Lauren B. Adamson, Roger Bakeman, Katharine Suma, Diana L. Robins

This study documents the early adverse effects of autism spectrum disorder (ASD) on auditory joint engagement-the sharing of sounds during interactions. A total of 141 toddlers (49 typically developing [TD], 46 with ASD, and 46 with non-ASD developmental disorders [DD]; average age 22.6 months) were observed during a semi-naturalistic play session with a parent. Reactions to four types of sounds-speech about the child, instrumental music, animal calls, and mechanical noises-were observed before and as parents tried to scaffold joint engagement with the sound. Toddlers with ASD usually appeared aware of a new sound, often alerting to and orienting toward it. But compared to TD toddlers and toddlers with DD, they alerted and oriented less often to speech, a difference not found with the other sounds. Furthermore, toddlers with ASD were far less likely to spontaneously try to share the sound with the parents and to engage with the parent and the sound when parents tried to share it with them. These findings reveal how ASD can have significant effects on shared experiences with nonvisible targets in the environment that attract toddlers' attention. Future studies should address the association between auditory joint engagement difficulties and variations in multimodal joint engagement, sensory profiles, and ASD severity and the reciprocal influence over time of auditory joint engagement experience and language development. LAY SUMMARY: Like most toddlers, toddlers with autism spectrum disorder often alert when they hear sounds like a cat's meow or a train's rumble. But they are less likely to alert when they hear their own name, and they are far less likely to share new sounds with their parents. These findings raise important questions about how toddlers with autism spectrum disorder experience their everyday auditory world, including how they share it with parents who can enrich this experience.