Understanding early communication signals in autism: a study of the perception of infants' cry.

BACKGROUND

Previous studies have highlighted that episodes of crying of children with autistic disorder (AD) were perceived as inexplicable from their parents who could not identify causative factors. These results supported the view of AD as related to a problem of expressing and sharing emotions. Moreover, no evidence has been presented on which characteristics of a cry episode influence the adult perception. Aim of our research is to investigate how acoustical features of crying episodes modulate their perception of infants with ASD compared with infants with typical development (TD) and infants with developmental delay (DD).

METHODS

Two studies were employed. In study 1, we artificially modified structural parameters (fundamental frequency, duration of the pauses, waveform modulation) of a cry episode, and then 50 adults (parents and non-parents) were asked to judge the level of distress elicited. In study 2, acoustic analysis was applied to episodes of crying selected from retrospective home videos of 42 children with AD, TD and DD at 18 months.

RESULTS

The results showed that (1) differences in the fundamental frequency and in other structural parameters of the cry lead parents and non-parents to perceive an episode of crying as more aversive and (2) at 18 months of age, AD episodes of crying have higher fundamental frequency (f0).

CONCLUSION

Our findings offer support for the hypothesis that acoustic characteristics of episodes of crying of children with autism, especially higher fundamental frequencies, may account for mental states of uneasiness in the listener.