frequencies from the American Academy of Ophthalmology logarithmically from small numbers at chart. The physician, as well as the and Otolaryngology in Chicago in the bottom to large numbers at the top patient, is usually interested in the loss, 1925,13 he made the following argument: of the graph, was consistent with or amount retained, of sensory capacity.” scientific tradition. [p 110]10 “In a paper presented before the American Triological Society by Fowler But the story does not end here. Indeed, Interestingly, a similar graphic represent- and Wegel (Audiometric Methods and it has hardly begun. After studying ation was advanced in 1885 by the Their Applications, May 1922), a hearing graphs like Figure 3, Fowler noted that German otologist A. Hartmann of scale was proposed which has been when sound intensity was represented Berlin.8 He displayed duration of hearing objected to by some otologists because it logarithmically, in which each successive at each tuning fork frequency as a is dependent on the threshold of feeling step represented a pressure change ratio percentage of normal duration. The as well as the threshold of hearing. On of 10:1, slightly less than 7 such steps percentages on the vertical scale ranged this scale the percent hearing loss is the separated the threshold of audibility from from 100% at the top of the graph to 0% number of sensation units from the the threshold of feeling in the mid- at the bottom. normal to the patient divided by the frequency (1000 to 3000 Hz) region. number of sensation units from the Fowler described this as the range of aLea JaCta est! normal to the feeling point for a person “sensations” characterizing the human The die is cast! Julius Caesar uttered this of normal hearing. It is undoubtedly the auditory system and arbitrarily defined famous phrase to indicate that crossing best answer to the practical question as each step as a “sensation unit.” the Rubicon was an irrevocable act. to what is the percent hearing loss, and However, Edmund Prince Fowler could is very useful in expressing general From here, it was only a short jump to not have known that placing the 100%- results. It is particularly useful for the concept that the hearing loss of a of-normal-hearing line at the top of the describing to the patient his degree of hearing-impaired person could be audiogram form was a similar irrevocable hearing. However, for an accurate represented as a loss in sensation units; act. expression of the degree of hearing loss, if the normal sensation range, from just- it seems desirable to express results in heard to just-felt, was 6.7 sensation units, Fowler’s influence in the otologic terms of sensation units rather than and the patient’s threshold of audibility community in the decade of the 1920s percent hearing loss.”[p 167]13 was 2.1 units above the normal threshold was so pervasive that no one ventured to of audibility, then one could say that the challenge it; indeed, his colleagues In 1923, Fletcher presented audeograms patient had a loss in sensation units of seemed to applaud the concept. The [sic] of patients with typical deafness in 31% (2.1/6.7). In other words, one could vertical scale satisfied the notion that the which the intensity dimension was
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 33 |
this range too small for making meaningful distinctions among different degrees of hearing loss. In the Western Electric 1-A audiometer, he and Wegel redefined hearing loss as:
HL = 10 log I/Io = 20 log P/Po , where...
I is the patient’s threshold power level, Io is the threshold power level of the average normal ear, P is the patient’s threshold pressure level, and Po is the pressure level of the average normal ear.
They adopted what we now know as the decibel notation, thereby increasing the Figure 5. Fletcher’s graphic scheme: Example of the same hypothetical audiometric contour of a person with a high-frequency loss as shown in Figure 4, but here plotted in the scheme originally advocated by range on the vertical dimension from Harvey Fletcher. Open circles represent “Normal Threshold of Audibility,” filled circles represent “Threshold slightly less than 7 sensation units to of Feeling,” filled squares represent “Audibility thresholds” of the same patient whose percent-of-normal- about 120 decibel (dB) units. As a result hearing results are shown in Figure 4. [Based on Fletcher 1923,12 Figure 2, p 493] of Fletcher’s influence, over the next decade, “sensation units” and “sensation presented in just exactly that fashion. An scale. The audiogram was now doomed to loss” slowly gave way to “Loss in example is shown in Figure 5. The filled be upside-down forever. Decibels.” In a 1943 publication14 by squares reflect the data of the same Implicit in Fowler’s original concept of Fowler’s son, Edmund Prince Fowler Jr, hypothetical contour shown in Figure 4. “sensation units” was the principle that the vertical scale in one of his figures Audiologists who deal with the intensity, or hearing loss, was plotted [Figure 1a, p 393] is clearly labeled frequency-response data of amplification relative to average normal hearing rather “Hearing Loss in Decibels.” devices will recognize how much more than relative to a physical baseline; at easily the response of the impaired ear each frequency, the straight line at 100% Some years later, in a move toward and the response of the hearing aid could on Figure 4 was simply the threshold of terminological purity, Hallowell Davis, at have been compared over the past half- audibility straightened out to eliminate Central Institute for the Deaf in St Louis, century if this representation of the fact that the sound pressure level pointed out that “loss” can only be audiograms had been retained. corresponding to that 100% level varies expressed relative to a known previous with frequency. This concept quickly status of the patient rather than relative Clearly, physicist Fletcher was more took hold, leading to the terminology to average normal hearing. The term comfortable with a purely physical scale “Hearing Loss in Sensation units.” “Hearing Level in dB” (dB HL) was of sound intensity than with the deemed more appropriate for the vertical percentage concept based on the range By 1926, Fletcher was publishing scale. This brings us to contemporary between “just audible” and “just felt.” But audiograms in which the vertical scale usage. when he had convinced Fowler to was “Hearing Loss–Sensation Units.” By abandon the “percent-of-normal- 1928, Fowler had abandoned his And that is the interesting story of how hearing” concept, he failed to follow “Percent of Normal Hearing” measure the audiogram came to be upside down. through on the approach illustrated in and now plotted audiograms with Figure 5. Instead, he renamed Fowler’s intensity progressing downward from 0 refLeCtions vertical scale “sensation units” in which to 120, and labeled “Sensation Loss.” What lessons might we derive from this each unit represented not a percentage saga? First, it seems clear that relating a change but a 10:1 change in sound introduCtion of the patient’s degree of hearing loss to the pressure, but left the zero line at the top deCiBeL notation physical characteristics of amplification rather than moving it to the bottom of In the original conception of the devices would have been greatly the graph. He simply changed the 100% sensation unit, slightly less than 7 units simplified if Fletcher’s scheme for the line at the top of the graph to 0 sensation covered the range from audibility to format of the audiogram (see Figure 5) loss and renumbered so that increasing feeling in the most sensitive portion of had ultimately survived. Both sets of data loss moved downward on the vertical the auditory area. Fletcher13 thought would have been based on the same
34 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | physical reference at all frequencies sound pressure levels above the 1924;23:266–285. rather than the present situation in which audibility threshold, has a certain face 5. Fagen M. A History of Engineering and Science in the Bell System. Vol II, National Service in one is based on sound pressure levels validity. The fact that the usable range of War and Peace (1925-1975). Murray Hill, NJ: that vary across the frequency range hearing varies across the frequency range Bell Telephone Laboratories Inc; 1975. according to the variation in “average is a fundamental property of the auditory 6. Dean L, Bunch C. The use of the pitch range normal hearing” (the audiogram), while system but is not evident from the audiometer in otology. Laryngoscope 1919;29:453. the other is based on the same reference contemporary audiometric display. 7. Bunch C. Auditory acuity after removal of the 2 sound pressure level (0.0002 dynes/cm In any event, two quite sensible ways of entire right cerebral hemisphere. J Am Med or 20 μPa) at all frequencies recording audiometric threshold data Assn 1928;90:2102. (amplification characteristics). emerged in the early 1920s, Edmund 8. Feldmann H. A History of Audiology. Vol 22: Prince Fowler’s scheme, illustrated in Translations of the Beltone Institute for Hearing Research. Chicago: The Beltone Institute for Second, Fowler’s notion of “…amount of Figure 4, and Harvey Fletcher’s scheme, Hearing Research; 1970. retained sensory capacity” as quantified illustrated in Figure 5. Either would 9. Behar A. Sound intensity and sound level. by “percent of normal hearing” may not probably have been better than the Canadian Hearing Report 2012;7:26–27. have been such a bad idea. It had the present system, and would have 10. Fowler E, Wegel R. Audiometric methods and their applications. In: 28th Annual Meeting of virtue that it yielded a number, at each preserved scientific tradition relative to the American Laryngological, Rhinological, and test frequency, easily understandable as a the ordinates of graphs. Otological Society, Washington, DC, May 4-6, percentage rather than a decibel value. It 1922. Omaha, Neb: American Laryngological, also had the property that the numbers aCknoWLedgMents Rhinological, and Otological Society [now Triological Society]; 1922:98–132. on the vertical scale increased, rather The author is grateful for the many 11. Wegel R. Physical examination of hearing and than decreased, from the bottom to the helpful suggestions of Susan Jerger, binaural aids for the deaf. Proc Nat Acad Sci top of the recording form. Michael Stewart, and Richard Wilson. 1922;Wash 8:155–160. 12. Fletcher H. Audiometric measurements and Fletcher’s discomfort with the threshold This article originally appeared in the their uses. Transactions of the College of Physicians of Philadelphia 1923;45:489–501. of feeling as a point of reference may March 2013 edition of The International 13. Fletcher H. New methods and apparatus for have stemmed from the perception that Journal of Audiology,1 and is adapted and testing hearing. Ann Otol, Rhinol & Laryngol “feeling” must be quite variable across reprinted here with permission from the 1926;35:165–180. individuals with and without hearing publisher. CHR thanks IJA Editor-in- 14. Fowler E Jr. Audiogram interpretation and the fitting of hearing aids. Proc Royal Soc Med loss. In fact, however, the variability of chief Ross Roeser and Managing Editor 1943;36:391–402. the threshold of feeling in young adults Jackie Clark for their help in the 15. Martin M. Decibel—the new name for the with normal hearing is less than the preparation and republishing of this Transmission Unit. The Bell System Technical variability of the threshold of audibility.16 article. Journal 1929;8:1–2. 16. Durrant J, Lovrinic J. Bases of Hearing Science. It has the additional property that it is the Baltimore: Williams & Wilkins; 1977. same in persons with varying degrees of referenCes 17. Reger S. The threshold of feeling in the ear in hearing loss, both conductive and 1. Jerger J. Why the audiogram is upside-down. relation to artificial hearing aids. Psych sensorineural, and in persons with total Int J Audiol 2013;52:146–150. Monographs 1933;44:74–94. 2. Fletcher H. Speech & Hearing in deafness.17,18 18. Lierle D, Reger S. Threshold of feeling in the ear Communication. 2nd ed. New York: Van in relation to sound pressure. Arch Otolaryngol Nostrand; 1953. 1936;23:653–664. 3. Wegel R. A study of tinnitus. Arch Otolaryngol Additionally, a measure of loss based on Canadian Hearing Report 2012;8(3):31-35. the range of useful hearing at each 1931;14:158–165. 4. Wegel R, Lane C. The auditory masking of one frequency (range from just audible to pure tone by another and its probable relation felt), rather than the range of all possible to the dynamics of the inner ear. Phys Rev
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 35 | feature Articles from the Final Seminars on Audition
By Marshall Chasin, Editor-in-Chief
or the past 28 years, Seminars on pediatric facilities such as Boys Town in at Western University’s School of FAudition has been one of my Nebraska. Communication Sciences and Disorders favourite hobbies. Joanne Deluzio and – the William A. Cole Scholarship or I began coordinating this one day Previous speakers included EAG Shaw, the Richard C. Seewald Scholarship. conference back in 1986 and we just Edgar Villchur, Mahlon Burkhart, Lu Contributions can still be given to these had our final one earlier this spring – Beck, Ruth Bentler, Ken Berger, Elliott scholarships by contacting Catherine the 28th annual Seminars on Audition. Berger, Rich Tyler, Mead Killion, Dorais-Plesko at [email protected]. The purpose of this seminar was to get William A. Cole, Richard Seewald, clinicians, hearing aid design engineers, Susan Scollie, Steve Armstrong, Michael Below are three of the summaries from and researchers together in one room Valente, and Catherine Palmer, to just this last Seminars on Audition entitled and provide a speaker or speakers that name a few. “Hearing Though the Ages” with will set the milieu for discussion. In contributions from Dr. Susan Scollie, many ways, much of what was learned This last one was the final Seminars on Dr. Jo DeLuzio, and Marilyn Reed. As was during coffee breaks and from the Audition. We did something a little bit you can probably guess from the areas person sitting next to you. Although different this time around. Instead of of specialty of these people, the seminar there are a number of other continuing participants paying a registration fee, I started with young children and ended education opportunities now such as sought assistance from the hearing aid with senior citizens and their unique on-line CEUs, there was something manufacturers in Canada to cover all communication requirements. special about a face-to-face meeting costs. Funds were graciously provided with people who would not normally by: Also found, following the above three cross your paths. All proceeds went to GOLD SPONSORS articles is a transcript from the scholarships either at the University of Bernafon Canada panel/discussion section from the Western Ontario (Seminars on Audition GN Resound fourth Seminars On Audition between scholarship) or the Institute of Oticon Canada Harry Levitt and Edgar Villchur from Biomaterials and Biomedical 1989, who were the speakers for that Engineering at the University of SILVER SPONSORS meeting. Harry Levitt is a retired Toronto (Poul B. Madsen Scholarship). Phonak Canada professor from CUNY in New York and The Seminars on Audition scholarship Siemens Canada is well known for his pioneering work allowed a student in their final year of Widex Canada on digital hearing aids. Edgar Villchur their master’s degree to attend an “extra- Unitron Canada invented multi-band compression and ordinary” facility anywhere in North is the father of the air suspended America. Recipients over the years have Registration was therefore offered free loudspeaker. Previous issues of the gone to the Canadian arctic to see how of charge to the first 100 people who Canadian Hearing Report have had hearing aid evaluations and follow-up registered. The registrants were asked, Founders of Our Profession columns on was performed over a 3000 km distance however, to make a voluntary both of these pioneers. by dog sled, and also to world class contribution to one of two scholarships
36 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION seMinars on audition|
Early Intervention for Children with Hearing loss: An Update for 2013
By Susan Scollie [email protected]
About the Author Dr. Susan Scollie is an associate professor and faculty scholar at the National Centre for Audiology at Western University. Together with colleagues, she develops and supports the DSL Method for hearing aid fitting in adult and children. Her current research focuses on the evaluation of digital signal processing for hearing aids, and early intervention for children with hearing loss. In her classroom teaching, Dr. Scollie focuses on calibration, pediatric audiology, and advanced procedures in amplification
any Canadian provinces are now whom we serve. They have continued to culminating in The Early Hearing Minitiating universal newborn do so, with re-jigging of important UNHS Detection and Intervention Act (EHDI: hearing screening programs (UNHS), details as recommendation updates in 2010) which added an EHDI while others have not yet begun. This 2007.1 Recommendations, however, do requirement to the Public Health Services pattern significantly lags the progress not result in successful UNHS practices Act at the federal level. NCHAM made in the United States, where 100% on the ground, nor do they ensure that continues their important work, with of states have universal newborn hearing legislative support for programs is current efforts aimed at promoting screening programs in place. Why the achieved. These changes have been legislation for improved hearing aid difference? Over the course of my career, largely mediated by the National Centre coverage in health care plans. I have witnessed the transformation of for Hearing Assessment and Management this area of our scope of practice, from (NCHAM), which has worked diligently Do we have parallel efforts in Canada? high-risk registry screening to present to provide nation-wide clinician training Although we can lean upon standards day practices. Interactions with and legislation development for many development (such as ANSI) and colleagues involved in this rapidly years, among other initiatives. evidence from audiology science from changing area has allowed me to observe Remarkably, NCHAM provided proposed south of the border, leaning upon their the impacts of what I feel have been bill “templates” that could be efforts in health care legislation is less major factors in the near-universal downloaded at no cost, and used as a likely to be helpful. Our health care implementation of UNHS south of the starting place for discussions with systems are just too different. It’s border. These include the recommend- legislators, keeping track on a national encouraging that we seem to have a ations of the interdisciplinary Joint map with colours indicating states with recent parallel to JCIH. The Canadian Committee on Infant Hearing (JCIH), versus without legislation. With most of Pediatric Society recently issued a report which recommended UNHS in 1996. the legwork done, advocates for UNHS on Canadian public policy and child and This impactful group includes not only could provide a bill to their elected youth health entitled “Are We Doing those from our profession, but also our representatives that was 99% complete. Enough?”2 Listed third among eleven key colleagues from medicine (especially This single act is likely responsible for the areas for improvement is “Newborn pediatrics), speaking with one evidence- widespread legislation supporting UNHS hearing screening” alongside such based voice for the good of the children in the United States, most recently mainstream issues as youth smoking,
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 37 | child and youth mental health, and monitoring of outcomes in children who First, effective feedback control is of bicycle helmet legislation. Powerful use hearing aids has been a major area of obvious interest for any pediatric fitting, messages supporting the cost-benefit of change in pediatric practice in recent but does it partner well with open fitting early detection of infant hearing loss are years. New tools are available. The for pediatrics? The issue of open fits for provided in this important document, as sections below will review these three kids is trickier than for adults, mainly well as 2011 summary table of the areas. because of ear canal size and hearing loss current status of screening programs with magnitude. Kids often pair ears that are recommended next actions. This type of eLeCtroaCoustiC suCCess too small for vents with losses that are position statement sets the stage for and outCoMes challenging for highly vented (a.k.a. follow up action and lends support to Recent studies in Canada have looked at “open”) fittings. Does this take provincial initiatives to initiate legislative the nature of fit to prescribed DSL targets consideration of venting and open fitting support for new programs. for kids on a normal pediatric audiology off of our mental radar screens? Recent caseload. This work has been led by the data from Johnstone et al. may push us a In discussion of these issues, we can and Network of Pediatric Audiologists of little to put it back on the considerations should remember that UNHS does not Canada.3 The group includes a large list, at least for kids with certain types of imply that intervention and follow up number of clinicians from British losses.6 Consistent with older adult data services are available or equitable. We Columbia, Alberta, Manitoba, Ontario, form,7 Johnstone reports better sound have some provinces that provide fully Quebec, and Nova Scotia. Their localization with open versus closed funded, interdisciplinary services that documented fit to targets across molds for children, and shares halt in early childhood due to coverage hundreds of ears is within 5 dB to the particularly interesting cases of children based on age and others that carry on to limits of the gain of the device. These with unilateral hearing losses. Children age 18. We have others that provide data have been used to develop a who were provided with an open fit in government-funded or low-cost hearing normative range of Speech Intelligibility their aided ear were able to localize aids to all children, and others that rely Index (SII) values for well-fitted hearing sound better: is there a sensitive period upon the limited means of families to aids. In contrast, two recent U.S. studies for spatial hearing development? Recall purchase full-cost hearing aids for have examined children whose hearing that the primary cue for horizontal sound thousands of dollars. A national initiative aid fittings are “off the street” to see how localization is low frequency timing to improve access to equitable health care they fare. Both studies,4,5 found that difference between ears.8 The best way to for infant and childhood hearing although many children were fitted well, preserve and deliver this timing cue is impairment could call not only for a subset of children were not. Stiles et al. through a large vent, if appropriate for UNHS, but also equitable and evidence- found that low versus high SII values the degree of loss. We can verify the based intervention services that take cost were predictive of poor word acoustic transparency of open fittings by burdens into consideration. recognition, phoneme repetition, and comparing the open ear response to the word learning. These results reinforce the occluded ear response with the aid worn Evidence-based intervention with importance of consistent hearing aid but turned off. This can tell us how hearing aids is possibly a more practices, with routine electroacoustic much vent-transmitted sound is making comfortable topic. New evidence and verification and use of a validated its way into the ear canal. These developments in hearing aid fitting prescriptive method. The basics still protocols for verification have not techniques for children offer several matter. changed over the years (it’s just the classic messages: (1) the electroacoustic “REOG” approach9) – what’s different is “success” of the fitting seems to matter, neW teChnoLogies: evidenCe, that it’s now relevant to more of our with new studies of outcome revealing fitting, and verifiCation fittings. that children whose hearing aids are Over the past decade, advances in digital grossly underfit have significantly poorer signal process have allowed us to have Other enhancements in signal processing outcomes than do their well-fitted peers; feedback controls (leading to open fitting include noise reduction and frequency (2) new technologies in hearing aids may more often than ever before), noise lowering. We are motivated to pursue have different uses for kids, and new reduction, and frequency lowering. options for use in noise because children tools for verifying these may be helpful These three technologies can be spend a lot of their day in noise.10 We are in making clinical selection decisions; (3) considered from a pediatric perspective. motivated to pursue options for
38 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | frequency lowering for fittings where experienced dramatic and rapid changes of school-age listening landscapes: Implications extended bandwidth can’t give us access both from the fronts of policy and for pediatric hearing aid fittings. Journal of Educational Audiology 2011;17:23–35. to the important fricative cues in product. This update article highlights 11. Stelmachowicz P, Pittman A, Hoover B, et al. speech.11 Management of loudness in some of these areas, with a discussion of The importance of high-frequency audibility in noisy situations can take the form of their impacts on change in clinical the speech and language development of children with hearing loss. Archives of simply using less gain in those practice. We have wonderful tools for Otolaryngology -- Head & Neck Surgery situations.12 This strategy is implemented hearing aid signal processing, 2004;130(5):556–62. in DSL v5 as a DSL-Noise prescription,12 verification, and fitting. We need better 12. Scollie S, Ching T, Seewald R, et al. Evaluation of the NAL-NL1 and DSL v4.1 prescriptions for and has been shown effective in resources for universally available early children: preference in real world use. maintaining audibility of speech cues detection and cost-effective intervention International Journal of Audiology 2010;49: while reducing loudness for high-level for permanent childhood hearing loss. S49–S63. 13. Crukley J, and Scollie S. Children's speech 13 inputs. A variety of other noise-focused recognition and loudness perception with the signal processors exist, and new referenCes Desired Sensation Level v5 Quiet and Noise verification techniques are available to 1. Joint Committee on Infant Hearing. Year 2007 Prescriptions. American Journal of Audiology position statement: Principles and guidelines for 2012; Doi: 10.1044/1059-0889(2012/12-002). probe their function effectively (For a early hearing detection and intervention 14. Smriga DJ. How to measure and demonstrate review of these, see Smriga, 2004.14). programs. Pediatrics 2007;120:898–921. doi: four key digital hearing aid performance Frequency lowering signal processing is 10.1542/peds.2007-2333 features. Hearing Review 2004;11(11). 2. Canadian Pediatric Society. Are we doing 15. Glista D and Scollie S. Modified verification now available in many different forms: enough? A status report on Canadian public approaches for frequency lowering devices. we use the term “frequency lowering” as policy and child and youth health. ISSN 1913- AudiologyOnline 2009; http://www.audiology- an umbrella which covers frequency 5645. Accessed from: http://www.cps.ca/ online.com/articles/article_detail.asp? advocacy-defense/status-report. 2012. article_id=2301. transposition, compression, and 3. Moodie S, Bagatto M, Miller L, et al. An 16. Glista D, Easwar V, Purcell D, and Scollie S. translation. Each of these provides a Integrated Knowledge Translation Experience: (2012). A Pilot Study on Cortical Auditory different type of frequency lowering Use of the Network of Pediatric Audiologists of Evoked Potentials (CAEPs) in children: Aided Canada to Facilitate the Development of the CAEPs change with frequency compression effect. Outcomes research on the use of University of Western Ontario Pediatric hearing aid technology, International Journal of frequency lowering for children has Audiological Monitoring Protocol (UWO Otolaryngology 2012; Article ID 982894, provided data on efficacy, effectiveness, PedAMP v1.0), Trends in Amplification doi:10.1155/2012/982894. 17. Glista D, Scollie S, and Sulkers J. Perceptual 15 16 2011;15:34–56. and candidacy, acclimatization, sound 4. McCreery R, Bentler R, and Roush P. The acclimatization post nonlinear frequency quality, and changes in brain activity characteristics of hearing aid fittings in infants compression hearing aid fitting in older arising from changes in audibility from and young children. Ear and Hearing 2012; in children. Journal of Speech, Language, and Hearing Research 2012; Doi:10.1044/1092- 17 press. frequency lowering. Case studies reveal 5. Stiles D, Bentler R, and Mcgregor K. The speech 4388(2012/11-0163). the importance of fine tuning to an intelligibility index and the pure-tone average 18. Scollie S and Glista D. (2011). Digital signal appropriate setting for each individual, as predictors of lexical ability in children fit with processing for access to high frequency sounds: hearing aids. Journal of Speech, Language, and implications for children who use hearing aids. in order to achieve actual benefit in Hearing Research, first published online on ENT and Audiology News 2011;20(5):83–87. speech sound detection and January 5, 2012 as doi:10.1044/1092- 19. Glista D and Scollie S. (2012). Development recognition.18 Obtaining these outcomes 4388(2011/10-0264); 2012. and evaluation of an english language measure 6. Johnstone PM, Náb lek AK, and Robertson VS. of detection of word-final plurality markers: The in clinical practice is supported by the Sound localization acuity in children with University of Western Ontario Plurals Test. use of systematic verification and fine unilateral hearing loss who wear a hearing aid American Journal of Audiology 2012;21:76–81. tuning protocols.17,18 We can monitor the in the impaired ear. Journal of the American 20. Ng S, Meston C, Scollie S, and Seewald R. Academy of Audiology 2012;21:522–34. Adaptation of the BKB-SIN test for use as a outcomes for individual children with 7. Noble W, Sinclair S, Byrne D. Improvement in pediatric aided outcome measure. Journal of the targeted tests of speech sound detection aided sound localization with open earmolds: American Academy of Audiology 2011;22:375– aimed at bandwidth and/or frequency observations in people with highfrequency 86. 21. Bagatto M. 20Q: Baby steps following 18,19 hearing loss. Journal of American Academy of lowering effects, as well as more Audiology 1998;9:25–34. verification - outcome evaluation in pediatric generic outcomes monitoring through 8. Macpherson E and Middlebrooks J. Listener hearing aid fitting. AudiologyOnline 2012; caregiver reports or tests of sentence-level weighting of cues for lateral angle: The duplex http://www.audiologyonline.com/articles/ article_detail.asp?article_id=2414). 20,21 theory of sound localization revisited. Journal speech recognition. of the Acoustical Society of America Canadian Hearing Report 2012;8(3):37-39. 2002;111(5):2219–2236. suMMarY 9. Mueller HG. Probe microphone measurements: 20 years of progress. Trends in Amplification The practice area of pediatric audiology 2001;5(2): 35–68. is challenging, important, and has 10. Crukley J, Scollie S, and Parsa, V. An exploration
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My Horsie Has a Cochlear Implant: The Importance of Child-Centred Outcomes for Children with Hearing loss By joanne Deluzio, PhD [email protected]
About the Author Joanne DeLuzio PhD, Audiologist, Reg. CASLPO, is adjunct professor with the Department of Speech-Language Pathology at the University of Toronto.
he “gold standard” for outcomes in important because language learning positive peer interactions will flourish. Tthe field of childhood hearing loss occurs during conversations with The typically hearing children may not is language development and academic adults, and the adults serve as language be responsive to them.1 achievement commensurate with age models for the children. During adult- and cognitive ability. However, child interactions, adults are typically Given the importance of social skills achieving age-appropriate levels in the initiator and they modify their development and positive peer these areas will not necessarily ensure language and communication to interactions, assessment of children that the children have good social- accommodate both the linguistic and with hearing loss should include emotional development (i.e., the ability social needs of the children. measures of social-emotional maturity to form close, confident relationships and peer interaction skills. As well, the and to experience, regulate, and express Peer interactions on the other hand are literature has “reduction of loneliness” emotions within these relationships). also imperative, and may be the as an outcome with children who have Even with good auditory language primary context in which young chronic illness, and these types of measures, the social development of children can practice assertiveness, measures may also be beneficial for many children with hearing loss aggressiveness, and conflict children with hearing loss.4 continues to lag behind their typically management because there is not the Additionally, education for parents hearing peers1,2 power imbalance that occurs when needs to include milestones for social- interacting with adults.3 It is during emotional maturity and social skills Communication training with young peer interactions that children have the development in addition to speech and children with hearing loss relies opportunity to function as equal and language milestones. primarily on adult-child interactions, as autonomous communication partners. the children are usually involved in It may not be sufficient to place Professionals in the field of childhood therapy with one or more adult service children with hearing loss into hearing loss need to move towards providers. Adult-child interactions are integrated classrooms and assume that more child-centered outcomes. This
40 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | means considering outcomes that: are developmental areas including: social- competence. New Haven, CT: Yale University identified by the child, support the emotional development, communication, Press; 2005. 4. Ladd GW, Kochenderfer BJ, and Coleman CC. child’s physical social and psychological language, and academic success. The Friendship quality as a predictor of young development, consider the child’s ultimate goal is for these children to be children’s early school adjustment. Child developmental needs, and measure the healthy and well adjusted and to Development 1996;67:1103–18. 5. Varni J. The PedsQLTM (Pediatric Quality of child’s perceptions of the impact of the experience positive self-esteem, peer Life Inventory). http://www.pedsql.org/; treatments they are receiving. To that acceptance and the ability to form close (2008-2013). end, measures of pediatric quality of life relationships throughout their life. Canadian Hearing Report 2012;8(3):40-41. should be used routinely in the assessment protocol. The pediatric referenCes: quality of life inventory5 (PedsQL) is 1. DeLuzio J and Girolametto L. (2011). Peer interactions of preschool children with and one tool that may be applicable. It without hearing loss. Journal of Speech, addresses dimensions of health that are Language, and Hearing Research of universal concern to children across 2011;54:1197–10. 2. Martin D, Bat-Chava Y, Lalwani A, Waltzman age groups and has data on 35,000 SB. Peer relationships of deaf children with healthy children. cochlear implants: predictors of peer entry The platinum standard in the field of and peer interaction success. Journal of Deaf Studies and Deaf Education 2011;16(1):108– childhood hearing loss should be 20. commensurate achievement in all 3. Ladd GW. Children’s peer relations and social
Third Party Funding: Frequently Asked Questions
Carri johnson, AuD Canadian Academy of Audiology Chair, Third Party Committee
Over the years many of you have sent in longer required to complete NIHB’s federal health partners and requires an questions for the federal health partners. Hearing Aid Confirmation Form. We item that is on their grid, a letter can be Many of these questions are repeated must now only fax the manufacturers written to request an exception. These each year so, I thought I would take this invoice with a copy of the Pre- applications should include the medical opportunity to clarify a few things. authorization Form (referencing their PA reasons why this device is required for number) to their respective Health the clients day to day living. They are did You knoW…… Canada regional office in order to considered on a case by case basis. finalize the approval process VAC will pay for the manufacturer’s If you have questions about any of the invoice cost for earmolds as long as the DND, NIHB, RCMP, VAC have federal health partners please feel free to invoice is submitted with the billing. negotiated 2 year warranties on all contact CAA at anytime of the year. We They will also pay impression fees for hearing aids with all CAEA members. are here to help you and your patients. replacement molds. For ear molds fit This is the standard warranty for all their with the hearing aid originally the cost clients regardless of what warranties you of the impression fee is included in the have negotiated for your private pay dispensing fee. clients
As of June 1, 2013, audiologists are no If your patient is covered by one of the
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When the Brain Gets Hard of Hearing: Paying Attention to Cognition in Hearing Rehabilitation By Marilyn Reed, MSc [email protected]
About the Author Marilyn Reed, MSc, is the practice advisor for audiology at Baycrest, a geriatric care and research center in Toronto, where she has worked since 1997. Marilyn graduated with a master’s degree in audiology from the University of Southampton in England in 1976, and has since worked in clinical audiology in a variety of settings, always with a geriatric interest.
lzheimer’s disease, the most more likely to develop dementia, and the Whatever the mechanism, the evidence Acommon form of dementia, has more severe the hearing loss, the greater strongly suggests that hearing loss may become the primary public health the risk.3 Longitudinal studies have also contribute to or accelerate the concern in Canada. It is the leading cause shown a close correlation between progression of symptoms of cognitive of disability among Canadians over the central auditory processing (CAP) decline in older adults. If management of age of 65, already costs billions of dollars problems and cognitive impairment, hearing loss could reduce or delay the each year, and prevalence is predicted to with scores on dichotic speech tests being progression of dementia, the implications double worldwide within 20 years.1 predictive of the likelihood of cognitive for the cognitive health of older adults Dementia cannot be prevented or cured, decline.4,5 and the costs of dementia to public and there is an urgent need to find ways health and society as a whole are huge. to delay the onset and progression of the The specific mechanisms underlying the disease and reduce the associated social association between audition and Audiologists need to be aware of the and economic costs. cognition are unknown; theories include role that cognition plays in the the possibility of a common cause, due communication problems of our clients Since hearing loss and cognitive to age-related pathological changes in the so that we can begin to apply recent impairment are both highly prevalent in brain, or a causal relationship, with research findings to improve both older adults, dual impairments are hearing loss being a modifiable risk factor assessment and management. While it common. However, hearing loss is more for cognitive decline. Possible causal may be obvious which clients have more prevalent in those with dementia than in pathways might involve the additional advanced dementia, milder cognitive matched control.2 The link between age- burden that hearing loss places on impairment is difficult to recognize in related hearing loss and cognitive declining cognitive resources needed for only one or two visits, and yet can have a impairment has been well-established information processing, or the lack of significant impact on the success of our through over 30 years of research, but cognitively stimulating interaction and interventions. A “snapshot” of the recent epidemiological findings show social isolation resulting from sensory cognitive status of randomly selected that older adults with hearing loss are deprivation. Baycrest audiology patients over the age
42 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | taBLe 1. Modified assessMents for patients With deMentia hearing loss and cognitive decline. We do Give short, simple instructions know that there is a great need to Practice, to ensure instructions are understood provide and improve services for this Provide prompting and encouragement population11,12 for whom amplification Accept a variety of responses in the form of hearing aids provides Get most valuable information first (i.e. minimize fatigue, agitation) limited benefit and poses problems for Speech testing (meaningful stimuli) more successful that PTs; SRTs more reliable management. Our current, technology than PTTs focused approach is not very successful Obtain SATs where SRTs unobtainable for older listeners and needs to be Use any speech material that is effective; meaningful/familiar speech (simple resituated in a broader context of questions or digits more successful than PBs or spondees) audiologic rehabilitation (AR) because of Test at time of day when most alert (usually morning) the important role that training and Presence of caregiver/family member may reduce agitation or anxiety therapy play in promoting compensatory Assess over multiple sessions if needed cognitive function.13 Include speech in noise and CAP test (s) appropriate to capability, if possible Objective assessment; acoustic reflexes, ABR (OAEs unlikely) Speech perception difficulties of the elderly result from a complex interaction of 68 years revealed that 16 out of 20 that address the impact of cognitive of sensory and cognitive processes, and failed the Montreal Cognitive Assessment decline on patients’ ability to provide arise from peripheral, central and test, indicating that they had at least mild information and the most effective ways cognitive changes that occur with age. cognitive impairment and suggesting that for us to obtain it. We should also Listening, comprehending and cognitive screening is warranted. Many include new tests that provide communicating require more general authors advise us that this is indeed the information about higher auditory and cognitive operations such as attention, case.6–8 Assessment of cognitive status cognitive processing; we need to do more memory, and language representation.14 through observation of behaviour, than speech testing in quiet to get In daily life, listeners constantly take in history taking, screening tools, or speech information about the entire auditory bottom-up information using their tests that address working memory and system that will assist with management hearing, and combine it with “top-down” other aspects of auditory processing and decisions. Specialized speech tests can knowledge that’s learned and stored in cognitive function would be a valuable provide much information about the brain. The more difficult the listening addition to the audiologic assessment functional communication ability, CAP conditions, the more effort we have to battery. Similarly, assessment of hearing and aspects of cognitive function, and are make to hear and understand. This should be part of any assessment of available in varying degrees of difficulty increased listening effort puts more cognitive function, especially since many to suit the ability of the patient. Dichotic demands on cognitive resources needed cognitive tests are verbal and therefore tests which target binaural integration for other aspects of information impacted by hearing loss. Audiologists skills, dual tasking and memory target processing such as deriving meaning and can play an important role in the both auditory and cognitive processing. storing in memory. Cognitive decline education of other health care The dichotic digit test9 is recommended makes it harder for older listeners to professionals in this area, and provide by many in the literature10 as being the ignore, inhibit or suppress irrelevant them with hearing screening tools and most appropriate and cost-effective for acoustic stimuli like music or competing referral criteria. use with the elderly, and is currently voices, and attend to the specific voice of under trial in our clinic at Baycrest. interest. Poorer working memory (WM) There are currently no established best makes it harder to fill in the gaps in practice protocols for the audiologic How does knowledge of cognitive status conversation, and the effort of listening assessment of patients with cognitive change what we do? Baycrest and paying attention means that older impairment. While those of us working audiologists are currently looking at listeners are less likely to understand and with elderly clients have developed our whether we modify our services based on remember what they’re hearing, even if own modifications to test procedures awareness of our patients’ cognition, with they hear it.15 Focusing on the hearing (see Table 1), it would be helpful to a view to developing and integrating best aid as a “fix” for their communication develop more standardized test protocols practice procedures for those with both problems misleads many clients with
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 43 | taBLe 2. Considerations for fitting for persons With age- age-related hearing loss into having reLated Cognitive and phYsiCaL iMpairMents unrealistic expectations and sets them up Automated features, minimal manual controls for failure. No matter how perfect our Verbal prompts real-ear aided responses are, the speech Manageable battery doors (marked if low vision) signal provided at the periphery will be Removal cords distorted by damaged central and Safety loops for attachment to clothing for advanced CI cognitive processing.8,16 For previous users: do not change style (or manufacturer) of aid Hearing aids can both help and hinder do not change battery size or style of door success with communication; they can reduce listening effort by improving the Facilitate phone use with hearing aid, so not removed quality of the signal reaching the Establish routine for storage once removed auditory cortex through restoring Remote controls intuitive/user friendly audibility and improving the signal to Accessories to improve SNR (remote microphone, FM compatible) noise ratio with directional longer acclimatization period (6–12 months) microphones and noise reduction Written instructions (large print, pictures, supported communication) algorithms. However, complex signal Schedule prompt and more frequent return visits processing may not necessarily be Counseling and AR; group/social model beneficial for everyone, as it may Involve/instruct caregivers in management and AR introduce distortions in ways that impede or cancel the intended benefits taBLe 3. ar strategies to iMprove CoMMuniCation in oLder for some individuals. Studies show that aduLts those with cognitive impairment and Bottom-up strategies lower WM are more susceptible to Management distortion from fast amplitude Use of assistive technology compression (WDRC) and frequency Requesting Clear Speech (slow rate, etc.) compression/lowering and that HA Use of visual cues (speech reading and graphics) signal processing should be less Environmental modification and manipulation aggressive for these patients.16–18 Binaural aiding may not be the best therapy strategy for some elderly persons for Auditory skills training such as difference between /ba/ and /da/ whom higher auditory processing “Communication exercise”: adaptive, repetitive, practice such as. listening and factors such as decreased inter- Communication Enhancement (lACE21) using neuroplasticity to change neural hemispheric communication and responses to sound binaural integration result in reduced ability to use binaural cues.19,20 Aging top-down strategies and cognitive decline also appear to Management affect hemispheric asymmetry in Teaching communication partners (caregivers, etc) importance of clear language (plain, linguistic processing, so that asymmetry familiar language; short, simple sentences) favoring the left hemisphere reverses, Use of context resulting in significant right ear Giving more time to process advantage in those with cognitive impairment.10 therapy Teaching compensatory strategies (active listening; communication repair; self-efficacy; Of course we also have to pay attention self-advocacy) to non-acoustic factors related to age- Stress reduction exercises (reduce anxiety and confusion) related cognitive and physical limitations Auditory and cognitive training to improve working memory (Table 2). Include caregivers in communication training
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If our goal is to maximize our patients’ project that will follow older adults over people with dementia presents unique ability to communicate, we must consider time to see if audiologic interventions will challenges. The Hearing Journal 2009;62(11):39–43. the role of cognitive processing in AR. It help delay the onset or slow the 13. Pichora-Fuller MK. Perceptual effort and is impossible to disentangle sensory loss progression of cognitive decline. At apparent cognitive decline: Implications for from cognitive processing in older Baycrest, audiologists will be working audiologic rehabilitation. Seminars in Hearing 2006;27:4. listeners, and so effective intervention with psychologists to look at whether 14. Kiessling J, Pichora-Fuller MK, Gatehouse S, et must include both amplification (bottom- fitting HAs and providing AR will have a al. Candidature for and delivery of audiological up) and training (top-down) to improve positive impact for patients with early services: Special needs of older people. International Journal of Audiology auditory skills and teach compensatory dementia and their caregivers. If this is 2003;42(Suppl 2):2S92–101. behavioral strategies. Bottom-up strategies indeed the case, the implications are huge, 15. Pichora-Fuller MK. Audition and cognition: focus on access to a clear signal, while top- and audiologists could play a critical role Where the lab meets clinic. ASHA Leader 2008;13(10):14–17. down strategies focus on functional in providing solutions to this pressing 16. Humes LE. Modeling and predicting hearing- communication (see Table 3, based on public health concern. aid outcome. Trends in Amplification Ferre, J: Rehabilitation for Auditory 2003;7(2):41–75. 17. Gatehouse S, Naylor G, and Elberling C. Linear Processing Difficulties in Adults, ASHA referenCes and non-linear hearing aid fittings – 2. Patterns on-line seminar, 2012). 1. Alzheimer’s Society of Canada. Rising tide: the of candidature. International Journal of impact of dementia on Canadian society. Audiology 2006;45:153–71. Toronto: Author; 2010. 18. Lunner T and Sundewall-Thorén E. Interactions “There’s more than one way to recognize 2. Uhlmann RF, Larson EB, Rees TS, et al. between cognition, compression, and listening a word”13; through AR techniques, we can Koepsell. Relationship of hearing impairment to conditions: Effects on speech-in-noise teach compensatory behavioral commun- dementia and cognitive dysfunction in older performance in a two-channel hearing aid. adults. .Journal of the American Medical Journal of the American Academy of Audiology ication strategies to patients and Association 1989;261:1916–19. 2007;18:604–17. caregivers, to improve top down 3. Lin FR. Hearing loss and cognition among older 19. Walden TC and Walden BE. Unilateral versus processing and help to compensate for adults in the United States.Journals of bilateral amplification for adults with impaired Gerontology A: Biological Sciences and Medical hearing. Journal of the American Academy of sensory deficits. Sciences 2011;66:1131–36. Audiology 2005;16(8):574–84. 4. Gates GA, Beiser A, Rees TS, et al. Central 20. Kobler S, Lindblad AC, Olofsson A, and Group AR programs not only help older auditory dysfunction may precede the onset of Hagerman B. Successful and unsuccessful users clinical dementia in people with probable of bilateral amplification: differences and adults become more effective Alzheimer’s disease. Journal of the American similarities in binaural performance. communicators, they also foster their Geriatrics Society 2002;50:482–88. International Journal of Audiology participation and social interaction.22 A 5. Gates GA, Anderson ML, McCurry SM, et al. 2010;49(9):613–27. Central auditory dysfunction is a harbinger of 21. Sweetow RW, Sabes JH. The need for and group gives an opportunity for repetitive Alzheimer’s dementia. Archives of development of an adaptive Listening and practice of communication repair Otolaryngology-Head and Neck Surgery Communication Enhancement (LACE) strategies in a meaningful context while 2011;137:390–95. Program. Journal of the American Academy of 6. Kricos P. Audiologic management of older Audiology 2006;17(8):538–58. addressing social participation needs. adults with hearing loss and compromised 22. Worrall L and Hickson L. Communication Social interaction is known to promote cognitive/psychoacoustic auditory processing disability in aging: From prevention to cognitive health and has been shown to capabilities. Trends in Amplification intervention. Clifton Park, NY: Delmar 2006;10(1):1–28. Learning; 2003. have a protective effect against 7. Pichora-Fuller MK. Effects of age on auditory 23. Fratiglioni L, Paillard-Borg S, Winblad B. An dementia.5,23,24 The Hard of Hearing Club and cognitive processing: implications for active and socially integrated lifestyle in late life at Baycrest was designed for seniors with hearing aid fitting and audiologic rehabilitation, might protect against dementia. Lancet Neurol Trends in Amplification 2006;10(1) 29–59. 2004;3(6):343–53. severe hearing loss at risk for social 8. Lunner T. Memory systems in relation to 24. Hultsch DF, Hertzog C, Small BJ, and Dixon RA. isolation and has successfully addressed hearing aid use. Cognition, Audition and (1999). Use it or lose it: Engaged lifestyle as a both educational and social needs for Amplification, AAA Conference, Boston; 2012. buffer of cognitive decline in aging? Psychology 9. Musiek F. Assessment of central auditory and Aging 1999;14:245–63. many of its members over the 13 years dysfunction: The Dichotic Digit Test revisited. 25. Reed M. The Hard of Hearing Club: A social that it has been running.25 Ear and Hearing 1983;4:79–83. framework for audiologic rehabilitation for 10. Idrizbegovic E, Hederstierna C, Dahlquist M, et seniors with severe hearing difficulties. In L. al.Central auditory function in early Alzheimer's Hickson (Ed), Hearing care for adults: The There is a pressing need for audiologists disease and in mild cognitive impairment.Age challenge of aging. Phonak: Stäfa, Switzerland; to understand how cognitive impairment and Ageing 2011;40:249–54. 2009 interacts with hearing loss so interventions 11. Lin FR, Metter EJ, O’Brien RJ, et al. Hearing loss Canadian Hearing Report 2012;8(3):42-45. and incident dementia.Archives of Neurology can be tailored to better suit client needs. 2011;68:214–20. Dr. Lin is conducting another research 12. Kricos P. Providing hearing rehabilitation to
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 45 | paneL disCussion froM the 4th seMinars on audition
Signal Processing Techniques in Hearing Aids Fourth Annual Seminars on Audition February 25, 1989 (Toronto)
Co-ordinator: Marshall Chasin, AuD., Reg. CASLPO (far left) Speaker: Harry Levitt, PhD, City University of New York (middle) Speaker: Edgar Villchur, MS Ed., Foundation for Hearing Aid Research (left)
Question: Could you please give some stress, such as the lengthening of the effect only affecting the fricatives. I don’t information on the redundancy of stressed syllable, the intensity of the know of any application of this in any speech? voiced syllable, and the increasing of the hearing aid. voice pitch of the stressed syllable. All of E. Villchur: The consonants are these cues depend on the stress, and that H. Levitt: There have been a number of identified not only by their spectral is a redundant situation. If only one of experimental devices along these lines, makeup, but also by their temporal those cues is heard, such as may be the but I’m not familiar with any one of them pattern. A [t] starts out with a sharp jump case with a hearing impaired person, which has reached the marketplace other in amplitude and tapers off. Also, the then the redundancy is reduced so that than the Johanssen device. consonant is affected by the vowel the meaning may not be apparent. environment – it is preceded or followed E. Villchur: One problem with these by one sound or another. If interference Question: What are your experiences devices is that you have to learn a new destroys on or two of these cues, the third with frequency displacing hearing aids language. You have to learn to recognize one may be enough to identify it. One of which transpose the high frequencies new sounds. The thing I liked about the the cues that allows us to understand and impose them on the lower? synthetic fricatives, which followed speech is the context or meaning of the surrogate fricatives (Levitt), is that you speech. If I say “I fell out of the boak,” we E. Villchur: Work by Johanssen, in don’t have to learn a new language. are going to change that [k] to a [t], Sweden, has tried to do this, and indeed because it doesn’t make sense otherwise. they came out with a commercial H. Levitt: These transposition devices But if I also miss the [b] or the [o], I won’t product (under the name of Oticon in the can be broken up into three groups (1) have the additional cue. 1970s). There was a modification of this which transposes everything from the which was published in an IEEE journal high frequencies to lower ones, (which H. Levitt: Another example of within the last decade, where instead of have not been particularly successful), (2) redundancy is to stress a syllable. In the folding the entire high frequency band the phonetic transposition devices which word “confuse” – we change the stress onto the low frequency band where they first decides whether it’s a fricative or pattern and the meaning is changed. feared interference effects, he only folded another sound, and only that sound is There are cues that are correlated with the energy above 5000 Hz back down, in transposed down, (and that reduces the
46 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | distortion and the transposition only is intelligible in an 800 Hz band because most prevalent distortions which affect occurs during fricatives. This has been unprocessed normal speech cut off above the hearing impaired are (1) attenuated more successful and the model was 800 Hz is intelligible. The question is frequency response and (2) recruitment. published around 1968), and (3) logic whether intelligibility is improved with a If you make this assumption then data frequency transposition which is a device hard of hearing person. When you will be presented via the amplitude which reduces everything only slightly so compress the frequencies of speech range. All that the dual channel that speech still sounds like speech. We down to 800 Hz, one of the things you compressors are, are two little men get small improvements in intelligibility do is bring the frequency components of turning volume control wheels up or particularly with female and children’s speech much closer together. When a down – nothing more mysterious than voices which have a higher pitched person cuts of at 800 Hz, that person is that. Even if you solve the above frequency spectrum. If you transpose likely to be in the profoundly deaf group mentioned two major distortions, you about 20% down, you are likely to and is likely to suffer from problems in don’t restore normal hearing, which improve intelligibility. frequency resolution. It may be that implies that there are other aberrations, bringing those formants together may do which either can or cannot be Question: Dan Graupe who invented more harm than bringing the high compensated. All I can do is discuss the the Zeta Blocker chip, has stated that frequency elements down to within the ones we know about and they are in he has a system which can reduce 800 Hz range. terms of amplitude. speech down to an 800 Hz bandwidth and still be intelligible, because he Question: When you have a profound Question: The kind of dimension that was us ing a non-linear frequency loss which requires a high amount of is missing is the temporal one. There transposition instead of a linear one. gain but at the same time you have are experimental data which go back recruitment, how do you make the quite some time which show that even H. Levitt: Non-linear transposition has compromise between the gain and the if two people have identical amplitude been tried at MIT and they call it saturation level of the hearing aid? audiograms, one may have very good frequency warping. To my knowledge speech understanding and the other, they have not gotten particularly exciting E. Villchur: The best you can do is to poor. The studies have tried to results. But, they also did a feasibility amplify speech to within these limits but determine what other variables can study which was quite interesting. One the first thing you need to do is to make explain the differences between these of the arguments against radical these sounds audible by giving extra two individuals. Of all the variables frequency transposition is that the amplification to the weak sounds to looked at, temporal resolution was the resulting speech is not recognizable bring them into the residual dynamic most likely candidate. The one with without training. You have to learn a new range of the subject, without over better temporal resolution also has code. There is a fundamental question amplifying the intense sounds. This may better speech understanding. This whether you can actually learn the new not be enough but at least this is the first implies that we not only need to code. The group at MIT created artificial thing that must be done. If you decide measure the amplitude/recruitment speech sounds which were all under that you are going to use some other type characteristics of an individual, but we 1000 Hz and that were as perceptually of processing, it’s important not to drop need to measure the temporal different from each other as possible. that processing which at least made the resolution characteristics as well. It’s These were clicks and all sorts of strange sound audible. not an easy thing to do but it can be sounds. They trained people to associate done, and I think that we should pay these sounds with speech sounds. They Question: In all of the examples today, more attention to it. Hopefully that were able to demonstrate that it was the hearing impaired person was will indicate what methods of signal possible to at least train a person to learn described through the audiogram and processing will be required in the the consonant set. So in principle, people the intensity dynamic range. Do you temporal domain to improve hearing. could learn a new code. Nobody has yet see any alternatives to describing the come up with a machine which does it hearing impaired by other means? E. Villchur: You can’t have temporal automatically. resolution for sounds that you can’t hear. E. Villchur: The presentation was based Therefore, first bring the sound into the E. Villchur: I have no doubt that speech on an assumption which is that the two dynamic range of the hearing. It’s a
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 47 | necessary, but possibly insufficient restoring some cues which are transformation worked quite well. condition for achieving what we want. insufficient for intelligibility (accent, stress), gives them an advantage for lip Question: Dr. Levitt mentioned that it Question: One of the problems with reading. In some cases you just have to was important to maintain the phase multi-band compression is that it give up. characteristics of the speech in the seems to interfere with temporal digital processing system. Would that characteristics. Do you have a Question: When you map the high be related to temporal information or comment? frequency information into the low something else? frequency region, are you not E. Villchur: There is no question that destroying the temporal cues by doing H. Levitt: Basically phase information is compression reduces temporal this? In this case would you not be temporal. There are some conflicting resolution. It has to. For example, if you better to present both low and high data in the literature, which I’ll remind have two sounds, one following the frequency artificial cues rather than you of. A lot of data show that when you other, and the first sound drops off and overloading the low frequency band? discard phase information in speech such then there’s silence, and then the next as on the telephone, the speech remains sound starts, the time where the first E. Villchur: That has been done by using intelligible and that you can hardly tell sound is dropping off will be changed by a vocoder system where a few individual the difference. That is true for any the compression – it will be lifted. The bars of noise have been modulated to monaural listening system. On the other faint, trailing parts of the first sound will represent speech and from that way of hand, there are substantial data which be increased by the compression. The thinking, I prefer to use my synthetic show that if you have a binaural listening compression will tend to fill in the gap fricatives which only interferes at one system, phase information is greatly between the two sounds. What it will do point over a third of an octave at the top important. So we have two rather is to restore the temporal resolution to of the residual range, rather than folding extreme sets of data – monaural (phase that of a normal listener. The person over the entire frequency spectrum. As unimportant) versus binaural (phase before compression hears a more for the vocoder system, it’s amazing how important). When people looked into precipitous drop off because of his little you need to present before the noise reduction for monaural systems, recruitment, than the normal listener. system becomes intelligible. I have since these systems used a single But it may be that in some cases, the hard listened to a system with only three bars headphone, it was thought that phase of hearing listener cannot take the of noise going up and down and get an was not important. However, the relative restoration to normal temporal occasional word out of it. By the time you phase between the speech components resolution. It may turn out that he needs get to five bars of noise you understand and the noise components turns out to an abnormally good temporal resolution. it fairly well. be important. The auditory system does But, only to the extent that a properly not discard phase information. Although adjusted compression system interferes Question: Would it not be better to experiments show that phase with temporal resolution, and not by present the high frequency energy in information is not important for restoring normal temporal resolution. the low frequency band only when it understanding speech, it does not mean was important, and to present the low that the auditory system discards phase Question: Some cases of profound frequency energy in the low frequency information. What experiments do show hearing loss do not show any ability band when that was important? is that as part of a noise reduction system, to function on cues that are below 800 even monaurally, if phase information is Hz. I am questioning whether the H. Levitt: That is indeed the philosophy retained, we get better results. transposition of cues to the low underlying the technique of surrogate frequency band would be effective, fricatives. If you had a voiceless fricative Question: In the two channel system and also whether we are using the the low frequency energy is relatively discussed in your talk, where was the same definition of profound loss. unimportant. The only energy that crossover between the low and the counts is the high frequency energy. With high frequency channels? E. Villchur: There are some profoundly the exception of these voiceless fricatives, deaf where there is no way to restore the low frequency sounds are more E. Villchur: In the tapes that I played, I intelligibility. It has been shown that important. That particular form of used the average compensation
48 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION | characteristics required by the six was to place the speech band in the same impaired people have in a noisy subjects that I used in my 1973 study, position between his threshold and the environment. One is to try to optimize which was 1500 Hz. But the last tape equal loudness contour, as that for a the conditions which they listen in that that I played through the Resound normal hearing person. The average for environment so that the target signal has hearing aid has an adjustable crossover the entire band was about 3:1 (frequency a better ratio to the background signal. between 800 Hz to 2000 Hz. Among the by frequency), and the subjects did not The other thing is to ignore the signal to six subjects there was a variation of no like it. They reported that speech was ratio and to concentrate on the clarity of more than 1.5:1. The average falls in the strident. I hypothesized that when the the target signal. By increasing the area of 1500 Hz. dynamic range was very severely number of redundancy cues, you make reduced, that other things were going on it possible for the hard of hearing person Question: it appears that the low which meant that they couldn’t take the to operate better within the noisy frequency band in a two channel sound. environment, and that is what I have compression system requires a been trying to do. compression ratio of 2.3 whereas the Question: So can we say that the higher frequency band requires a highest ratio we need is 3:1? Question: Was the recruitment much higher ratio, perhaps even simulator used in your experiments infinite. Is this indeed the case and E. Villchur: In my experience, below a digital or analog? what ratio characteristics would be profound or very severe loss, we would required to cover the hearing impaired not need a ratio in excess of 3:1. A E. Villchur: The one that I published population? profoundly deaf person may need a 5:1 about was done at MIT and I used their ratio. When you get to a compression hybrid system but the one I have at E. Villchur: The compression ratios that ratio of 5:1, it doesn’t make much home, which is the 16 channel one, built I used were not a matter of guesswork or difference. The result is the same as 10:1 by Mead Killion about 15 years ago, is my own hypothesis, but were calculated and so on. With a ratio of 5:1, with an analog. on the basis of a formula which may not input increase of 10 dB, the change in have been the correct one. The formula output will only be 2 dB. If we double Question: Given the equipment which was this; I defined the normal dynamic that to a 10:1 ratio the output change will is out there, how does one go about range at any frequency as the distance only be 1 dB. evaluating level dependent type between threshold and the equal hearing aids? loudness contour pegged to the Question: With your dual channel maximum speech level of conversational system, when you go to a noisy party, E. Villchur: The first who wrote about speech. This is on the order of 65–70 dB the response in noise tends to become level dependent hearing aids is Margo across the spectrum. I then defined the flat. This is in contrast to the Zeta Skinner and she showed that the optimal residual dynamic range of a hearing Noise Blocker, or other ASP system frequency response of her subjects impaired person as the distance between which tries to achieve a relative high depended on level. The lower the level, his threshold and the equal loudness frequency emphasis. Would you the more high frequency emphasis she contour pegged to his preferred listening comment on that? could take. In the higher level, the less level of conversational speech. When you high frequency emphasis was optimum do that, a typical person with E. Villchur: In fact, the frequency for them or indeed that they would moderately-severe to severe impairment, response which I adjusted it to was up 9 tolerate. She came to the conclusion that which my six subjects had, is likely to db at 4000 Hz so it wasn’t flat. I was what was needed was a level dependent require a compression ratio of 2:1 in the trying to see with my experience with frequency response. I wrote her in low frequency band (which represents compressed sound what would happen agreement and said that a level the ratio of the normal dynamic range in a real life situation. It was not adjusted dependent frequency response was the and his residual dynamic range) and a to an optimum setting to my hearing. It same as a frequency dependent ratio of 3:1 in the high frequency band. was purposefully exaggerated. But this amplitude response, which is what you An infinite compression ratio may still be highlights the last thing I was talking get from a dual channel compression intelligible but it accomplishes about. There are two things that you can hearing aid with different compression something new. What I was trying to do do about the difficulty that hearing ratios for the low and high frequency
REVUE CANADIENNE D’AUDITION | CANADIAN HEARING REPORT 49 | bands. I ran a series of curves with my 2 committee which will allow you to use a those discussed here. channel compressor using ratios of 2:1 complex stimulus and to define the and 3:1 showing that at low levels it had characteristics of that spectrum as speech E. Villchur: Neither Dr. Levitt nor I are a contradiction between level dependent spectrum noise. The analysis means will clinicians. The models discussed here frequency response and frequency be a swept spectral analysis at the output have not as yet been implemented in dependent amplitude response, but that or a digital technique. There is some commercial hearing aids. 3M is just they are indeed the same. On the other likelihood that that standard will come coming out. The Resound aid will be out hand, a level dependent frequency through in the next couple of years. in the spring of 1989, but I’m not quite response can be achieved in another way sure. which Mead Killion is currently working Question: In the cochlear implants on using a single channel compressor mentioned today, what are the factors H. Levitt: Regarding the Zeta Noise which he feels will be useful for mild to that limit the frequency of Blocker and similar hearing aids, there is moderate deficits. Mead feels that a 2 stimulation? generally not good clinical follow-up, so channel approach is not needed for these we only have information on those who more mild losses. H. Levitt: You first have to characterize are dissatisfied and that is not the best the implant. There is a single channel way to measure the degree of satisfaction. Question: The current calibration implant with a single electrode, and there However, even using that crude measure, method for evaluating hearing aids are two multi-electrode cochlear and by published return rates, there have uses a swept signal across the implants. One multi-electrode system is been a fair amount of returns of the Zeta frequency range, but this would not be like a vocoder where you have several Nose Blocker. We should have more useful for dual channel systems. contiguous frequency bands and each formal success/failure information on band drives a pair of electrodes. The these systems. H. Levitt: What is needed is a new second type has an array of 22 electrodes standard which would specify the and each one electrode plus a round E. Villchur: I would like to say a word calibration and evaluation of these level electrode is stimulated. You don’t have about the ASP system. One of the two dependent hearing aids. There are several much frequency resolution with the that Dr. Levitt described used a methods being proposed. One method is single channel cochlear implant, and that compressor in the low channel to reduce to use a broadband signal and then implant is on the way out. The multi- the noise and nothing in the high analyze the resultant spectrum. The channel cochlear implant is the one that frequency channel. The compressor will other is to have at least two tones – one allows for coding of frequency reduce the noise only if the compression to get the compressor working and the information in various ways. There are threshold is engaged by noise which is other to sweep across the frequency two essential types of implants. One type intense enough, so this would imply that range. (Editor’s note: A problem can of cochlear implant is a multi-channel it is not a compressor, but actually a occur if the first tone to get the system where there is a correspondence compressor-limiter. With real compressor working is too low in to different frequency bands. The design compressors, weak sounds are not frequency [e.g., 300 Hz], then difference considerations are what frequency range reduced but are increased in gain. Once tones can erroneously enter the bandwidths are required to encode you look at a compressor as increasing frequency response). speech. The other type of implant is weak sounds out of the mud, and once where you extract the features of speech you look at compressor-limiters as E. Villchur: The most common is to use such as the voice fundamentals and decreasing overly intense sounds, it a family of curves – each one at a encode that. This stimulates the becomes important to point out that I successively higher level. Instead of using electrodes in the cochlea. The question is have been talking about compressors and one frequency response curve you will which characteristics of speech ought to not compressor-limiters. That is, a use a series, perhaps spaced every 10 dB be encoded. compressor increases gain, not decreases from 50 to 80 dB input. it. So the Zeta Noise Blocker is more of a Question: For the benefit of those who compressor limiter. Comment: You can’t characterize a non- do not fit hearing aids, could you Canadian Hearing Report 2012;8(3):46-50. linear system with a swept sinusold and comment on the relative effectiveness there is a proposal before the ANSI of hearing aids, including some of
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