Page 14 - Winter Issue 2018
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Age-Related Hearing Loss
A ‘&a—v—%¢.§'_. .
E 20
E 40 _\ . u
g 60
95’ so
100 Older-Normal Metabolic Sensory Metabolic 4- Sensory
0.250.5 1 2 4 8 0.25 0.5 1 2 4 8 0.25 0.5 1 2 4 8 0.25 0.5 1 2 4 8
Frequency (kHz)

Figure 3. Example audiograms are provided for the four major audiometric categories (phenotypes). Shaded areas correspond to the dis-
tribution of data labeled in these categories by experts. The “Older—Normal” and “Metabolic” phenotypes are similar to the audiograms for
younger and older adults in Figure 1, respectively The “Sensory” phenotype shows normal hearing in the low frequencies, dropping to a
moderately severe hearing loss in the high frequencies, and the “Metabolic + Sensory” audiogram shows a moderate hearing loss in the low
frequencies, dropping to a severe hearing loss in the high frequencies. Modified from Vaden et al. (2017), with permission.

the superior olivary complex in the brainstem to the outer The Audingr-am Does Not Predict

hair cells (depicted in Figure 2). Refer to Lonsbury-Martin Speech Understanding in Noise

et al. (2017) and Brownell (2017) for more detailed descrip- Patients with more severe hearing loss can expect greater
tions of cochlear mechanics. speech understanding difficulties. A severe hearing loss
The most common type of hearing loss in older adults is sen- would eorrespond to thresholds in the range of 60'9O dB
sorineural hearing loss or presbyacusis. The audiograms of H1“ Nevertheless’ the audiogmm is not a good Predictor
individuals with presbyacusis can be classified into four main of Speeeh reeognition in reahstie eondifions’ Sueh as in a
eategories or Phenotypes (displayed in Figure 3): older nor_ noisy environment (Souza et al., 2007). Clinical measures of
mat’ metabolic’ Sensory) and metabolic + Sensory (Dubim et speech recognition in noise using words (Words-in-Noise
al., 2013). The metabolic category results from a loss of the [WIN] test; Wilson et 31” 2007) °r Sentences (Quick Speech
endocochlear potential (positive voltage found in cochlear in Noise [Q“iCkSIN] test; Kink)“ et 31» 2004) are becoming
tluid)_ Because the ehdoeoehlear Potential Supplies Power to more common in audiological evaluations. But even these
the outer hair eells (See Figure 2)) a decrease in the voltage tests may not account for all of the difficulties experienced
eah rediiee the hair eellS> ability to amplify incoming Sounds by older adults. Anderson et al. (2013a) investigated factors
The metabolic category is typified by a flat mild hearing loss contributing to the variance in self-assessment of hearing
in the low frequencies gradually sloping to greater hearing abilitl’ in Older adults “Sing the SPeeCh> SPatia1- ahd Quali-
loss in the high frequencies The sensory Phenotype is typi. ties of Hearing Questionnaire (SSQ; Gatehouse and Noble,
fied by a moderate-to-severe hearing loss in the high fre- 2004)- 111 3d<hti0h t0 the SSQ the test 11163511195 ihchlded
quencies that may result from exposure to noise or drugs P11f€'t0h€ thf9Sh01dSa Q11iCkS1N SCOYCS) and the f1‘€<l11€hCY
that are known to damage heating The metabolic + sensory following response (FFR), a scalp-recorded measure of elec-
Phenotype is characterized by a low-fiequency hearing loss trical activity that mirrors the timing and frequency aspects
similar to the metabolic phenotype and a moderate-to-se. of the auditory stimulus. They found that the pure-tone
vere high-frequency loss similar to the sensory phenotype_ thresholds and QuickSIN scores contributed to 15% Of the
At present, the relationship between these hearing loss pat- variance in the SSQ score, and the FFR to a speech sylla-
terns and real-world hearing difficulty remains unknown, ble accounted for an additional 15% of variance in the SSQ
but in the future, the identification of a specific audiometric score. Therefore, factors in addition to peripheral hearing
category may assist with determining possible hearing loss sensitivity, as indicated on the routine audiogram, may con-
etiologies and with management planning. tribute to speech understanding difficulties.

12 | Acuuseics Thday | Winter 2018

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