Many children on the spectrum are hypersensitive or feel over-stimulated to sounds, touch, taste, movements, smells, etc. As in the case of sensitivity to sound, you may notice children on the autism spectrum who place their hands over their ears. This was my son. He always placed his hands on his ears as if he was hearing someone screeching the chalkboard with their fingernails. (Aaah!) It wasn't all sounds but certain sounds. For instance, he couldn't listen to soft music played in an elevator. He would say, "It's too loud." He hated the bell schedule at school and didn't enjoy listening to the fans cheering at his brother's soccer game. He could however listen to cars driving down the freeway or music played in the car. Whether it was loud or soft, hearing was definitely an issue for my son. To ease his frustration and over-sensitivity, I placed headphones on his ears to lessen the sounds. I also arranged it with the teacher to have Noah place cotton in his ears at certain times of the day (to correspond with the bell schedule).
Over-stimulation, also known as sensory overload, is painful for the autistic child. It is important to identify the triggers to prevent a "meltdown" or an "outburst" from occuring.
To learn more about over-stimulation or sensory overload, I have written the following articles
http://autistic-child-parenting.suite101.com/article.cfm/autism--when-a-child-feels-over-stimulated
http://www.associatedcontent.com/article/5734754/autism_and_oversensitivity.html?cat=25
