Vocal stereotypy in children with autism: Structural characteristics, variability, and effects of auditory stimulation

Two experiments were conducted to examine (a) the relationship between the structural characteristics (i.e., bout duration, inter-response time [IRT], pitch, and energy) and overall duration of vocal stereotypy, and (b) the effects of auditory stimulation on the duration and temporal structure of the behavior. In the first experiment, we measured the structural characteristics of vocal stereotypy in five children with autism during five 30-min free-operant sessions. The results suggested that the structure of vocal stereotypy varied considerably within and across participants. Furthermore, the overall duration of vocal stereotypy was positively correlated with bout duration and negatively correlated with IRT. In the second experiment, reversal designs were used to examine the effects of noncontingent access to auditory stimulation (i.e., music) on the vocal stereotypy of three participants. Music decreased engagement in vocal stereotypy for two of the participants. The reductions were mostly associated with a considerable increase in IRT. The implications of the results are discussed in terms of measuring the structural characteristics of vocal stereotypy to identify more effective matched stimuli and using music to facilitate the implementation of other interventions. (C) 2011 Elsevier Ltd. All rights reserved.