||Perception of speech modulation cues by 6-month-old infants
Purpose: The capacity of 6-month-old infants to discriminate
a voicing contrast (/aba /–/apa/) on the basis of amplitude
modulation (AM) cues and frequency modulation (FM) cues
Method: Several vocoded speech conditions were designed
to either degrade FM cues in 4 or 32 bands or degrade AM in
32 bands. Infants were familiarized to the vocoded stimuli for
a period of either 1 or 2 min. Vocoded speech discrimination
was assessed using the head-turn preference procedure.
Results: Infants discriminated /aba/ from /apa/ in each
condition; however, familiarization time was found to influence
strongly infants’ responses (i.e., their preference for novel vs.
Conclusions: Six-month-old infants do not require FM cues
and can use the slowest (< 16 Hz) AM cues to discriminate
voicing. Moreover, 6-month-old infants can use AM cues
extracted from only 4 broad-frequency bands to discriminate