You may be surprised how many children with autistic disorder have hyper sensitivity and sensory issues.
Sometimes this manifests itsefl with extreme reactions to smell, touch, taste, warm/cold and sounds.
My son was particularly sensitive to loud noises and we found that using ear defenders helped him a great deal. Please don't get mixed up with headphones which can sometimes be useful in their own way. Ear defenders are designed to actually block sound out !
Yes, you do get some funny looks from people - however we would not have been able to get him into a public toilet without them. He was absolutely petrified of the noise of hand dryers and this helped us enormously.