This post is in the Sensory Issues category

With the assistance of my psychologist I drew up my sensory profile based on standardised tests  (Dunn, Myles & Orr, 2002). It showed a number of elements which are likely to have an impact on my perceptions in conjunction with my cognitive strengths and weaknesses.  Several of these relate to hearing and auditory processing and are probably a factor in my music-making. It is important to note that each of these elements has a variable character, that is, they are not equally present all the time, but surface in different combinations and strengths.  It is also important to note that elements of this profile are not unique to autism or Asperger’s – everyone has a profile of sensory strengths and weaknesses.  It is the degree of imbalance that may have the impact.

Visual, tactile and aural senses strongly local and fragmented: refers to the ability to automatically or spontaneously to assign detail to its gestalt. It is related to hypersensibility, which is commonly found in individuals on the autistic spectrum  (Dunn et al., 2002; Gomes, Pedroso & Wagner, 2008). I tend to see and hear in small chunks and notice details and patterns of details rather than complete objects.  In the visual realm this means I am more likely to notice a number plate than the colour of a car, and navigate by a large number of closer landmarks rather than a general sense of direction. It also may reduce my susceptibility to optical illusions (Gepner & Mestre, 2002; Happé, 1996; Walter, Dassonville, & Bochsler, 2009) –  as I tend to see things as they are.  In the audio realm I tend to process spoken words independently rather than the gist or Gestalt of a sentence. This can lead to a rather literal interpretation of speech and, in combination with a “one at a time” sensory system, a tendency to miss irony, sarcasm or downright lies. On the other hand, I hear “inside’ music, being strongly aware of the notes, tones, instrumentation, envelope etc of the individual parts of sound.  In this way I can easily analyse the sonic content and understand how it is made.

In times of stress, I begin to experience my sonic world “fracturing” and breaking up, the sounds may process in the wrong order and different frequency bands “come in” at different times.  The first time I heard a granular synthesis system processing grains of a couple of hundred milliseconds I instantly recognised the effect, and loved the ability to control something which, while mercifully rare, is a very disturbing experience when it happens spontaneously.

Visual and Aural Filtering: is the prioritising system that assigns importance of incoming data.  An analogy can be drawn to time management skills, where a “to do list” can be sorted into tasks that are important and those that are urgent and then assigned priority.  In a sensory system, “urgent” equates to “close” and “important” equates to the likely effect on one’s person.  In recording practice we use techniques such as polar patterns, baffles and proximity to “focus the attention” of the microphone on the source.  The ear itself, however is more like an omni system – it takes in everything and the brain sorts it out. The ear is very sensitive to sound and includes physical and cognitive processes that protect the cochleal hair cells and increase their dynamic range sensitivity from around 50dB to 120dB  (Levitin, 2006, p. 68). This in combination with the ability to discern tiny changes in time of arrival and phase relationships between the two ears offers an enormous amount of information to the brain.

A well functioning filtering system does the prioritising quickly and sub-consciously, but if the system is inefficient, conscious effort may be needed to decide what to pay attention to.  In the aural realm, if I am among a group of people, a train for instance, I tend not to filter other people’s conversations.  Instead I hear everything said by everyone.  Even if I am in a conversation with someone next to me, I still hear and process the words said by someone half a carriage away, and then have to consciously sort the relevant information. This does not happen all the time – it is an increased effect if I am stressed, for example if on a different train to my usual routine

Shutting down other senses when one is engaged; describes a process whereby one sense is fully engaged or overloaded, so the others stop functioning or feed inaccurate information.  For example, a lot of flashing lights or glare can drastically reduce the amount of audio information I can process.  In the everyday world, I cannot process facial expression and speech at the the same time.  If I watch the face, I don’t remember or understand what is said, so I tend to gaze at something non-human.

Difficulty interpreting visual, aural and tactile input; indicates that there is a slight delay in processing incoming information, particularly if several senses are involved, and some information is discarded.

Vestibular and aural overload: The vestibular system governs the individual’s knowledge of their position in space, via balance, head and limb position, pressure on the feet, visual reference points and auditory spatial cueing through time of arrival and frequency differences between the two ears.  The only real-life impact this has on me is a lack of enjoyment of things such as carnival rides, and a general need to keep my feet on the ground.  There is a strong link between the vestibular and aural systems however.

Aural overload for me is complex and contextual.  In a musical context this mainly concerns volume and distortion.  I expect music to be of a reasonable volume and I can handle volume if I’m expecting it, loud music is not a problem.  However if the dynamic is un-naturally effected, by an over enthusiastic or unskilled compression I will become disoriented and nauseous.  I went back over comments on student work from the past couple of years and found several entries along the lines of “the master buss compression is over-used and too slow and made me feel sea-sick”.  The same physical effect is induced by certain types of distortion, particularly in digital systems.

Fascination and perseveration on aural and tactile: Fascination with sounds and textures is of course not uncommon, and can be very useful.  Problems arise if perseveration – the persistent continuation of sensation and thought after the stimulus is removed – becomes prolonged or results in the shut-down of other senses, or blocking of further sensory input.

Delayed processing of bodily sensation: My son likes to refer to this as the “dinosaur effect” after the (now largely discredited) idea that if you step on a dinosaur’s tail, the pain takes a while to travel through the nervous system to his brain, giving you time to run away.  The phenomenon is not so much related to skin tactility as internal sensations, particularly those related to autonomic systems such as the stomach and core muscles.  This means that some individuals do not associate body sensation with emotion because they are not perceived at the emotional moment. An typical example of this might be someone will go through a stressful situation such as assisting an accident victim, and later notice the strain on their body, even going into shock.  The symptoms had previously been masked by adrenaline.  Where processing is delayed, this occurrence is common in everyday life and requires a conscious effort to identify the source of the sensations.  “I have a tension in my stomach and upper body, my breathing is shallow and my hands are trembling.  These are signs of anxiety. What happened in the last couple of hours that might have triggered that?” or “My legs are weak and I’m dizzy if I stand up. Does my stomach have any feelings? No, but I haven’t eaten for six hours, maybe I’m hungry.” This latter example can lead to eating problems, as the identifiable feeling of hunger may not may not occur until after the person eats, therefor encouraging them to eat more.

Auditory and olfactory associated memory triggers: Most people’s memories are triggered by visual stimuli.  This may explain the proliferation of the digital camera, as seeing the photographs brings back detailed memories of the events that they represent. Others are more strongly triggered by sounds – a voice will trigger a memory where a face will not.  For example if you meet someone you have not seen in twenty years you may not recognise them or recall any details of your time together until they speak. Olfactory triggers may be closely linked to emotions, for example the smell of a familiar building will trigger memory of the feelings you had when you were last there.

In my case visual stimuli such as photographs don’t really do it for me unless they are very focussed. I discuss this issue in the section on using images within this document, but sounds do.

Related to this aspect of senses is the ability to recall memory.   Most people have strong recollection of faces.  Some people recall mental images of inanimate objects much more easily than images of people. Others, such as myself have very strong aural or olfactory recall.  I can bring back a particular sound or smell very easily, examine it, pull it apart and analyse it, but I have trouble recalling the faces of my wife and children and become anxious if I am separated and have to meet them, at the shopping centre for example.  “I can’t recall their faces so will I recognise them?”

Thinking in auditory and tactile pictures: Many autistic individuals report “thinking in pictures” (Chamak, Bonniau, Jaunay & Cohen, 2008; Grandin, 2006; Grandin, 2009) and this is recognised as one mode of non-linguistic thought.  But it is important to note that these “pictures” do not have to be visual.  A “picture” can be a sonic or tactile one, still not involving language, and serve the same problem solving, learning or understanding functions.  It is rather hard to explain – this is after-all a language based document.

Sensory sensitivities, anomalies and other issues are a constant source of stress to people with ASDs.  They impact upon every aspect of life in terms of distractions in day-to-day life, communicating and interacting.  In my own case the aural elements are of the most important consequence, in both positive and negative modes, but many people with heightened traits are impacted in their learning and work environments.

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