MMN and P3 auditory evoked potentials within and across phonetic categories

The mismatch negativity (MMN) and P300 of the auditory evoked response potentials were studied within and across phonetic categories of /ba/ and /pa/ differing in voice onset time. The MMN and P300 responses were present in all within and across phonetic conditions suggesting a discrimination at both temporal areas of the ERP. There were no differences in the MMN amplitude or latency measures. P300 amplitude was found to be significantly larger for the across category conditions. These results suggest that categorical processing may not occur in the temporal domain of the MMN and may first occur in the time period of the P300. Measures of acoustic discrimination and linguistic categorization at the level of central processing are of great clinical value.