UC Irvine

Objective

Compare brain potentials to consonant vowels (CVs) as a function of both voice onset times (VOTs) and consonant position; initial (CV) versus second (VCV).

Methods

Auditory cortical potentials (N100, P200, N200, and a late slow negativity, (SN) were recorded from scalp electrodes in twelve normal hearing subjects to consonant vowels in initial position (CVs: /du/ and /tu/), in second position (VCVs: /udu/ and /utu/), and to vowels alone (V: /u/) and paired (VVs: /uu/) separated in time to simulate consonant voice onset times (VOTs).

Results

CVs evoked "acoustic onset" N100s of similar latency but larger amplitudes to /du/ than /tu/. CVs preceded by a vowel (VCVs) evoked "acoustic change" N100s with longer latencies to /utu/ than /udu/. Their absolute latency difference was less than the corresponding VOT difference. The SN following N100 to VCVs was larger to /utu/ than /udu/. Paired vowels (/uu/) separated by intervals corresponding to consonant VOTs evoked N100s with latency differences equal to the simulated VOT differences and SNs of similar amplitudes. Noise masking resulted in VCV N100 latency differences that were now equal to consonant VOT differences. Brain activations by CVs, VCVs, and VVs were maximal in right temporal lobe.

Conclusion

Auditory cortical activities to CVs are sensitive to: (1) position of the CV in the utterance; (2) VOTs of consonants; and (3) noise masking.

Significance

VOTs of stop consonants affect auditory cortical activities differently as a function of the position of the consonant in the utterance.