Sound Sensitivity: What Does It Really Mean?

Commentary by Stephen M. Edelson, Ph.D.

Although attention in the field of autism has recently been focused on sound sensitivity, only a handful of researchers have examined or commented on this phenomenon. Most of the reports in the literature have simply listed sound sensitivity as one of the many characteristics exhibited by autistic children. Common descriptions include covering one’s ears, running away from a sound source, crying, and in some cases, throwing severe temper tantrums. The book, The Sound of a Miracle, by Annabel Stehli brought to light the problem of sound sensitivity and called attention to how it may impede the maturation of some people afflicted with autism.

One question is: Do the reactions to certain sounds in one’s environment necessarily mean that the person is experiencing pain? Based on my research with Dr. Bernard Rimland, Director of the Autism Research Institute in San Diego, and discussions with many professionals as well as people with autism, I feel that some individuals may experience pain; but in others, sounds are simply heard too loudly and may cause a fear response.

Painful hearing: Many adults with painful hearing have described certain sounds as “hitting a nerve” or cutting into their ear.” Some therapists who work with self-injurious autistic individuals feel that severe ear/head banging may be a reaction to painful sounds in the environment.

Although some people may display a physical reaction to sounds, others may react to painful sounds by ‘tuning out’ or ‘ignoring’ the sounds. This may be why autistic children are often described as ‘living in a shell’ and why many parents suspect their child of being deaf. If some, or possible many, sounds are perceived as painful, a child may revert to focusing his/her attention inward rather than outward. We do not know why some individuals have painful hearing. Interestingly, low levels of magnesium, an essential mineral, have been associated with sound sensitivity. We know that many autistic children respond quite well to vitamin B6 and magnesium. Furthermore, researchers have found that damage to the brainstem may lead to sound sensitivity.

Hearing too well: Another form of hypersensitivity is hyperacuity–hearing sounds too well. That is, sounds are not perceived as painful; but rather, they are perceived too loudly. I have heard many reports from parents who claim their child can hear sirens or hear airplanes in the distance before other people can hear them. I have also witnessed this phenomenon.Two other possible reasons for hearing too well is the brainstem’s inability to provide inhibition within the auditory pathway (see article describing Collett et al.’s 1993 study in The Sound Connection, Vol. 2, No. 1) and over-amplification of bilateral input (see article describing Woodward’s 1994 study in The Sound Connection, Vol. 2, No. 2).

Another aspect of hearing too well may be an emotional fear response to certain sounds. Annabel Stehli’s daughter, Georgiana, described herself as having ‘bionic’ hearing. It is important to mention that she had many fears associated with sounds. She described rain as sounding like machine gun fire. She could hear water rushing through pipes in the wall, and she was scared that the pipes would burst through the walls and hurt her. After receiving auditory integration training from Dr. Guy Berard, she no longer feared these sounds because she could no longer hear the water rushing through the pipes.There has been some speculation on a possible link between hypersensitive hearing, fear, and a part of the limbic system–the amygdala. Recent brain autopsies of autistic individuals, conducted by Dr. Margaret Bauman and her associates at Harvard Medical School, indicate that some neurons in the amygdala are abnormal and may not be working properly. The amygdala is responsible for many functions, including emotions and fear. Interestingly, there are auditory pathways connected to the amygdala; and researchers, such as Joseph E. LeDoux at New York State University, have found that these pathways are responsible for fear conditioning to sounds. This raises the question: Does AIT stimulate the amygdala in some way which reduces fear to sounds?

It is important that researchers attempt to separate these two possible types of sound sensitivity. They may involve different brain structures and imply different treatment strategies.

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This article appeared in a previous issue of The Sound Connection, 1995, Vol. 2, No. 3, page 2.

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