Distortion product otoacoustic emission level maps from normal and noise-damaged cochleae

Abstract

Distortion product otoacoustic emission (DPOAE) level mapping may be useful for detecting noise-induced hearing loss (NIHL) early. Employing DPOAE mapping effectively requires knowledge of the optimal mapping parameters to use for detecting noise-induced changes. The goal of this project was to show the map regions that differ most between normal and noise-damaged cochlea to determine the optimal mapping parameters for detecting NIHL. DPOAE level maps were generated for the 2f 1 -f 2 and the 2f 2 -f 1 DPOAEs for 17 normal hearing male subjects and 19 male subjects with NIHL. DPOAEs were measured in DPOAE frequency steps of approximately 44 Hz from 0.5 kHz to 6 kHz using constant f 2 /f 1 ratios incremented in 0.025 steps from 1.025 to 1.5 using both unequal-level (L1,L2 = 65,55 dB sound pressure level (SPL)) and equi-level (L1,L2 = 75,75 dB SPL) stimulus paradigms. Maximal responses for the 2f 2 -f 1 emission at L1,L2 = 65,55 dB SPL were found at lower ratios compared to previous studies. The map regions where NIHL eliminated or reduced DPOAE magnitude were identified. DPOAE level mapping using higher-level, equi-level primaries produced significantly more detectable emissions particularly for the 2f 2 -f 1 emission. The data from this study can be used to optimize DPOAE level mapping parameters for tracking noise-exposed subjects longitudinally.

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“…The results of Mink's study on using the map of emission distortion levels of DPOAEs in Coclé damaged by noise and healthy Coclé showed that the DPOAEs range of group with NIHL is significantly weaker with P ≤ 0.01 compare to the healthy group. [25] According to the results of the present study and previous studies, it seems that DPOAE detects hearing loss caused by noise one phase earlier compare to PTA. However, future studies should try to provide more valid documents on the levels of DPOAE and controlling variables such as duration of exposition, smoking, and blood pressure levels.…”

“…[11,12,21] OAE is an objective test which can be more affordable compared to PTA due to its being cheap, act quickly and save time, not to need acoustic room, and sensitivity to hear losing. [13,[22][23][24][25] The study was conducted using PTA and OAE tests in two groups, i.e. control group including people exposed to industrial noise and without NIHL and experimental group including people with NIHL.…”

ICBEN review of research on the biological effects of noise 2011-2014

“…Effort was exerted to optimize distortion-product otoacoustic emission (DPOAE) for tracking noise-exposed subjects longitudinally. [ 41 ] Although the first observation in construction workers was promising in the aspect of the higher sensitivity of DPOAE (mainly at 4 kHz) in monitoring early signs of NIHL, a 10-year prospective study showed no advantage of this method over standard audiometry. [ 13 ] One of the limitations of translating the data is that significant individual otoacoustic emission (OAE) changes do not necessarily follow the same pattern as the group-averaged results.…”

Methylprednisolone use during radiotherapy extenuates hearing loss in patients with nasopharyngeal carcinoma

“…The DPOAE level reflects the function of the outer hair cells in the cochlea. 17 Our results indicated that there outer hair cell damage occurred early after radiotherapy. The hair cell damage after radiotherapy resulted from several causes.…”

“…We found that the DPOAE levels decreased after irradiation. The DPOAE level reflects the function of the outer hair cells in the cochlea . Our results indicated that there outer hair cell damage occurred early after radiotherapy.…”