THE ACOUSTIC BASIS OF PREFERENCES FOR INFANT-DIRECTED SINGING

Acoustic differences between infant-directed and noninfant-directed si nging were examined in 6 playsong and 4 lullaby pairs of recordings fr om Trainer (1996). Each mother had been recorded singing a song of her choice to her infant and singing the same song in the absence of her infant. For both playsongs and lullabies the tempo was slower, there w as relatively more energy at lower frequencies, inter-phrase pauses we re lengthened, and the pitch and jitter factor were higher in the infa nt-directed over infant-absent versions. Pitch variability was higher and the rhythm exaggerated (as measured by the relative duration of st ressed to unstressed syllables) in the infant-directed versions of pla ysongs but not lullabies. Many of these acoustic modifications likely attract infants' attention, and playsongs and lullabies likely communi cate different emotional messages.