The influence of temporal stimulus changes on speech-evoked potentials revealed by approximations of tone-evoked waveforms.
OBJECTIVE
The aim of the study was to determine whether cortical auditory potentials evoked by monosyllabic words beginning with a single consonant can be attributed to a combination of two N1/P2 complexes, temporally separated by voice-onset time (VOT).


METHODS
Cortical auditory-evoked potentials were recorded in seven normal-hearing young adults in response to two types of stimuli (a) simple tone bursts and (b) five monosyllabic words with different VOTs. Cortical burst responses (mainly consisting of N1 and P2) formed the basic functions for the simulation of speech-evoked potentials. Actually, two basic functions were created with respect to different VOTs of the speech sounds. An optimization procedure was used to determine the relative contributions of the two N1/P2 complexes.


RESULTS
Speech-evoked potentials differed clearly across the stimuli. In all subjects, close matches of the synthetic and the measured waveforms could be gained for all speech sounds. The relative magnitudes of the constituent complexes differed among stimuli.


CONCLUSIONS
The auditory-evoked response to a monosyllabic speech sound with short VOT can be represented by two overlapping N1/P2 complexes-one to syllable onset and the second to vowel onset. The temporal separation between the two components is well predicted by VOT, but the relative amplitudes vary across syllables. Observed variability in the fitting accuracy across subjects is small.
Burger
Martin
M
Department of Phoniatrics and Pediatric Audiology, University Hospital Erlangen, Bohlenplatz 21, Erlangen, Germany. burger.martin@vdi.de
Hoppe
Ulrich
U
Lohscheller
Jörg
J
Eysholdt
Ulrich
U
Döllinger
Michael
M
D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D010700:Phonetics; D011930:Reaction Time; D013997:Time Factors; D014831:Voice; D055815:Young Adult