Autism spectrum disorders (ASD) are characterized by persistent impairments in social communication and interaction, restricted and repetitive behavior. In the original description of autism by Kanner (1943) the presence of emotional impairments was already emphasized (self-absorbed, emotionally cold, distanced, and retracted). However, little research has been conducted focusing on auditory perception of vocal emotional cues, being the audio-visual comprehension most commonly explored instead. Similarly to faces, voices play an important role in social interaction contexts in which individuals with ASD show impairments. The aim of the current systematic review was to integrate evidence from behavioral and neurobiological studies for a more comprehensive understanding of voice processing abnormalities in ASD. Among different types of information that the human voice may provide, we hypothesize particular deficits with vocal affect information processing by individuals with ASD. The relationship between vocal stimuli impairments and disrupted Theory of Mind in Autism is discussed. Moreover, because ASD are characterized by deficits in social reciprocity, further discussion of the abnormal oxytocin system in individuals with ASD is performed as a possible biological marker for abnormal vocal affect information processing and social interaction skills in ASD population
