Central Auditory Processing
An Auditory Processing Deficit is often reported among children, including those with learning problems and can be related to specific auditory-cognitive deficits or attention disorders, or they can also occur when the child has a history of early middle ear infections. An adult may experience an auditory processing delay, that may have gone unrecognized from childhood. The inability to manage speech may also be the result of ageing of the auditory system or other neurological weaknesses.
It is possible a person with auditory processing problems will exhibit some or all of these symptoms:-
- Difficulty understanding speech in the presence of background noise or competing speech.
- Seems to hear, but not understand what people say.
- Distractibility, inattentiveness and poor attention span.
- Difficulty understanding verbal directions, or getting them confused.
- Academic under-achievement and reading difficulties because of auditory-phonetic confusions.
- Difficulty determining the direction a sound is coming from.
If a child or adult has some, or even all, of these characteristics, it does not automatically mean he or she has a APD. There are other disorders with similar characteristics, as the ability to do most of the activities listed above (eg. reading) require more than just good auditory-based skills and a thorough assessment is needed to try to determine the presence of a APD.
Assessments for APD should, at least, include testing by a qualified audiologist experienced in the evaluation of APD and this information should be considered together with other observations, by parents and from the classroom.
Tests that are available to assist in the identification of APD should include an extensive history, a standard hearing test to exclude peripheral loss, and the assessment should aim to cover the important areas of auditory processing.
The following types of tests may be used in an APD evaluation, and more than one test session may be required for complete evaluation:
Temporal ordering – Where the child’s ability to detect subtle differences in sound is assessed, when timing features are needed.
Dichotic Listening – (Listening with both ears at once), where different signals are presented simultaneously or overlapping to each ear.
Binaural Interaction – Where the ability of both sides of the brain to communicate with each other is assessed.
Speech in Noise – (Figure/ground), where speech is presented with increasing levels of background noise. Spatial separation ability allows selective attention to sounds coming from one direction and the ability to suppress sounds from another direction for a normal hearing listener. If the listener can’t manage this, then listening for speech in noise will be difficult.
Degraded Speech – Where information available in speech is reduced. This may be speech that sounds “speeded up” or reverberant, filtered speech signal, or interrupting parts of the speech signal.
Auditory Memory – the ability of a listener to retain and repeat information presented in an auditory form, which can require immediate recall or when using the working memory – this is when the listener may need to remember what has been said after a short delay.
So that the tests can be interpreted accurately, it is important the child being tested is able to understand language and communicate with others, have normal to near-normal intelligence, and at least 7 years of age.
Management of CAPD
Training to improve listening skills are based on the development of strategies for enhancing abilities in areas of auditory deficit. Management will focus on use of such strategies to maximise existing listening skills and encourage the development of new skills. The rationale for attempting to improve a person’s auditory processing is based on the “neural plasticity” of the child’s maturing central nervous system. Appropriate stimulation appears to allow plasticity (continuing improvement in function) and help extend critical learning periods.
Auditory training is usually facilitated by a speech pathologist or teacher, together with support from a parent to practice the skills at home. Strategies can be taught to compensate for the auditory deficit, and for coping in daily life, such as developing listening skills and improving comprehension of spoken instructions.
Other aspects of successful management will include:
Environmental Modification: adapting the listening environment to minimise noise levels and make speech louder than the noise can improve the child’s ability to process auditory information. For an adult, this tactic is important in social or work situations and for children, in the classroom, minimizing the noisy environment will benefit all the class.
Direct intervention: using techniques to improve auditory discrimination, integration skills, and associative skills (where the listener learns to associate incoming sounds with other information according to the rules of language), as well as teaching specific language or academic skills.
Examples of direct intervention include training the child to hear differences in sounds or words, teaching the child to pick out sounds or words when there is background noise, or teaching the child to use rhythm and temporal (timing) cues in speech.