The perception of speech sounds by the human brain as reflected by the mismatch negativity brain response

Abstract

This article outlines the contribution of the mismatch negativity (MMN) to our understanding of the perception of speech sounds by the human brain. MMN data indicate that each sound, both speech and non-speech, develops its neural representation (corresponding to the percept of this sound) in the neurophysiological substrate of auditory sensory memory. The accuracy of this representation, determining how accurately this sound is discriminated from the other sounds, can be probed with the MMN separately for any auditory feature (such as frequency or duration). Furthermore, the accuracy of discriminating different speech sounds can also be evaluated by using the MMN. In addition, the MMN data show that the perception of the phonemes, and probably also of larger linguistic units (syllables and words), is based on permanent language-specific phonetic traces that can be located with magnetoencephalographic (MEG) recordings in the posterior part of the left-hemisphere auditory cortex. These traces appear to serve as recognition models for the corresponding speech sounds in speech perception. MMN studies further suggest that these language-specific traces for the mother tongue develop during the first few months of life. Moreover, the MMN can also be used as an index of the development of such traces for a foreign language learned later in life.