Understood is a website that provides information and support to parents and those interested in helping kids who have learning differences and attention issues. I found this website through the National Center for Learning Disabilities which is one of the well know non-profits that helped create the website. One of the features of the website is called Through Your Child’s Eyes. Which gives the perspective of the child’s experience with their learning issues. Here is a great one describing Sensory Processing Disorder.
I have seen a child cover her ears and scream when she went into a gym filled with noisy kids. If you understood it is actually painful for the child to hear all the noise, it explains the behavior.
Sensory Processing Disorder does not just affect children with Autism. It can exist by itself or with other conditions like ADHD.