Vowel and Speaker Identification in Natural and Synthetic Speech

The study describes the results of a listening test in which subjects were required to identify both the vowel and the sex of the speaker. Ten monophthongal American English vowels were selected: /i I ε æ a u Λ 3/. These vowels were produced by a male speaker, a female speaker, and a child. Formant values were read from spectrograms made of these vowels and used for synthesizing the same 30 vowels on a Glace-Holmes synthesizer. A third set of vowels was generated synthetically using formant and fundamental frequency values reported by Peterson and Barney (1952). In this set, the fundamental frequency characteristic of male, female and children's voices was combined with male, female and children's formants. The set of 150 stimuli was presented to 60 listeners, who were asked to identify the speakers and vowels. Overall speaker identification scores were higher than overall vowel identification scores for both normal speakers and vowels synthesized from measurements; for the Peterson-Barney set, the scores were approximately the same. The highest overall correct score was 88.3%, obtained for the normal male speaker; the lowest correct score was 31.0%, obtained for children's vowels synthesized from measurements.