One of the earliest signs of ASD is a delay in speech development. These delays can be in their ability to produce language, process and comprehend language, or both. Some children with ASD are thought not to have the desire to communicate. This, coupled with the social challenges faced by those with ASD, often hides any impairment in producing language. Additionally, attention issues and a lack of response to vocal stimuli can hide impairments in the child's ability to process and comprehend language. However, it is important to note that while high rates of language disorders and speech delays have been observed in children with ASD, not all those with ASD experience speech delays nor do all individuals with speech delays have ASD.