Vocal Pitch
From infancy through adulthood, autistic people tend to produce high within-person variability in vocal pitch and tones across the speech trajectory (DePape et al., 2012; Diehl et al., 2009; Nadig & Shaw, 2012; Paul et al., 2011), cries (Esposito et al., 2014, 2009; Sheinkopft et al., 2012), and amongst different cultural and lingual contexts (Bonneh et al., 2011; Filipe et al., 2014; Sharda et al., 2010). Thus autism affects the expression of acoustic qualities of speech such as stress and intonation, especially for A-SOD rather than A-NoSOD in childhood (Peppé et al., 2011). Among adults, A-SOD had lower vocal pitch range and understanding of vocabulary but speech more rhythmically aligned with its information structure than A-NoSOD (Sharda et al., 2010). This may suggest that A-SOD use more precise auditory processing to support music-like rhythm in speech. Autistic children show reduced processing of spoken language as a function of verbal abilities (Sharda et al., 2015), and heightened processing of song or musical abilities relative to their IQ (Bhatara et al., 2013), verbal skills (Lai et al., 2012), and experience (Depape et al., 2012). Paradoxically, A-SOD’s enhanced processing of acoustics of speech may interfere with processing speech’s meaning.