Authors' Affiliations

Alexandria Lyons, Department of Audiology and Speech Language Pathology, College of Clinical and Rehabilitative Health Sciences, East Tennessee State University, Johnson City, Tennessee Sadie Mussler, Department of Audiology and Speech Language Pathology, College of Clinical and Rehabilitative Health Sciences, East Tennessee State University, Johnson City, Tennessee Dr. Jacek Smurzynski, Department of Audiology and Speech Language Pathology, College of Clinical and Rehabilitative Health Sciences, East Tennessee State University, Johnson City, Tennessee

Location

Culp Center Ballroom

Start Date

4-25-2023 9:00 AM

End Date

4-25-2023 11:00 AM

Poster Number

4

Faculty Sponsor’s Department

Audiology & Speech Pathology

Name of Project's Faculty Sponsor

Jacek Smurzynski

Classification of First Author

Graduate Student-Doctoral

Competition Type

Competitive

Type

Poster Presentation

Project's Category

Biological Sciences

Abstract or Artist's Statement

When the cochlea is stimulated with two primary tones (f1 and f2) some of the energy is reflected back and propagates via the middle ear into the outer ear. Due to cochlear nonlinearities, distortion product otoacoustic emissions (DPOAEs), may be detected by a probe microphone sealed in the ear canal. Reduced DPOAEs may indicate subclinical cochlear lesions. The relationship between hearing sensitivity and the strength of DPOAEs is debatable, especially in the extended high frequency (EHF) region (≥8 kHz). Monitoring cochlea function corresponding to the EHF range is important for detecting early stages of hearing loss, which typically begins above 8 kHz. Complex interactions of high-frequency pure-tones in the ear canal result in standing waves that increases test-retest variability of DPOAEs measured for f2≥6 kHz. The aim of the project was to evaluate reliability of DPOAEs measured up to 12 kHz with a system used routinely in audiology clinics. Thirty-one adults (age, 18-30 yrs) with normal middle-ear function and normal hearing thresholds in the conventional region (≤8 kHz) participated. The EHF audiometry was performed for frequencies up to 16 kHz. The DPOAE data were collected for the f2 frequency varied from 1.5 to 12 kHz, twice for each ear with the probe removed and then repositioned after the first test. The EHF audiometric data of four participants showed elevated thresholds. Their DPOAEs were reduced or absent for f2≥9 kHz, i.e., supporting the sensitivity of DPOAEs for cochlear hearing loss above the conventional audiometry frequency range. Mean and standard deviations of DPOAE levels were calculated separately for the left and the right ears of subjects with normal EHF thresholds. There were no differences between mean DPOAE values in the left and the right ears. The intersubject variability of the DPOAE levels was moderate (SD≈6 dB or lower) but it increased significantly in the 12-kHz region, per the F-test for variances, possibly due to 1. effects of standing waves on the high-frequency DPOAE reliability and/or 2. subclinical pathology in the most basal portion (i.e., high-frequency region) of the cochlea. For each ear, absolute values of differences between test/retest levels of detectable DPOAEs were calculated. ANOVA showed the main effect of frequency for the data collected in the left and the right ears. Post-hoc analyses indicated that test/retest variability of DPOAEs was rather constant for f2 frequencies up to 10 kHz, but a statistically significant increase of test/retest variability for f2 of 11 and 12 kHz was found. This aspect needs to be considered when using DPOAE tests for longitudinal monitoring of cochlear function in the basal portion. Nevertheless, combining behavioral thresholds with DPOAEs collected for the EHF range is vital for detecting the initial stage of the cochlear pathology corresponding to the high-frequency region, e.g., due to ototoxicity or aging of the cochlea.

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Apr 25th, 9:00 AM Apr 25th, 11:00 AM

Evaluation of Pure-Tone Thresholds and Distortion Product Otoacoustic Emissions Measured in the Extended High Frequency Region

Culp Center Ballroom

When the cochlea is stimulated with two primary tones (f1 and f2) some of the energy is reflected back and propagates via the middle ear into the outer ear. Due to cochlear nonlinearities, distortion product otoacoustic emissions (DPOAEs), may be detected by a probe microphone sealed in the ear canal. Reduced DPOAEs may indicate subclinical cochlear lesions. The relationship between hearing sensitivity and the strength of DPOAEs is debatable, especially in the extended high frequency (EHF) region (≥8 kHz). Monitoring cochlea function corresponding to the EHF range is important for detecting early stages of hearing loss, which typically begins above 8 kHz. Complex interactions of high-frequency pure-tones in the ear canal result in standing waves that increases test-retest variability of DPOAEs measured for f2≥6 kHz. The aim of the project was to evaluate reliability of DPOAEs measured up to 12 kHz with a system used routinely in audiology clinics. Thirty-one adults (age, 18-30 yrs) with normal middle-ear function and normal hearing thresholds in the conventional region (≤8 kHz) participated. The EHF audiometry was performed for frequencies up to 16 kHz. The DPOAE data were collected for the f2 frequency varied from 1.5 to 12 kHz, twice for each ear with the probe removed and then repositioned after the first test. The EHF audiometric data of four participants showed elevated thresholds. Their DPOAEs were reduced or absent for f2≥9 kHz, i.e., supporting the sensitivity of DPOAEs for cochlear hearing loss above the conventional audiometry frequency range. Mean and standard deviations of DPOAE levels were calculated separately for the left and the right ears of subjects with normal EHF thresholds. There were no differences between mean DPOAE values in the left and the right ears. The intersubject variability of the DPOAE levels was moderate (SD≈6 dB or lower) but it increased significantly in the 12-kHz region, per the F-test for variances, possibly due to 1. effects of standing waves on the high-frequency DPOAE reliability and/or 2. subclinical pathology in the most basal portion (i.e., high-frequency region) of the cochlea. For each ear, absolute values of differences between test/retest levels of detectable DPOAEs were calculated. ANOVA showed the main effect of frequency for the data collected in the left and the right ears. Post-hoc analyses indicated that test/retest variability of DPOAEs was rather constant for f2 frequencies up to 10 kHz, but a statistically significant increase of test/retest variability for f2 of 11 and 12 kHz was found. This aspect needs to be considered when using DPOAE tests for longitudinal monitoring of cochlear function in the basal portion. Nevertheless, combining behavioral thresholds with DPOAEs collected for the EHF range is vital for detecting the initial stage of the cochlear pathology corresponding to the high-frequency region, e.g., due to ototoxicity or aging of the cochlea.