Synthetic and Natural Speech Preferences of Male and Female Listeners in Four Age Groups

The purpose of this investigation was to examine the preferences of listeners of both sexes in four age groups with regard to natural and computer-generated synthetic speech in six different contexts. The subjects (listeners) for this study included 5 males and 5 females in each of four age groups (6–8 year olds, 10–12 year olds, adolescents, and adults). The listeners rated their preferences for 11 different voices (four natural and seven synthetic) on a 5-point Likert scale. Their preferences were rated for six communication contexts dependent on the potential user of the voice (adult male, adult female, child male, child female, computer, and self). The data were analyzed separately for each of the six communication contexts. In general, female listeners across the age range indicated that only natural female voices (adult or child) were acceptable alternatives to their own speech, thus rejecting the natural male voices as well as the synthetic voices. Male listeners appeared to be somewhat more flexible in terms of gender-appropriateness for themselves and other adult men, but selected female-sounding voices for women and female children. Children preferred to have computers produce synthesized speech, while adults preferred computers with more natural-sounding voices. The results of this investigation raise a number of issues related to the combined effects of age and gender-appropriateness of natural and synthetic speech. These are discussed in terms of their implications for the future development of synthetic speech technology used in communication devices.