Auditory Processing Disorder (APD) in Children: Guide

Watch out for APD look-a-likes

There are other disorders that can present with similar ‘symptoms’ as APD.  The intervention required may however be different.  Differential diagnosis is thus crucial.

It is important to identify/rule out the following disorders:

Unilateral (one sided) hearing loss. 

This can occur after a medical condition such as mumps or can be present from birth.The affected ear can be a ‘dead ear’ (no plottable hearing on an audiogram) or there can be some degree of hearing.  Having asymmetrical hearing makes in harder to hear speech in noise and less favourable listening environments.  It is also harder to hear someone talking on the side of the hearing loss.

High frequency hearing loss 

If hearing screening is done at a limited range of frequencies (e.g. 250-4000Hz rather than the standard range of 250-8000Hz) it is possible to ‘miss’ a high frequency ‘ski slope’ hearing loss.  High frequency hearing loss, like APD, makes it harder to hear in less favourable listening environments.

Another consideration is extended high frequency audiometry (and up to 12,000Hz). This is not routinely available in most audiology practices but could be considered, where possible.  There is some evidence of hearing loss in frequencies above 8000Hz for children with a history of glue ear.

Minimal and mild hearing loss

This is where a child has pure tone thresholds and a pure tone average between 20 and 40 dBHL, (i.e. 15dBHL) in either one or both ears.  A child with undiagnosed mild hearing loss may cope reasonably well in a quiet one-to-one environment but will find challenging listening environments more difficult.  S/he will show fatigue due to listening effort, which can present as fluctuating or poor attention.  There is evidence that minimal and mild hearing loss is associated with language, reading, memory and speech-in-noise difficulties (Winiger, 2016).

Glue ear

Glue ear affects a child’s hearing, particularly in the low frequency range.  It typically results in a fluctuating mild hearing loss which affects how a child hears, particularly in less favourable listening environments.  As a result the child may hear sounds inconsistently, which may affect speech, language and literacy development.

Children with a history of glue ear are at higher risk for developing a Spatial Processing Disorder, which is a specific type of APD.  It refers to an inability to utilise the directional cues embedded in sound in order to separate the speech we want to hear from background noise.  It occurs when the brain’s normal auditory processing abilities are unable to selectively focus on sounds coming from one direction and suppress sounds coming from other directions.

CLICK HERE for more information about Spatial Processing Disorder

Auditory Neuropathy Spectrum Disorder (ANSD) 

ANSD is a hearing disorder in which a large part of the inner ear responds appropriately to sound, but that information is not efficiently transferred from the ear to the brain.

Children with ANSD are likely to have greater difficulty understanding speech and distinguishing one sound from another than a child with a similar level of hearing, especially when there is background noise.  The hearing in children with ANSD varies from normal hearing thresholds to profound deafness but typical features include: difficulty understanding speech 
in background noise, speech recognition that is worse than would be predicted by the child’s level of hearing, hearing that may change over time: it may improve as well as deteriorate and could fluctuate on a day to day basis and difficulty in hearing rapid changes in speech.  ANSD is diagnosed using the Auditory Brainstem Response test, cochlear microphonic testing and oto-acoustic emission testing.

CLICK HERE for more information about ANSD.

References

Winiger, A.M, Alexander, J.M, & Diefendorf, A.O. (2016). Minimal Hearing Loss: From a Failure-Based Approach to Evidence-Based Practice. American Journal of Audiology, 25, 232-245.