Behavioral responses in 7 to 9 month old infants to speech and non-speech stimuli

A comparison was made of the behavioral responses of 36 infants (18 M, 18 F) aged 7--9 mo, to natural speech, warbled tone of 3 kc/s. and a noise band of 2--4 kc/s. The intensity level for speech was significantly lower, and the number of responses for speech was significantly higher, than for the other two stimuli. Girls demonstrated a significantly lower mean threshold and a significantly higher number of responses than boys. The threshold means for all three stimuli were significantly lower and the number of responses were significantly higher for the R ear than for the L ear in girls, but not in boys. There was no difference in threshold means for speech between the L and the R ears for the whole population, but there was a significantly higher number of responses to speech stimuli by girls, but not for boys, in the R ear than in the L ear.