title: Development of the N1-P2 auditory evoked response to amplitude rise time and rate of formant transition of speech sounds.
abstract: We investigated the development of weighting strategies for acoustic cues by examining the morphology of the N1-P2 auditory evoked potential (AEP) to changes in amplitude rise time (ART) and rate of formant transition (RFT) of consonant-vowel (CV) pairs in 4-6-year olds and adults. In the AEP session, individuals listened passively to the CVs /ba/, /wa/, and a /ba/ with a superimposed slower-rising /wa/ envelope (/ba/(wa)). In the behavioral session, individuals listened to the same stimuli and judged whether they heard a /ba/ or /wa/. We hypothesized that a developmental shift in weighting strategies should be reflected in a change in the morphology of the N1-P2 AEP. In 6-year olds and adults, the N1-P2 amplitude at the vertex reflected a change in RFT but not in ART. In contrast, in the 4-5-year olds, the vertex N1-P2 did not show specificity to changes in ART or RFT. In all groups, the N1-P2 amplitude at channel C4 (right hemisphere) reflected a change in ART but not in RFT. Behaviorally, 6-year olds and adults predominately utilized RFT cues (classified /ba/(wa) as /ba/) during phonetic judgments, as opposed to 4-5-year olds which utilized both cues equally. Our findings suggest that both ART and RFT are encoded in the auditory cortex, but an N1-P2 shift toward the vertex following age 4-5 indicates a shift toward an adult-like weighting strategy, such that, to utilize RFT to a greater extent.
authors.affiliation: Department of Otolaryngology - Head & Neck Surgery, The Ohio State University, Columbus, OH 43212, USA.
authors.forename: Allen L
authors.initials: AL
authors.lastname: Carpenter
authors.forename: Antoine J
authors.initials: AJ
authors.lastname: Shahin
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D001303:Auditory Cortex / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003463:Cues; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010700:Phonetics; D013061:Speech Acoustics; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult