Examining the Collateral Effects of Reducing Voice Level on Vocal Stereotypy and Functional Speech.

The current study examined the collateral effects of an antecedent intervention for decreasing speech volume on vocal stereotypy. After teaching the participant to use a conversational voice level by providing visual feedback from a decibel meter app, conversational voice levels were differentially reinforced in the presence of a green card. Differential effects in voice magnitude during a green-card condition and a no-card condition were demonstrated using an alternating-treatments design. Results showed a decrease in volume of speech during the green-card condition, an overall decrease in vocal stereotypy, and a decrease to zero levels in loud stereotypical vocalizations. The implications of these findings on the treatment of vocal stereotypy are discussed. © Association for Behavior Analysis International 2021.