Auditory Processing

Auditory processing (AP) is defined as “what we do with what we hear”.

It is a term used to describe how we use our hearing to make sense of the world.

The human brain uses the input from the five senses of hearing, vision, smell, touch and taste to process information. Individuals rely differently on each of these senses.

Our ears are exposed to sounds 24 hours a day. The sounds collected from the environment are transmitted from both ears all the way to the brain. Most sounds coming from the right ear go to the left side of the brain and vice-versa. The brain selects relevant sounds, processes and makes sense of the received information.

Auditory processing is not dependent on normal hearing. Individuals with a hearing loss may have good auditory processing skills provided the sounds are amplified to compensate for the loss by means of properly fitted hearing aids. On the other hand, sound deprivation caused by a non-treated hearing loss may lead to an auditory processing disorder.

The most known risk factors for an auditory processing disorder are:

- Prolonged episodes of ear infection (glue ear, otitis media)

- Birth distress or prematurity

- Craniofacial or external ear abnormalities

- Head trauma

- Cerebral vascular ischemia (stroke)

- Brain lesions

- Brain tumours

- Sound deprivation

There are however, a number of children diagnosed with auditory processing disorders where the original cause cannot be identified.

In adults the disorder is expected to increase with age or injuries to the central nervous system. Performance of the left ear tends to decrease at a greater rate than the right ear in what is called “right ear advantage”. Most right-handed individuals are found to rely more on the right ear for auditory processing.

Auditory processing disorders may lead to the following symptoms:

- Difficulties in understanding speech in adverse conditions such as in noisy environments.

- Difficulties in localising sounds.

- Difficulties in following verbal instructions.

- Intolerance to loud sounds.

- Attention deficit.

- Memory deficit.

- Learning difficulties such as spelling, writing and reading problems (dyslexia).

- Hyperactivity and behavioural problems in children.

To experience one or more of the above symptoms does not necessarily mean there is an auditory processing disorder that will affect your quality of life. If the problem is severe, however, it may affect children’s performance at school and adult’s social and working lives.

The aim of diagnosing an auditory processing disorder should not be to label the individual and justify an existing problem. It should rather be to identify strengths and weaknesses in the auditory processing skills, relate the weaknesses to the individual’s reported difficulties and to help in the management of the problem.

Auditory processing skills can be clinically tested by a qualified audiologist. The first step of the evaluation is a comprehensive hearing test to exclude the possibility of a peripheral hearing loss. This assessment involves a pure tone and speech audiogram, tympanometry, acoustic reflexes, otoacoustic emissions and auditory
evoked responses.

Subjective tests for auditory processing are performed using tests where the individual is required to listen and respond to a series of sounds, words and sentences presented through headphones at different levels of difficulties, such as with competing noise in the opposite ear and/or in the same ear, with distorted and filtered speech etc.

These tests can be reliably performed on children from seven years of age.

Objective electrophysiological tests are also used to assess auditory processing. These are measurements of the brain responses to sound performed by placing electrodes on the ear lobes and on the scalp. Different sounds are presented via headphones. This procedure can be performed in younger children provided there is some degree of cooperation.

Both subjective and objective test procedures are not invasive and do not cause any physical discomfort.

Everybody is different.

This universal rule also applies to sensory processing skills. Different individuals process information using different strategies and this may not necessarily be due to a “processing disorder”. Some situations may not provide an adequate environment for an individual’s “preferential” processing skills.

For example, a child with weak auditory processing skills who relies more on visual processing may not perform well in a school using phonics.

This situation may be improved by training the child to develop stronger auditory processing skills or by modifying the environment, for example by changing to another school with a different teaching method.

Audiological test results therefore aim at identifying the individual’s auditory processing skills, develop and strengthen the weaker skills by means of auditory training, and/or modifying the environment to adapt to the individual’s abilities.

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©2006, Celene McNeill