The effect of phonetic complexity on speaker race and sex identifications

Abstract

The purpose of this investigation was to determine the effect of phonetic complexity on speaker race and sex identifications. A total of 20 speakers, 10 white (five males and five females) and 10 black (five males and five females), recorded four kinds of auditory stimuli, representing four levels of phonetic complexity: (1) four isolated vowels (/i/, /u/, /æ/, and /α/); (2) four monosyllabic words ( light, rain, base, and side ); (3) four bisyllabic words ( sunlight, rainbow, baseball, and sidewalk ); and (4) four sentences ( the sunlight strikes raindrops in the air, the rainbow is a division of white light, he caught the baseball, and that sidewalk is broken ). A total of four master tapes were constructed, one for each kind of auditory stimulus. Twenty judges, 10 females and 10 males, participated in four listening sessions, one for each of the four master tapes. In each session they were asked to judge the race and sex of the speaker of each auditory stimulus as well as the confidence of each decision on a seven-point confidence rating scale. Results of their judgments indicate the following: (1) phonetic complexity had a significant effect on speaker race identifications, as evidenced by a progressive increase in listener accuracy from the simplest to the most complex auditory stimuli; (2) phonetic complexity did not appear to play a major role in speaker sex identifications, as evidenced by the lack of a regular trend in listener accuracy from simple to complex stimuli; (3) listener accuracy for sex judgments was always considerably greater than for race judgments at each of the four levels of phonetic complexity investigated; and (4) for each of the four kinds of auditory stimuli, listener accuracy for both race and sex judgments was better than that expected by chance guessing. Discussion of additional findings, including race and sex identifications based on differences in listener sex, speaker race and sex, and specific stimuli, as well as implications of these findings, are presented.