The Perception and Neural Representation of Individual Harmonics in a Vowel Sound: A Behavioral and Auditory Brainstem Evoked Response Study

Abstract

Vowel perception primarily depends on the overall shape of the speech spectrum, which is imposed by the positions of the primary speech articulators. Voiced vowels also have a harmonic fine structure due to the activity of the vocal folds, and these harmonics give rise to synchronized activity in the brainstem. This synchronous firing may be useful for speech perception in noise and speaker discrimination, although it is unknown if the synchronized neural response to the harmonic increases perceptual audibility of the harmonic. The focus of the current study was to examine the relationship between the audibility of harmonics and the brainstem response to harmonics. The individual harmonics were found to be encoded in the brainstem, determined using brainstem frequency-following response recording, and the individual harmonics were audible to the individual, as determined using the pulsation threshold technique; however there was minimal relationship between the frequency-following response and perception of harmonics.