Cortical processing of change detection: Dissociation between natural vowels and two-frequency complex tones

One subject's responses for vowels and for complex tones consisting of the first two formant frequencies of the vowels. (A) Dipole locations (squares) in the left and right hemisphere. (B) Dipole waveforms for deviants (20%, solid line) and standards (80%, dashed line). The stimuli were presented in four blocks: i) the vowel /α/ as the deviant vs. the vowel /i/ as the standard; ii) /e/ vs. /i/; iii) complex tones representing /α/ formants (“/α/” tones) vs. complex tones representing /i/ formants; and iv) complex tones representing /e/ formants (“/e/” tones) vs. complex tones representing /i/ formants. (C) MMFs were calculated by subtracting the source waveform for the standard from that for the deviant.