Audiometric markers of cochlear Synaptopathy and speech in noise deficits in humans

Background Cochlear synaptopathy has been shown to precede hair cell loss and threshold shift over age. Cochlear synaptopathy is assumed to alter auditory information processing, whether accompanied by threshold elevations or not, and is a predicted contributor to speech-in-noise difficulties. It is crucial to understand the impact of cochlear synaptopathy on speech coding to develop effective therapeutic interventions.

Methods Here we examine young, middle-aged and older people (90) with and without hearing impairment for characteristic features of cochlear synaptopathy using pure tone audiometry, DPOAE (IO, DP-Gram, level maps), ABR, ASSR and speech understanding (OLSA), psychoacoustic speech test in noise and user-defined questionnaire for self-assessment of hearing in normal-hearing and hearing-impaired people of different ages. Using the OLSA threshold normalized by pure tone audiometry, we identify groups that have good or poor speech understanding in silence or in noise despite a comparable hearing threshold.

Results Interestingly, we find that the groups with good and poor speech comprehension, regardless of age, do not differ in their central auditory processing and temporal coding ability, but rather in their ability to discriminate vowel contrasts below or above phase locking in silence or in noise. There are different strategies that can be used to encode speech in silence and in noise above or below 1500 Hz.

Conclusion We discuss differential damage to auditory fiber components depending on different coding mechanisms for low or higher frequency stimuli as a cause of speech discrimination disorders.

Funding information In the submission process

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Artikel online veröffentlicht:
19. April 2024