Pre-attentive Perceptual Integration of Tones and Vowels

The feature-integration theory of attention posits that auditory features are first processed independently at early stages. We tested the theory by examining the neural processing integrality of vowels and tones at the early pre-attentive auditory level. Twenty native Cantonese listeners participated in the event-related potential (ERP) experiment. We adopted the mismatch negativity (MMN) additivity approach, and elicited three types of mismatch negativities (tone deviant, vowel deviant and double-tone-vowel deviant) using a passive oddball paradigm. We found that the mismatch negativity of the double deviant was not additive by the mismatch negativities of the single deviants. The results indicate that tones and vowels are processed integrally by the same neuronal population at the early pre-attentive auditory level. Potential implications to theories and models of speech perception will be discussed.