title: Neural Segregation of Concurrent Speech: Effects of Background Noise and Reverberation on Auditory Scene Analysis in the Ventral Cochlear Nucleus.
abstract: Concurrent complex sounds (e.g., two voices speaking at once) are perceptually disentangled into separate "auditory objects". This neural processing often occurs in the presence of acoustic-signal distortions from noise and reverberation (e.g., in a busy restaurant). A difference in periodicity between sounds is a strong segregation cue under quiet, anechoic conditions. However, noise and reverberation exert differential effects on speech intelligibility under "cocktail-party" listening conditions. Previous neurophysiological studies have concentrated on understanding auditory scene analysis under ideal listening conditions. Here, we examine the effects of noise and reverberation on periodicity-based neural segregation of concurrent vowels /a/ and /i/, in the responses of single units in the guinea-pig ventral cochlear nucleus (VCN): the first processing station of the auditory brain stem. In line with human psychoacoustic data, we find reverberation significantly impairs segregation when vowels have an intonated pitch contour, but not when they are spoken on a monotone. In contrast, noise impairs segregation independent of intonation pattern. These results are informative for models of speech processing under ecologically valid listening conditions, where noise and reverberation abound.
authors.affiliation: Centre for the Neural Basis of Hearing, The Physiological Laboratory, Department of Physiology, Development and Neuroscience, Downing Street, CB2 3EG, Cambridge, UK. sayles.m@gmail.com.|Laboratory of Auditory Neurophysiology, Campus Gasthuisberg, O&N II, Herestraat 49-bus 1021, 3000, Leuven, Belgium. sayles.m@gmail.com.
authors.forename: Mark
authors.initials: M
authors.lastname: Sayles
authors.affiliation: Centre for the Neural Basis of Hearing, The Physiological Laboratory, Department of Physiology, Development and Neuroscience, Downing Street, CB2 3EG, Cambridge, UK.
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Stasiak
authors.affiliation: Centre for the Neural Basis of Hearing, The Physiological Laboratory, Department of Physiology, Development and Neuroscience, Downing Street, CB2 3EG, Cambridge, UK.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Winter
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000502:physiology; D017626:Cochlear Nucleus / Q000502:physiology*; D006168:Guinea Pigs; D009622:Noise; D011571:Psychoacoustics; D013016:Sound; D013065:Speech Intelligibility; D013067:Speech Perception / Q000502:physiology*
keywords: Auditory scene analysis; Background noise; Brain stem; Cochlear nucleus; Concurrent speech; Double vowels; Inter-spike intervals; Intonation; Perceptual segregation; Reverberation; Temporal envelope; Vowels