Human auditory evoked mismatch field amplitudes vary as a function of vowel duration in healthy first-language speakers.
Previous auditory studies demonstrated that vowel shortening elicited a more prominent mismatch component than its lengthening in event-related potentials (ERP) and magnetoencephalography (MEG). Based on these findings, the current study investigated whether the magnetic mismatch field (MMF) component would be generated by vowel shortening of various degrees to determine a neuronal response threshold of pre-attentive deviation detection. Behavioral pre-test data revealed that while listening to Japanese short-duration (100%: reference), long-duration (180%), and other in-between duration-synthesized types, healthy native speakers of Japanese failed to clearly categorize 140-124% durations as either short or long words, while categorizing 108-116% durations as short words and 148-172% durations as long. Following these results, MEG responses were recorded with a whole-head 148-channel magnetometer, as subjects listened to 100% standard and five deviant durations (124, 132, 140, 148, 180%). MEG results showed that the above-32% duration decrements (180-->100%, 148-->100%) elicited a more prominent MMF than the others, the MMF amplitudes increasing linearly to the degree of duration deviance, and that neuronal responses correlated with behavioral word-categorization accuracy.
International Student Center, Ochanomizu University, Tokyo, Japan.
Mayako
M
Inouchi
Mikio
M
Kubota
Katsuya
K
Ohta
Yasuhiro
Y
Shirahama
Atsuko
A
Takashima
Toshihiro
T
Horiguchi
Eisuke
E
Matsushima
D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D001307:Auditory Perception / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007802:Language; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D010700:Phonetics; D012043:Regression, Psychology; D013997:Time Factors