Six-month-old infants discriminate voicing on the basis of temporal envelope cues (L)

Abstract

Young deaf children using a cochlear implant develop speech abilities on the basis of speech temporal-envelope signals distributed over a limited number of frequency bands. A Headturn Preference Procedure was used to measure looking times in 6-month-old, normal-hearing infants during presentation of repeating or alternating sequences composed of different tokens of /aba/and /apa/ processed to retain envelope information below 64 Hz while degrading temporal fine structure cues. Infants attended longer to the alternating sequences, indicating that they perceive the voicing contrast on the basis of envelope cues alone in the absence of fine spectral and temporal structure information.

Vowel discrimination by hearing infants as a function of number of spectral channels

“…Our findings that 6-month-old infants with NH cannot discriminate vowels (/ti/-/ta/) with 16 channels oppose results from Bertoncini et al (2011), who reported 6-monthold infants with NH can discriminate consonant voicing (/aba/ vs /apa/) with 16 channels. Several factors could explain these divergent results.…”

“…Several factors could explain these divergent results. The studies used different methodologies to test infant discrimination: Visual habituation (this study) and a head-turn procedure (Bertoncini et al, 2011). Both methods rely on an infant's intrinsic interest in novel stimuli and are appropriate to assess speech discrimination in 6-month-old infants (Houston-Price and Nakai, 2004;Polka and Werker, 1994;Werker et al, 1998).…”

“…Only one study thus far explores the effect of spectral reduction on infant perception (Bertoncini et al, 2011). Bertoncini et al (2011) tested discrimination of consonant voicing (/aba/ vs /apa/) with 16 sinewave-vocoded channels in 20 6-month-old NH infants using a head-turn preference method that contrasts alternating and repeating stimuli. Seventy percent of infants looked longer during alternation vs repetition series, implying sensitivity to differences in envelope cues.…”

“…We tested 6-month-old infants to match the age of infants in Bertoncini et al (2011). Participants included 52 5-to 7-month-old infants (34 male, 18 female) recruited from the Dallas metropolitan area (Table I).…”

Perception of the pitch of unresolved harmonics by 3- and 7-month-old human infants

“…Recordings of the frequency-following response and the envelope following-response to amplitude-modulated pure tones in 1-month-olds suggest that temporal coding is functional at the level of the brainstem (Levi et al, 1995). Infants have also demonstrated the ability to perform discriminations that rely on temporal processing: When presented with processed speech syllables containing only envelope cues and degraded temporal fine structure, 6-month-olds discriminated a voicing contrast (Bertoncini et al, 2011). That both 3-and 7-month-olds can discriminate the pitch of harmonic complexes could indicate little cortical involvement in complex pitch perception given the differences in cortical organization across this age range.…”