Brainstem-cortical functional connectivity for speech is differentially challenged by noise and reverberation.

Brainstem-cortical functional connectivity for speech is differentially challenged by noise and reverberation.
Hear Res. 2018 May 26;:
Authors: Bidelman GM, Davis MK, Pridgen MH
Abstract
Everyday speech perception is challenged by external acoustic interferences that hinder verbal communication. Here, we directly compared how different levels of the auditory system (brainstem vs. cortex) code speech and how their neural representations are affected by two acoustic stressors: noise and reverberation. We recorded multichannel (64 ch) brainstem frequency-following responses (FFRs) and cortical event-related potentials (ERPs) simultaneously in normal hearing individuals to speech sounds presented in mild and moderate levels of noise and reverb. We matched signal-to-noise and direct-to-reverberant ratios to equate the severity between classes of interference. Electrode recordings were parsed into source waveforms to assess the relative contribution of region-specific brain areas [i.e., brainstem (BS), primary auditory cortex (A1), inferior frontal gyrus (IFG)]. Results showed that reverberation was less detrimental to (and in some cases facilitated) the neural encoding of speech compared to additive noise. Inter-regional correlations revealed associations between BS and A1 responses, suggesting subcortical speech representations influence higher auditory-cortical areas. Functional connectivity analyses further showed that directed signali...

Source: Hearing Research - May 26, 2018 Category: Audiology Authors: Bidelman GM, Davis MK, Pridgen MH Tags: Hear Res Source Type: research