Effect of formant transition rate on the differentiation of synthesized child and adult (w) and (r) sounds.
The purpose of this research was to assess the perceptual effects of a range of second (F2) and third (F3) formant transition rates that occur naturally in the production of /w/ and /r/ by children and adults. Synthesized CV continua that varied in the second (F2) and third (F3) formant onset frequencies between values appropriate for /w/ and /r/ were used as stimuli. Subjects participated in four experimental conditions that involved changing the rate of transition of either F2 or F3 by varying the duration of the transition between the glide onset and an /eI/ vowel nucleus for child and adult stimuli. In each condition, the transition rates of the /w/-endpoint stimulus, the /r/-endpoint stimulus, and at least one of the midpoint stimuli were varied across values appropriate for /w/ and /r/. Mean ratings of the stimuli were compared to test the predictions that /w/ perception increases with increased F2 transition rate and increases with decreased F3 transition rate. The results were as follows: (a) one of the 10 comparisons for the child F2 stimuli was significant, but it involved a change opposite to the predicted direction; (b) four of the six comparisons for the child F3 stimuli were significant, but they involved changes opposite to the predicted direction; (c) 14 comparisons of adult F2 stimuli were significant, but 12 of these 14 comparisons involved changes opposite to the predicted direction; and (d) four of the six comparisons for the adult F3 stimuli were significant, but none of them involved changes in the predicted direction. Only one of all the comparisons involved a significant change in rating between the /w/ and /r/ categories.
D002648:Child; D002663:Child Language; D006801:Humans; D010700:Phonetics; D013060:Speech; D013061:Speech Acoustics; D013067:Speech Perception