Sample Recording of Spontaneous Speech for Age-Related Changes to Spectral Voice Characteristics (Dilley et al., 2013)

Purpose As children mature, changes in voice spectral characteristics co-vary with changes in speech, language, and behavior. In this study, spectral characteristics were manipulated to alter the perceived ages of talkers' voices while leaving critical acoustic–prosodic correlates intact, to determine whether perceived age differences were associated with differences in judgments of prosodic, segmental, and talker attributes. Method Speech was modified by lowering formants and fundamental frequency, for 5-year-old children's utterances, or raising them, for adult caregivers' utterances. Next, participants differing in awareness of the manipulation (Experiment 1A) or amount of speech-language training (Experiment 1B) made judgments of prosodic, segmental, and talker attributes. Experiment 2 investigated the effects of spectral modification on intelligibility. Finally, in Experiment 3, trained analysts used formal prosody coding to assess prosodic characteristics of spectrally modified and unmodified speech. Results Differences in perceived age were associated with differences in ratings of speech rate, fluency, intelligibility, likeability, anxiety, cognitive impairment, and speech-language disorder/delay; effects of training and awareness of the manipulation on ratings were limited. There were no significant effects of the manipulation on intelligibility or formally coded prosody judgments. Conclusion Age-related voice characteristics can greatly affect judgments of speech and talker characteristics, raising cautionary notes for developmental research and clinical work.