Communicating in challenging environments noise and reverberation, the frequency-following response: A window into human communication

Author(s): Bidelman GM


In everyday listening situations, speech perception is challenged by interfering noise and other adverse room acoustics (e.g., reverberation). These intrusions hinder verbal communication and prevent audible access to salient cues by masking (noise) and smearing (“reverb”) spectrotemporal features of the speech signal. The brainstem frequency-following response (FFR) provides a detailed window into the early neural transcription of complex sounds and how normal and degraded speech signals are coded by the human auditory nervous system. This chapter provides an overview of noise-related and reverb-related changes in brainstem representations for speech as reflected in the scalp-recorded FFR. Although noise and reverberation affect behavior to a similar extent, they have a differential effect on neural speech representations, noise being a larger detriment to the speech code than reverberation. Acoustic interferences also produce distinct effects within the speech signal: the neural encoding of “timbre” is more affected than voice “pitch” cues. Applications for the FFR as a “biomarker” for understanding the neural basis and individual differences in degraded speech perception skills are also discussed.