Reading #3 – neurological differences in sound processing

Auditory Processing in High-Functioning Adolescents with Autism Spectrum Disorder (DePape et all: 2012)

This was a ‘write-up’ of six separate tests conducted on groups of teenagers, some on the autistic spectrum, some with typical neurology.

They looked at the following:

  • The ability to filter out sounds in noisy environments – ASD (autistic spectrum disorder) people needed a higher speech to noise ratio when picking speech out when there is a second speaker than did the neurotypical (NT) group.
  • Whether people with ASD at the age of 1 year could discriminate between speech sounds in their native language when compared to foreign sounds as could the NT peers.  Typically, by one year, a child has already pruned synapses to allow them to discriminate the language spoken by primary carers but the researchers found this to be a less developed process in children with ASD.
  • Whether ASD individuals were less fazed by being shown faces making sounds other than those they were synced up with as they listened than were the NT group.  They were.
  • Whether ASD people are more likely to have absolute pitch (they are).  This is a rare and useful musical ability but also shows that sound processing is more absolute and less contextual for ASD individuals, which has implications for communication in a speech-dominated world.
  • Whether ASD individuals were slower to develop the discrimination of Western music-specific meters (regular, simple-time patterns) in infancy.  Essentially, they found that ASD people retained the ability to hear rhythm in a more absolute way that is less governed by the kind of music they hear where they live, beyond the age where NT peers have pruned their synapses to pick up on native rhythms and meters.
  • They did the same with harmony as they did with the Western rhythms they looked at in test 5 – did ASD individuals retain the ability to hear harmony without a bias to the music that their culture saturated them with for longer?  In this one, there was no big difference between the ASD subjects reactions and the control groups.

This research was clearly geared towards the hypothesis that the neural ‘roads’ that sound travels along and the way sound is organised and interpreted by the brain are different in autistic people and that this affects spoken communication.  However, I found it interesting to note that while the tests seemed to show that it was harder for autistic people to train their brains to hone in on the ‘right’ sounds to be sociable, it could be looked at from the other direction too: what listening benefits does this neural difference bring?

We have discussed in our electroacoustic music sessions Pierre Schaeffer’s notion of reduced listening, in which an audient attempts to detach a sound from its context, meaning, origin or connotations and hear only its sonic properties.  (Schaeffer, 1967) Could I, for example, manage to hear a dentist’s drill, gun shot or moan of pleasure without responding to my knowledge of what makes that sound, and only hear what is in the noise?  I am interested in the concepts of referential versus abstract sound, how much each has respectively on our experience as listeners, and how much we would find them to overlap.

(As an aside, it was also mentioned in lectures that Pythagoras liked to teach from behind a screen.  His theory was that his audience would concentrate better on his words if they were not distracted by his face and body language.  My autistic 8-year-old gets terribly distracted by people’s faces when they speak to him and will often look away in order to hear, whereas I would say that it is more typical for people to find that information is added by the non-verbal parts of communication.  To ‘listen’ to someone’s animated face or body language along with the words can make information easier to absorb and more memorable for me.  I wonder if Pythagoras himself was on the autistic spectrum?)

This research seems to suggest that autistic people ought to be able to practise reduced listening more readily and effectively than neurotypicals, as the neural road along which an autistic’s sound processing travels lends itself better to pure experience of sound than it does to picking out the social (or maybe the referential) meaning within the sound.

DEPAPE, A.-M.R., HALL, G.B.C., TILLMANN, B., TRAINOR, L.J. (2012) Auditory Processing in High-Functioning Adolescents with Autism Spectrum Disorder. PLOS ONE 7, e44084. doi:10.1371/journal.pone.0044084
SCHAEFFER, P. (1967) Traité des objets musicaux. Paris: Seuil

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