Abstract
ObjectiveCompare brain potentials to consonant vowels (CVs) as a function of both voice onset times (VOTs) and consonant position; initial (CV) versus second (VCV). MethodsAuditory 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). ResultsCVs 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. ConclusionAuditory cortical activities to CVs are sensitive to: (1) position of the CV in the utterance; (2) VOTs of consonants; and (3) noise masking. SignificanceVOTs of stop consonants affect auditory cortical activities differently as a function of the position of the consonant in the utterance.
Highlights
Stop consonant-vowel (CV) utterances (e.g., /du/ and /tu/), are distinguished by acoustic differences of the time between onset of the consonant (‘‘stop release burst’’) and onset of the following vowel (‘‘voicing’’)
The results of this study show that cortical activity related to voice onset time (VOT) of the consonant changed as a function of consonant position in the utterance
When the consonant is in initial position (CV), an onset N100 response is observed whose amplitude, but not latency, varied inversely with VOT
Summary
Stop consonant-vowel (CV) utterances (e.g., /du/ and /tu/), are distinguished by acoustic differences of the time between onset of the consonant (‘‘stop release burst’’) and onset of the following vowel (‘‘voicing’’). The difference in ms between the onsets of the consonant and the vowel is known as ‘‘voice onset time’’ or VOT (Lisker and Abramson, 1964). VOTs are relatively brief (45 ms in English). VOTs that fall within these boundaries, are more variably classified as /t/ or /d/ when compared to short or long duration VOTs. The temporal boundaries described above are typical for English speakers (Lisker and Abramson, 1964) but can differ depending on the native language of the subject (e.g., Williams, 1977 for Spanish; Laufer, 1998 and Horev et al, 2007 for Hebrew)
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