Influences of vowel duration on speaker-size estimation and discrimination

Several experimental studies have shown that the human auditory system has a mechanism for extracting speaker-size information, using sufficiently long sounds. This paper investigated influence of vowel duration on the processing for size extraction using short vowels. In a size estimation experiment, listeners subjectively estimated the size (height) of the speaker for isolated vowels. The results showed that listeners’ perception of speaker size was highly correlated with the factor of vocaltract length in all the tested durations (from 16 ms to 256 ms). In a size discrimination experiment, listeners were presented with two vowels scaled the vocal-tract length and were asked which vowel was perceived to be spoken by a smaller speaker. The results showed that the just-noticeable differences (JNDs) in speaker size were almost the same for the durations longer than 32 ms. However, the JNDs rose considerably for 16-ms duration. These observations of the experiments suggest that the auditory system can extract speaker-size information even for 16-ms vowels although the precision of size extraction would deteriorate when the duration becomes less than 32 ms.