Autism, hypersensitivity to noise and sensory processing

Autism, hypersensitivity to noise and sensory processing

By Chrissy Hughes on 20th November 2015

My name is Stuart Neilson and I was diagnosed with Asperger syndrome in 2009 at the age of 45, after many years of ineffective psychiatric treatment. I have been involved in third-level teaching and research since 1987, including statistics, medical information systems and disablement (in Brunel University, London) and currently on autism studies at University College Cork. I have contributed to a number of books including guides to multiple sclerosis, motor neuron disease and Asperger syndrome / autism. My most recent book is on The Painted Lorries of Pakistan.

My personal blog is at and I review films and books about autism at Twitter: @StuartDNeilson

Autism, hypersensitivity to noise and sensory processing

Sensory issues and noise sensitivity have always been a part of the experience of autism (which includes Asperger syndrome), but only became a recognised part of the diagnosis with the fifth edition of the Diagnostic and Statistical Manual (DSM) of the American Psychiatric Association in 2013. The DSM-5 identifies “hyper- or hyporeactivity to sensory input or unusual interests in sensory aspects of the environment” including indifference, sensory-seeking and adverse responses to specific sounds, textures, smells and lights or movement. People with autism can be both over-sensitive (hyper) and under-sensitive (hypo), as well as either seeking out or avoiding sensory stimulation.

Children who experience noise as an unpleasant sensation, or even as physical pain, develop defensive reactions (such as covering their ears) and avoidant reactions (seeking only activities and places without excessive noise). People with autism frequently mention a dislike of percussive sounds, changing or unexpected sounds and specific, intense frequencies, such as strip-lighting and the hum from computer fans and fridges.

Social consequences of auditory hypersensitivity

The most immediately obvious consequence of defensive and avoidant reactions to unpleasant noise is a loss of social opportunity. Children are noisy, school is noisy, many workplaces are noisy and most socialising out of the home is centred around noise. Avoiding these experiences means avoiding elements of childhood play, education, employment and adult friendships that other people take for granted.

There are also less visible consequences of auditory hypersensitivity. Occupational therapists recognize difficulties with sensory experiences that may be termed “Sensory Processing Disorder” (SPD) or “Sensory Integration Dysfunction” (SID), implying a difficulty in the way the brain combines and processes raw sensory experience into meaningful information. People with autism may give the appearance of not paying attention, or be easily distracted, or appear to jump backwards and forwards within a conversation. Sensory integration can change the timing and sequence that people consciously perceive the world, so sensory overload can dramatically reduce the speed at which people with autism process conversation.

Attention deficit (ADD) and attention deficit hyperactivity (ADHD) are commonly diagnosed with autism and may be treated with medication. Many of the places where people have trouble paying attention are places full of unwelcome and distracting noises, and the same attention difficulties disappear in a home environment that is distraction-free.

People who are acutely sensitive to sensory overload occasionally experience sensory meltdowns, a severe example of the fight-or-flight response where the only safe course is to reduce or remove the sensory overload. We easily forgive children for behaviour that looks like (but is not) a temper tantrum, but we are not so forgiving with adults. A public sensory overload and meltdown is an acutely embarrassing and humiliating experience for adults with autism, especially if security guards or police officers are called to intervene. There are few quiet chill-out zones to take a break from the sensory backwash of modern shopping centres and other public spaces.

Ad-hoc solutions to living with hypersensitivity

Many people with autism develop ad-hoc strategies to filter or cut unpleasant noises. Fluffy ear-muffs and woolly hats are great for cutting out high-pitched sounds and overall noise, as long as the weather is not too hot. Hoods on clothing can improve directional hearing, amplifying noise ahead and cutting it from behind, which is good in a lecture. In-ear isolating earbuds and over-ear electronic noise-cancelling headphones are great for really noisy environments, such as aeroplanes and trains, but also busy streets and noisy neighbours — but can be tiring for extended wear.

Whilst these ad-hoc solutions all work to a degree, they also have downsides of being uncomfortable for long wear, of standing out in some circumstances and of failing to develop noise-tolerance skills. A hoodie might help tremendously in hearing the teacher in class, but the teacher might not approve. Fluffy ear-muffs look out of place in a nightclub. Security checks during travel (when a stressed adult may most need sensory relief) are particularly intolerant of ‘unusual’ behaviours.

Technological solutions and an “un-hearing” aid

Many music players, video players and televisions routinely incorporate amazing functionality to modify the experience of sound. The most basic devices have some form of equalizer, allowing the listener to alter the balance between bass, mid and high frequencies, affecting the intelligibility of speech. Many also have simple noise limiters (setting a maximum volume) or more sound compressors, which reduce the loudest noises and increase the quietest — this might be called “night mode”. Someone whose enjoyment is reduced by particular frequencies or types of noise, or by unexpected loud noises, can easily modify the experience of watching a blockbuster film at home.

It would be great to take some of this technology into environments that people with autism find hard — public spaces with the high-pitched squeal of low-energy lights, the hum of electric motors, car engines, ambulance sirens and the clatter of cutlery and crockery. One possibility is a reverse hearing-aid, an “un-hearing aid”, that takes the sound of the real world, filters out the noise elements that a specific individual dislikes and feeds it at a comfortable level through electronic noise-cancelling headphones or passive noise-isolating earbuds. It is easy to set up processing like this at home using a laptop, a guitar effects rig or music studio hardware — a workable chain is a noise filter (to cut the annoying background low-level hiss and hum of life), an equalizer (to cut selected frequencies) and a compressor (for “night mode” style reduction in unexpected loud noise). It is also easy to test an effect chain on pre-recorded audio.

It is not possible to take mains-powered music studio equipment into most public spaces, and even a laptop would be quite limiting. Anything that resembles recording equipment is, of course, not advisable in a cinema or music venue. Software on a smartphone, perhaps a user-configurable modified hearing aid app, would provide a useful base to try out some of these ideas unobtrusively in real life public spaces.

The discussion — awareness and public awareness

It may be that a software or analogue electronic solution is not ideal — perhaps materials science could offer a battery-free solution, or perhaps acoustic filtering and reflection could be embedded in clothing.

Above all, no solution should encourage avoidant and defensive behaviour that further excludes autistic people from social settings. This discussion may open up possibilities to examine personal sensory discomfort, to become more aware of the settings and stimuli that cause sensory load, and to work towards modifying the environments we share. A dimmer-switch for environmental noise in an “unhearing aid” could open the opportunity to provide graded exposure therapy, or temporary refuge to head off sensory meltdowns.

Playing with technology and sharing the experience of sensory distraction is a productive way to raise awareness of sensory sensitivity and the impact that it has on people with autism.

There are somewhere between 26,000 (1 in 178) and 92,000 (1 in 50) people with autism spectrum disorder in Ireland, and millions worldwide. These sensory issues are also experienced by many other people.

Further reading on autistic sensitivity

National Autistic Society (NAS) has further information about the sensory world of autism, including a brief video illustrating the impact of sensory overload. The following books provide practical information about the autism spectrum and sensory issues:

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