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Home , Audiogram, Audiometry, Conductive hearing loss, Hearing test, Pure tone audiometry, Tympanometry

Audiometric Test Procedures 101 This information is meant to help you better understand the various test procedures as well as some of the terms you might see on an audiometric report.

By Larry Medwetsky individual could, in fact, exhibit nor- In the previous issue of mal hearing acuity across these three Loss Magazine, I provided an over- Anyone who has ever had their , yet, exhibit a significant view concerning hearing threshold hearing tested should know how in the higher frequencies results as recorded on the to read the audiogram, but that’s (3000-8000 Hz). Thus, it is important and an explanation of the pure-tone easier said than done. Hopefully, to examine the SRT in the context of audiogram. In this article, I will after reading this article you will the other audiometric test findings. describe various test procedures have a greater understanding of the Speech Awareness Threshold that are typically administered in principles discussed and use your (SAT): an audiometric evaluation and what knowledge going forward—be it in Compound words are pre- information the tests provide. reviewing results you sented, the goal being to determine already have or when discussing your the softest level one can detect the Audiometric Test Procedures results at your next hearing test. presence of words. This test is often Pure-tone : Tones of used when an individual’s hearing loss different frequencies are presented; the is so great that the person is unable goal is to find the softest level relatively flat hearing losses, and the to recognize/repeat the words, yet is which one can hear (threshold) the average of 500 and 1000 Hz for those aware that words have been presented. different tones. This test is typically with significantly sloping hearing Similar to the SRT, a person could administered in one of two ways: air- losses (i.e., the individual’s hearing present with an SAT value within the conduction audiometry—involving thresholds drop sharply with increas- normal range, yet exhibit significant the use of head/ phones; and, bone- ing ). hearing difficulty. conduction audiometry—involving Speech Reception Thresholds For example, an individual might the placement of a vibrating device on often serve as a reference for the au- have a hearing threshold of 15dB HL a person’s skull. diologist in determining presentation at 250 Hz and reveal an SAT of 15dB By comparing the results from levels for other speech tests and as a HL, but for frequencies 500 to 8000 both procedures, one can determine if reliability check concerning the con- Hz exhibit a significant hearing loss. there is a conductive component pres- gruency of pure-tone test results and ent (some form of barrier interfering the SRT; that is, if the SRT and pure- Word Recognition Score (WRS): with the transmission of sound from tone averages are within 10 of Single syllable words are presented at the outer/ to the ). each other, audiologists can state with one or more listening levels: everyday In addition to any inner ear hearing loss certainty that the results agree with conversational level (approximately that might be present, the presence of each other. 50 dB HL); and, comfortable listen- a conductive component would result An SRT is considered to be ing (MCL) level. For most individuals in air-conduction thresholds over and normal if it falls in the range of -10 with a hearing loss the MCL is louder above the bone-conduction thresholds. to 25dB HL (Hearing Level). Even than the everyday conversational level though an individual might obtain a Determinations of word recogni- Speech Reception Threshold value within this normal range, this tion scores typically entail the presen- (SRT): Compound words (words does not always mean that he has tation of 25 or 50 words to each ear comprised of two smaller words, such completely normal hearing acuity. For separately and calculating the percent as cow-boy) are presented, the goal example, it is possible that the individ- of words correctly repeated. This test being to find the softest sound level ual’s thresholds in one ear are 15dB, can be administered either in quiet at which one can hear and repeat ap- 25dB, and 35dB HL at 500, 1000 Hz, (without any competing noise) or proximately one-half of the compound and 2000 Hz respectively. The average in the presence of noise. Speech words correctly. The SRT level of these thresholds is 25dB HL (nor- testing in noise can consist of different typically obtained approximates the mal range), yet the individual presents types of noise, such as a shower noise average of 500, 1000 and 2000 Hz with a mild degree of hearing loss at or the noise of multiple people talking tonal thresholds for individuals with 2000 Hz. It is also possible that an in the background. The noise can 16 Hearing Loss Magazine also be presented at different levels one purchases hearing aids, results turn, provides information regard- relative to the level of the speech stimu- from this test are used to set the hear- ing the condition of the middle ear lus being presented to the listener. The ing aids’ maximum levels so (such as the possibility of middle ear scores that are obtained can provide that loud are not amplified by fluid being present, perforation of the the audiologist with key information, the hearing aids to a degree that they , etc.). including how well the individual: are intolerable. (1) can hear in quiet at an everyday Volume (ECV): This re- conversational level or if an individual Outer/Middle Ear Tests fers essentially to the volume of the ear has a relatively significant hearing loss Otoscopy: This entails the use of an canal in front of the tympanic mem- at his or her most comfortable listening instrument consisting of a magnifying brane and is derived through the use level; and, (2) can hear in the presence lens and a light for examining the ex- of . ECV varies in size, of background noise. ternal canal and tympanic membrane being approximately double in size for For many individuals with hear- (eardrum). This visualization allows adults as compared to young children. ing loss, the audiologist might admin- the audiologist to determine if ear Ear canal volume can be affected by a ister this test at both everyday conver- wax is blocking the ear canal or other number of conditions. For example, if sational level and MCL. This allows for foreign material is present, and, if so, there is a TM perforation, ECV will a comparison of performance at both its extent; and if there is a possibil- be very large since it will also include levels and provides an indication as ity of some form of outer/middle ear the middle ear space behind the TM. to whether hearing aids are likely to pathology. On the other hand, if there is much be beneficial (i.e., if the individual wax, then the ECV will likely be does significantly better at the louder, Tympanometry: The audiologist reduced in size. MCL level). places a device with a rubber tip into the person’s ear canal which creates a Testing:This test Loudness Discomfort Level (LDL): gradual change in the ear’s air pres- might be done subsequent to tympa- The LDL is the loudest level one can sure. The results indicate how well the nometry with the rubber tip still in the tolerate various sounds without the tympanic membrane (eardrum) moves ear canal. When loud sounds are pre- sound being uncomfortably loud. If relative to normative values, and in continued on page 18

Like HearingLossAssociation on Facebook September/October 2014 17 Audiometric cont. from page 17 R (right) and L (left) at both 500 and single syllable words at his or her most 3,000 Hz.These represent the tonal comfortable listening level (MCL) sented a small muscle in the middle ear Loudness Discomfort Level (LDL) since everyday conversation level usually contracts. This muscle contrac- values at these frequencies. For this (50dB HL) would be too soft or tion is called the acoustic reflex (or the individual, the LDL values occur inaudible. In this case, the listener’s middle ear muscle reflex). The purpose at levels that an audiologist would reported MCL in both was 80dB is to provide the audiologist with valu- typically expect for this degree/type HL. Interestingly, this intensity level able information regarding the health of hearing loss. is similar to what a normal hearing in- of the middle and inner ears, as well as Overall, the range between dividual would experience if a person other structures like the auditory nerve thresholds and LDL, though somewhat yelled at a distance of six inches. and parts of the brainstem. reduced when compared to those with Upon obtaining an individual’s normal hearing (more so at 3000 Hz), MCLs, 25 or 50 single-syllable word Case Example is sufficient enough for a ’s lists are presented. In this case, the To help you integrate the informa- circuitry/accompanying algorithms to client was presented with 50 words tion that I have presented here, I amplify most speech sounds without to each ear, one ear at a time and was have crafted audiometric findings significant difficulty, at least in the able to obtain scores of 80 percent and for an imaginary case; the findings range extending from 250 to 4000 Hz. 84 percent in the right and left ears, are displayed in the graphic on page respectively. Another way of stating 17. The first results I will review are Speech Audiometry Results this is that the listener was able to those shown in the pure-tone audio- This individual’s hearing sensitivity repeat 40 out of 50 words correctly in gram. The X (left ear) and O (right was sufficient for hearing and recog- the right ear and 42 out of 50 words ear) indicate the softest levels that nizing spondees (obtaining speech correctly in the left ear. an individual can hear (thresholds) reception thresholds) at a level of 50 These scores do not mean that via air-conduction audiometry using dB HL in the right ear and 55 dB HL this individual has 80 percent hearing either headphones or earphones, while in the left ear. The normal range for in the right ear and 84 percent in the the < indicate the thresholds obtained SRT is from -10 dB to 25 dB HL, left ear; the percentages just reflect his via bone-conduction audiometry. therefore, this individual’s SRTs are or her particular test performance in The fact that the results do not both beyond the normal range. These this specific listening condition. reveal a significant (less than a 10dB) SRT values approximate everyday difference between air- and bone-con- conversation level (50 dB HL), which Outer/Middle Ear Test Results duction thresholds, we do not suspect a is also typical of the most comfortable The information displayed on the . That is, a con- listening level for most normal hearing right side of the graphic on page 17 re- ductive hearing loss would indicate that individuals. veals key findings relative to the outer/ something is preventing sound from Yet, this person was just barely middle ears. Note that these proce- being conducted through the outer able to hear and repeat these words at dures are usually administered before and middle ear systems causing better this level in the right ear and unable to pure-tone and speech audiometry, thresholds to be obtained by bone ‘] hear the words in the left ear. In exam- with otoscopy always being performed conduction than via air conduction. ining the hearing loss configuration of first. This individual’s otoscopic results Because air and bone-conduction both ears, they appear to be relatively revealed both ear canals to be clear, thresholds are essentially the same for flat (the thresholds drop gradually). with no present in either ear. all test frequencies we can assume that Because we average the thresholds The ear canal volumes (measured in there is no blockage/pathology involv- at 250, 500, and 1000 Hz for flat/ cubic centimeters—cm3) as deter- ing the outer/middle ears. Since we relatively flat hearing losses, this mined from tympanometry were 1.5 know there is a hearing loss, but have audiogram reveals pure-tone averages and 1.7 cm3 for the right and left ears, ruled out conductive involvement, (PTA) of 47dB hearing loss and 45dB both within norms for adults. we can deduce that the cause of the HL for the right and left ears, respec- As mentioned earlier, the hearing loss lies within the sensory tively. Since each of these PTA values primary goal of tympanometry is to system, and therefore, we identify is within 10dB of the SRT obtained assess how well the eardrum moves. a sensorineural hearing loss. for each ear, we can state with good By examining where the peak of the The overall results indicate a certainty that the SRT and PTA tympanometric tracings occur, one can bilateral mild sloping gradually to a findings agree with each other, and determine the individual’s middle ear severe sensorineural hearing loss. therefore appear to be reliable. pressure in each ear and accompanying In looking at the audiogram, The next step involved examin- tympanic membrane (TM) mobil- the reader will also note the symbols ing this individual’s ability to repeat ity. Middle ear pressure indicates the

18 Hearing Loss Magazine Visit us at hearingloss.org and follow @HLAA on Twitter extent to which the middle ear cavity present. In these instances, the audiol- Acknowledgements (the space behind the TM) is being ogist might administer additional tests I would like to recognize some aerated properly by the Eustachian and/or refer the client to a physician individuals who helped me with this tube (a structure that connects the for further evaluation and possible article: my colleague, Dr. Chizuko nasal cavity to the middle ear space). treatment. Tamaki, who helped me to develop all Tympanic membrane mobility If no medical issues appear to aspects of Figure 1 and under whose refers to how effectively the TM and be present, then based on the degree guidance I continue to develop my the adjoining middle ear are of hearing loss and the extent of listen- computer skills; Lucas Lancaster, a transmitting sounds from the outer to ing difficulties being experienced, Ph.D. student in at Gal- inner ear. The X-axis displays middle an audiologist might recommend laudet University who did a great job ear pressure from +200 decaPascals to the client: communication strate- of reviewing this article; and my eldest (daPa) to -400 daPa (normal range gies; hearing aids or cochlear implant; son Adam, who served as a novice being from +50 to -150 daPa). The hearing assistive technology, such as an reader to this area and informed me Y-axis indicates TM mobility in mil- amplified phone or TV listener; and/ as to how I could improve the article. limhos (mmho), with typical adult or involvement in an aural rehabilita- Much thanks to all of you. HLM values ranging from 0.3 to 1.5 mmho. tion program. In this individual’s case, tympanom- Larry Medwetsky, etry revealed tracings that fall within Final Thoughts Ph.D., graduated the white shaded regions (within the Based on the information obtained, an with a master’s normal range), thus, revealing bilat- audiologist can ascertain if a hearing degree in audiol- eral, normal TM mobility. loss is present in either or both ears, ogy from McGill Acoustic reflex testing revealed and, if so, its type and severity. In ad- University, Mon- reflexes in both ears in response to dition, an audiologist is able to glean treal and a doctor- stimuli presented at levels consis- information relative to the listener’s ate in Speech and tent with the degree of sensorineural ability to understand speech in quiet Hearing Sciences hearing loss present (based on pub- or noise. I focused primarily on as- in 1994 from the lished values derived from empirical sessment procedures that are typically Graduate Center, research). The presence of normal administered by an audiologist. There City University of New York. He has tympanograms as well as acoustic are many other assessments that can be served as an educational audiologist, reflex findings that are consistent with conducted, depending on the present- vice president of clinical services in a the degree of hearing loss present are ing case and the audiologist’s/client’s large speech and hearing clinic, and both congruent with the presence of goals for the assessment. I hope that I is presently an associate professor at a sensorineural hearing loss, and, in have demystified somewhat the terms, Gallaudet University in the Depart- turn, provides greater confidence in graphs and numbers displayed on ment of Hearing, Speech and Language the other findings. the audiometric report and, in turn, Sciences. Dr. Medwetsky has published empowered recipients of audiological and presented on many different topics Hearing Assessment services to engage in a more meaning- with a special focus on the underlying Results Summary ful dialog with your audiologist. speech processes and deficits in both The client revealed a bilateral mild If you have any questions or individuals with normal hearing sloping gradually to a severe sensori- comments, please feel free to contact and hearing loss. neural hearing loss. Otoscopic exami- me at [email protected]. nation revealed both ears canals to be clear, while tympanometric findings revealed normal middle ear pressure Some Additional Terms and mobility in both ears. Word rec- Bilateral/Unilateral: In this context, bilateral refers to occurring in both ears, ognition scores in quiet are consistent while unilateral refers to occurring in one ear. For example, a bilateral hearing loss with the degree of hearing loss present. refers to a hearing loss of both the right and left ears, while a In the case example I provided, the cli- means the hearing loss is only in one of the ears. ent did not appear to have any issues involving the outer/middle ear, or the Symmetrical/Asymmetrical: Symmetrical refers to the similarity in hearing balance organ and/or auditory nerve. sensitivity from one ear to the other; that is, symmetrical hearing reveals the same However, it is sometimes the type and degree of hearing loss (or normal hearing) in both ears. Asymmetrical case that the and hearing refers to hearing sensitivity that is significantly different between the two test results suggest a disorder to be ears; this difference could be at all frequencies or just some of them.HLM

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