The (C)APD Controversy
There are no universal diagnostic criteria
The American Speech-Language-Hearing Association (ASHA, 2005) and the American Academy of Audiology (AAA, 2010) stipulate that an APD diagnosis can be made on the basis of below-normal performance on any two tests from a large battery of auditory processing tests and without consideration of ear-specificity or severity. This means there is no uniformity across individuals receiving the same diagnosis of (C)APD.
The following criteria appear to be in current use internationally:
The American Speech-Language-Hearing Association (ASHA, 2005) and the American Academy of Audiology (AAA, 2010) stipulate that an APD diagnosis can be made on the basis of below-normal performance on any two tests from a large battery of auditory processing tests and without consideration of ear-specificity or severity. This means there is no uniformity across individuals receiving the same diagnosis of (C)APD.
The following criteria appear to be in current use internationally:
- Pass hearing screening at 15 dB for all frequencies between 250 and 8000 Hz in both ears
- Performance at or below 2 SD (Standard Deviations) below the mean in at least 2 validated auditory processing tests
- Presence of symptoms reported by the affected individual / their family / education environment; and / or presence of risk factors
- Nonverbal intelligence coefficient (IQ) >80
- Patient can understand and reliably follow instructions for the auditory processing tests and reliably perform the pre-testing training
“APD is a very grey area... and that is why a lot of Audiologists don't like assessing it.”
[- Anonymous NZ Audiologist]
Despite 60 years of research, international researchers still cannot agree on the definition, diagnosis, and treatment of (C)APD, and the question remains whether it is a valid disorder at all.
When held to account against the Sydenham-Guttentag criteria for validity as a clinical entity, (C)APD is not a valid diagnosis. This is because (C)APD does not possess an unambiguous definition; it does not represent a homogeneous patient group; it may or may not represent a perceived limitation by the patient; and it does not facilitate diagnosis and intervention. The conclusion follows that without a gold / reference standard for the diagnosis of (C)APD, there is no evidence for the presence and absence of (C)APD as a clinical disorder.
Concerns have also been raised regarding the fact that the behavioural auditory processing tests used to diagnose (C)APD are the same tests originally used to diagnose Central Auditory Nervous System (CANS) lesions and regarding the flawed assumption that the diagnostic accuracy of an index test for the detection of one disorder is relevant for the detection of a different disorder.
Additionally, the growing realisation exists that the presence of overlapping symptoms in children diagnosed with (C)APD, Language Disorder, ADHD and Dyslexia supports the idea that these diagnostic categories are associated with each other in clusters, groups, or on a spectrum rather than being differentially diagnosable with distinctly unique criteria and clear and separate underlying causes.
When held to account against the Sydenham-Guttentag criteria for validity as a clinical entity, (C)APD is not a valid diagnosis. This is because (C)APD does not possess an unambiguous definition; it does not represent a homogeneous patient group; it may or may not represent a perceived limitation by the patient; and it does not facilitate diagnosis and intervention. The conclusion follows that without a gold / reference standard for the diagnosis of (C)APD, there is no evidence for the presence and absence of (C)APD as a clinical disorder.
Concerns have also been raised regarding the fact that the behavioural auditory processing tests used to diagnose (C)APD are the same tests originally used to diagnose Central Auditory Nervous System (CANS) lesions and regarding the flawed assumption that the diagnostic accuracy of an index test for the detection of one disorder is relevant for the detection of a different disorder.
Additionally, the growing realisation exists that the presence of overlapping symptoms in children diagnosed with (C)APD, Language Disorder, ADHD and Dyslexia supports the idea that these diagnostic categories are associated with each other in clusters, groups, or on a spectrum rather than being differentially diagnosable with distinctly unique criteria and clear and separate underlying causes.
The interesting case of (C)APD versus 'Speech Recognition in Noise Disorder' ...
(C)APD has been inextricably linked to a speech-in-noise deficit (Keith, 1986, Jerger & Musiek, 2000). However, there is great inconsistency in the number of children diagnosed with (C)APD who indeed have measurable speech in noise deficits: Findings range from 26% of children diagnosed with (C)APD having measurable speech in noise deficits to no significant difference in speech recognition in noise ability between (C)APD and control groups. One study even found that the (C)APD group performed better on a speech in noise test than the control group. These findings suggest the need to invoke a diagnosis of (C)APD occurs when a legitimate clinical entity is not identified. Audiologist and researcher Vermiglio (2016) has called for reconceptualisation of the (C)APD construct into legitimate individual disorders / clinical entities (e.g.: amblyaudia, spatialised listening in noise disorder, temporal resolution disorder).
Our recommendation
Listening, literacy, and learning difficulties are most readily explained by poor attention, poor auditory memory, poor phonological awareness, or poor language comprehension skills - or a combination of these. We therefore recommend screening to rule out difficulties in any of these areas before deciding whether or not it would be appropriate to proceed with expensive APD assessment. Children with poor attention, poor auditory memory, poor phonological awareness or poor language comprehension skills need intervention that works directly on improving these skills.
We find that children are often inappropriately diagnosed with APD based on confused diagnostic criteria and / or the presence of difficulties in collateral areas that should have precluded APD assessment and diagnosis. We also find that when children are diagnosed with APD, Audiologists recommend training of discrete auditory skills; even when the research shows that increasing discrete auditory skills does not improve language, literacy and learning skills. Audiologists also recommend classroom amplification systems for children, even when the child does not have difficulty listening in background noise. Classroom amplification systems also do not improve language, literacy and learning skills, they just make it easier to hear the teacher's voice.
We find that children are often inappropriately diagnosed with APD based on confused diagnostic criteria and / or the presence of difficulties in collateral areas that should have precluded APD assessment and diagnosis. We also find that when children are diagnosed with APD, Audiologists recommend training of discrete auditory skills; even when the research shows that increasing discrete auditory skills does not improve language, literacy and learning skills. Audiologists also recommend classroom amplification systems for children, even when the child does not have difficulty listening in background noise. Classroom amplification systems also do not improve language, literacy and learning skills, they just make it easier to hear the teacher's voice.
