We would like to express our sincere thanks to Starkey Laboratories Canada for their generous support in making this supplement possible. |

I know that I may be accused of being a nerd, but I actually have Robyn Cox’s 2005 article on evidence-based practice on my bed side table, and I don’t read it in order to fall asleep. Well, maybe I am a bit of a nerd, but Dr. Cox’s work is seminal to this field and should permeate any clinical program.

Evidence-based research and evidence-based practice means that it is the clinician who must have be the arbiter of what has been demonstrated in the literature to be useful and what may only be marketing. Often, a great sounding idea is just that, but unless it has independent object support that is free from confounding factors, clinical caution must be exercised.

This is a supplementary issue of the Canadian Hearing Report that has been sponsored by Starkey Laboratories. Starkey, like many other manufacturers, has placed a lot of time, money, and effort into ensuring that any innovation is well supported by the literature and this issue is a selection of some interesting well-supported, technologies and ideas.

Dr. Tim Trine is the guest editor for this supplementary issue and he brings with him a wealth of knowledge, both from the clinical and the manufacturing arenas. Under the guidance of Dr. Trine, some fascinating articles are in this issue, led off with a clear statement of the issue at hand, by Dr. Catherine Palmer. This is followed by articles on the prevention of moisture contamination (Dr. Weili Lin), and a novel method for the verification of a hearing aid prescription (Dr. Jason Galster and Dr. Elizabeth Galster). Finally where would an issue on evidence-based practice be without input from Dr. Brent Edwards, who probably knows more about Canada than anyone else I have ever met (except for our current prime minister, the right honourable Jack Harper).

Together this issue stands alone as a reasoned and informative issue that is a must to read and would be quite useful as a supplement to any university course on evidence-based research or clinical practice.

Marshall Chasin, AuD., Reg. CASLPO, Aud(C), Editor-in-Chief Canadian Hearing Report

Reference: Cox, R. (2005). Evidence-based practice in provision of amplification. Journal of the American Academy of Audiology, 16: 419-438.

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It’s a privilege to bring you this special issue of Canadian Hearing Report. Because an evidence-based approach has been the singular foundation of Starkey’s research and development approach over the past dozen years, I thought it would be useful to provide a sample of the diversity of our on-going efforts to establish a strong basis for the product decisions we make. Most readers will be familiar with the strong evidence base we have established for our best-in-class features such as adaptive feedback cancellation, directional processing, and noise performance because our marketing department does an excellent job of keeping that data visible and the details accessible – just take a peek at StarkeyEvidence.com if you’re in doubt. Perhaps not quite as visible but certainly as important, however, are the efforts across many disciplines taken to ensure that every critical aspect of our design is validated and well-supported by evidence. So, following Dr. Palmer’s excellent introduction to the concept of evidence-based practice and the roles and responsibilities therein, we have included three topics that represent a cross-sectional sampling of our approach – from device quality, to clinical utility, to hypothesis-driven research. It might seem axiomatic that medical device product development would be founded on an evidence based approach; however, I think most clinicians will admit that it doesn’t take long to find examples of features that have been over sold or for which evidence simply doesn’t exist. Ironically, it is frequently the case that the features that have the least-proven efficacy are the features that are most often requested by customers. Single- or multi-channel adaptive directionality illustrates this point perfectly. Although most hearing aid companies have embraced this feature and have marketed it aggressively for several years, there is yet to be a single publication in the peer-reviewed literature or in trade journals demonstrating the efficacy of such processing (see Bentler 2005 for a meta-analysis) in anything other than contrived laboratory environments and these contrivances don’t represent the acoustics of everyday life (Woods and Trine 2004). The likely explanation for this demand is threefold:

1. The adaptive directional story fits with our intuition despite the reality of everyday life acoustics; that is, it’s easy to imagine that noises we can localize might be attenuated more if we aim a directional null at them. 2. Adaptive directional systems don’t perform substantially poorer than a directional system that has a fixed pattern. 3. The story is easy to sell to patients; that is, the same intuition that clinicians have can easily be passed along to the patient.

As Dr. Palmer points out in this issue, however, “evidence-based practice is a team effort.” If we truly want to support evidence-based practice, then our approach to product development must not only be dependent upon including those features that have proven efficacy but must also depend on the exclusion of features for which evidence does not exist. This also, of course, puts a burden on the clinician to keep abreast of the literature and to demand the data from manufacturers proving the efficacy of our designs.

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As I was preparing for this special issue, I returned to an article I co-authored several years ago (Trine and Van Tasell, 2002) and I believe the closing words we used then, still apply: “… hearing professionals should expect from manufacturers:

1. hearing aid design that is based on established scientific evidence of effectiveness 2. accurate and honest portrayal of the benefits of new technology 3. flexible fitting systems that will acknowledge potential differences among users in their desire for advanced features, and that will assist hearing professionals to achieve the best possible fit of advanced products to their customers.

I hope you enjoy the issue!

Timothy D. Trine, PhD Chief Technical Officer Starkey Laboratories, Inc.

Bibliography Bentler RA. Effectiveness of Directional Microphones and Noise Reduction Schemes in Hearing Aids: A Systematic Review of the Evidence. JAAA 2005;16:473–85. Trine TD and Van Tasell DJ. Digital Hearing Aid Design: Fact vs. Fantasy. The Hearing Journal 2002;55(2):36–42. Woods WS and Trine TD. Limitations of Theoretical Benefit From an Adaptive Directional System in Reverberant Environments. ARLO 2004;5(4): 153–7.

CANADIAN HEARING REPORT 3 contents | Vol 4, Supplement 1

MESSAGE FROM THE EDITOR-IN CHIEF Official publication of the 1 Canadian Academy of Audiology 2 MESSAGE FROM THE GUEST EDITOR

5 BASING AMPLIFICATION RECOMMENDATIONS ON EVIDENCE Publication officielle de l’académie BY CATHERINE V. PALMER, PhD canadienne d’audiologie

E DITOR- IN-CHIEF /ÉDITEU RENCHEF 9 IMPROVING WATER RESISTANCE FOR HEARING Marshall Chasin, AuD., M.Sc., Reg. CASLPO, Director of Research, Musicians’ Clinics of Canada INSTRUMENTS BY WEILI LIN, PhD GUEST EDITOR Timothy D. Trine, PhD Chief Technical Officer, Starkey Laboratories, Inc. 16 VERIFICATION OF PRESCRIPTIVE FITTING THROUGH A HEARING AID M ANAGING E DITOR /D IRE CTEUR DE LA R ÉDACTION Scott Bryant, [email protected] BY JASON A. GALSTER, PhD & ELIZABETH A. GALSTER, AuD C ONTRIB UTORS 21 INTERACTION OF HEARING LOSS WITH Marshall Chasin, Brent Edwards, PSYCHOLOGICAL, SOCIOLOGICAL, AND Elizabeth Galster, Jason Galster, Weili Lin, COGNITIVE BEHAVIOUR Catherine Palmer, Tim Trine BY BRENT EDWARDS, PhD A RT D IRECTOR/DESIGN /DIRE CTEUR ARTISTIQUE /DESIGN Andrea Brierley, [email protected]

SALES AND CIRCULATION COORDINATOR./ COORDONATRICE DES VENTESETDELA DIFFUSION Brenda Robinson, [email protected] ACCOUNT ING /COMPTAB ILITÉ CANADIAN ACADEMY OF AUDIOLOGY Susan McClung 5160 Lampman Avenue, Burlington ON L7L 6K1 Tel.:416.494.6672, 800.264.5106, Fax: 416.494.9333 G ROUP P UBLISHER /CHE FDELADIRE CTION Web: www.canadianaudiology.ca, Email: [email protected] John D. Birkby, [email protected] BOARDOFDIRECTORS / CONSEIL DE DIRECTION ______Carri Johnson Ronald Choquette President PUBLIC AND COMMUNITY RELATIONS Canadian Hearing Report is published four times annually by Andrew John Publishing Near North Hearing Centre Campbellton Regional Hospital Inc. with offices at 115 King Street West, Dundas, On,Canada L9H 1V1. North Bay, Ontario Campbellton, New Brunswick We welcome editorial submissions but cannot assume responsibility or commitment for Glen Sutherland Krystelle Breton unsolicited material. Any editorial material, including photographs that are accepted from President-Elect Director an unsolicited contributor, will become the property of Andrew John Publishing Inc. Ontario Ministry of Children and Youth Services Oticon FEEDBACK Toronto,Ontario St-Lambert, Quebec We welcome your views and comments. Please send them to Andrew John Publishing Bill Campbell Jeff Smith Inc., 115 King Street West, Dundas, On, Canada L9H 1V1. Copyright 2009 by Andrew Past President Director John Publishing Inc. All rights reserved. Reprinting in part or in whole is forbidden Thunder Bay District Health Unit Peace Region Audiology Inc. without express written consent from the publisher. Thunder Bay,Ontario Grande Prairie, Alberta INDIVIDUAL COPIES Annick Ménard Bill Hodgetts Individual copies may be purchased for a price of $19.95 Canadian. Bulk orders may Treasurer Director be purchased at a discounted price with a minimum order of 25 copies. Please con- Siemens Hearing Instruments Inc. University of Alberta tact Ms. Brenda Robinson at (905) 628-4309 or brobinson@andrewjohn Cambridge, Ontario Edmonton, Alberta publishing.com for more information and specific pricing. Monica Pozer Susan Nelson-Oxford PublicationsAgreement Number 40025049 • ISSN 1718 1860 Secretary Director Return undeliverable Canadian Addresses to: Island Hearing Services Vancouver Island Health Authority Victoria, British Columbia Victoria, British Columbia

Erica Wong Rex Banks Director Director AJPI: 115 King Street West, Suite 220 Mount Sinai Hospital The Canadian Hearing Society Dundas Ontario L9H 1V1 Toronto, Ontario Toronto, Ontario Basing Amplification Recommendations on Evidence

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Table 1. Describing the quality of the design (from Cox, 2004) Table 2. Grades of recommendations (from Cox, 2004)

1. Systematic reviews and meta-analyses of A. Consistent level 1 or 2 studies randomized controlled trials B. Consistent level 3 or 4 studies or extrapolations 2. Randomized controlled trials from level 1or 2 studies 3. Non-randomized intervention studies C. Level 5 studies or extrapolations from level 3 or 4. Descriptive studies (cross-sectional surveys, cohort 4 studies studies, case-control designs) D. Level 6 evidence or troubling inconsistencies or 5. Case studies inconclusive studies of any level 6. Expert opinion

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100 100 90 90 80 80 70 70 60 60 50 Percent Correct 50 Percent Correct 40 40 30 30 Percent Correct (%) Percent Correct (%) 20 20 10 10 0 0 Aid 1 Aid 2 Aid 3 Aid 1 Aid 2 Aid 3 Hearing Aid Hearing Aid

8 CANADIAN HEARING REPORT Improving Water Resistance for Hearing Instruments

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Where,Wh SSL,L SSV,V andd LLVV are the interfacial free energies per unit area of the solid-liquid, solid-gas, and liquid-gas interfaces, respectively.

a. b.

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|

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immerSiOn teSt

teSt reSultS Salt FOg teSt FOr grOup 1 mOduleS

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CANADIAN HEARING REPORT 15 Verification of Prescriptive Fitting through a Hearing Aid

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110

100

90

80

70

60

50

40

30

20 Measured Real Ear Response (dB SPL) 10 125 250 500 1K 2K 4K 8K Frequency (Hz)

110

100

90

80

70

60

50

40

30

20 Measured Real Ear Response (dB SPL) 10 125 250 500 1K 2K 4K 8K Frequency (Hz)

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References 5. Strom K. The Hearing Review 2003 Dispenser 11. Munroe KJ and Toal S. Measuring The Real-Ear to Survey. Hear Rev 2003;22:24–38. Coupler Difference Transfer Function With an 1. American Academy of Audiology. Insert Earphone and a Hearing Instrument: Are Guidelines for the Audiologic Management of Adult 6. Kirkwood D. Survey Finds Most Dispensers Bullish, They The Same? Ear Hear 2005;26(1):27–34. Hearing Impairment. Reston, VA: Author. 2006. But Not On Over-The-Counter Devices. Retrieved July 1, 2009: Hear J 2004;57(3):19–30. 12. Schroeder AS, Pisa J, and Olson L. Results Reported http://www.audiology.org/resources/ On Two Clinical Trials of a Real-Ear System within a documentlibrary/documents/haguidelines.pdf. 7. Kirkwood, D. Survey: Dispensers Fitted More Hearing Aid. Hear J 2009;62(3):36–39. Hearing Aids in 2005 At Higher Prices. 2. Mueller HG, Hawkins DB, and Northern JL (Eds.). Hear J 2006;59(4):40–50. 13. Yanz JL and Galster JA. Integrating Real-Ear Probe Microphone Measurements. San Diego: Measurement Into Destiny and Zon Hearing Singular Publishing Group, Inc., 1992. 8. Ricketts TA. Oc Fittings: Considerations Regarding Instruments. Eden Prairie, MN: Starkey Laboratories. Prescriptive Methods and Function of Special 2008. 3. Australian Government Department of Health and Hearing Aid Features. San Antonio, TX: Author. Ageing. Australian Government Hearing Services Retrieved June 24, 2009: Program: Service Provider Contract. Canberra, http://www.audiologyonline.com. Australia: Author. 2007. 9. Aarts NL and Caffee CS. Manufacturer Predicted 4. British Society of Audiology and British Academy of and Measured Rear Values in Adult Hearing Aid Audiology. (2007). Guidance on the Use Of Real Fitting Accuracy and Clinical Usefulness. Int J Audiol Ear Measurement to Verify the Fitting of Digital 2005;44(5):293–301. Signal Processing Hearing Aids. Reading, UK. Author. Retrieved July 9, 2009: 10. Aazh H and Moore BCJ. The Value of Routine Real http://www.thebsa.org.uk/docs/recpro/rem.pdf. Ear Measurement of the Gain of Digital Hearing Aids. J Am Acad Audiol 2007;18:653–64.

20 CANADIAN HEARING REPORT Interaction of Hearing Loss with Psychological, Sociological, and Cognitive Behaviour

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