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APD testing - recommendationsAs discussed under ‘APD tests and criteria’ referrals for APD evaluation from professionals are increasing, and parents are demanding appropriate services when they learn of the existence of APD on the Internet and other media sources. Many audiologists have understandably been cautious about including APD assessment in their clinical practices, given the controversy and lack of evidence surrounding APD assessment (Kraus and Anderson, 2016)
Based on current evidence the British Society of Audiology (BSA, 2018) offers the following advice:
- Engage with, educate and inform stakeholders (professionals, individuals with suspected APD, parents) and funders about APD.
- Determine and address the difficulties that a child is experiencing in real life (a detailed case history, validated questionnaires and professionals’ reports can be used to obtain a 360° view of a child).
- Understand the reported hearing difficulty against the background of a multi- or interdisciplinary assessment that considers aspects such as language, attention and memory.
- Recognise that audiological assessment for APD should not be done in isolation given that aspects such as language ability, attention and memory may affect test results. There are different multi- or interdisciplinary models that can be considered. For example, it is possible for the audiologist to request that other assessments, such as a speech and language assessment and educational psychology assessment, be done prior to referral for an APD assessment. Another approach is to have an interdisciplinary team all working together under one roof.
- Do an audiological work-up to rule out hearing loss, middle ear dysfunction and evaluate speech perception in quiet and noise first.
Separate left and right ear pure tone audiometry (250-8000Hz) and immittance testing (including reflexes) are necessary to rule out hearing impairment and middle ear problems, requiring medical and/or audiological intervention. There is some evidence that contralateral acoustic reflexes can be absent for some children with APD and that oto-acoustic emissions in the presence of contralateral broadband noise may have diagnostic value. Comparing speech perception (using tests with different levels of language complexity, e.g., digits, sentences, words) in quiet and noise can be helpful in determining the influence of both language and noise. For example, if a child can correctly repeat all types of stimuli in quiet but then struggles in noise that may suggest difficulty hearing in noise. Another child, however, may be unable to repeat sentences in quiet at an age-appropriate level, suggesting that language may also be playing a role.
The Listening in Spatialized Noise-Sentences test can be used to diagnose Spatial Processing Disorder (SPD). SPD is a specific type of APD where a child has a reduced ability to use spatial cues to hear in background noise. There is a higher reported prevalence in children with glue ear. Newer variations of this test include: the Listening in Spatialized Noise Universal test (which uses nonsense syllables common to most of the world’s languages, in a consonant-vowel-consonant-vowel format) and the Language-Independent Speech in Noise and Reverberation test (which also assesses the impact of reverberation and considers fluctuations in attention on performance)
Finally, if there is suspicion of Auditory Neuropathy Spectrum Disorder (ANSD) further appropriate tests can be done. 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.
- Make evidence-based decisions around administering and interpreting traditional tests of APD. Examples of the most commonly used tests are the dichotic digits test, the frequency pattern test, the duration pattern test, the masking level difference test and the gaps-in-noise test. Audiologists should only use tests that fulfil the criteria of functional specificity, reliability, validity, age-appropriateness, and standardisation, with a clear statement of diagnostic criteria used in reports.
- In children younger than 7 years of age, where traditional tests of APD are not possible, support should not be delayed. Appropriate and timely onward referral and management is important. Speech and language therapists are well placed to advise in these cases, given that APD often co-exists with speech, language, phonological awareness, attention, and memory difficulties.
- Recognise the complexity and current controversy surrounding APD. The BSA, along with an increasing number of audiologists worldwide, are proposing that one way forward could be that only those audiologists with further training and accreditation by a professional academy or society be allowed to diagnose APD.
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