Auditory Processing Disorder (APD) 


​“APD is a very grey area... and that is why a lot of Audiologists don't like assessing it.”
[- Anonymous NZ Audiologist]
(Central) Auditory Processing Disorder (C)APD is an umbrella term used for a variety of disorders involving poor perceptual processing of auditory information by the central auditory nervous system.  ​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.  
 
​The Role of the Audiologist in diagnosing APD
ASHA's Technical Report (2005) states:  "Although abilities such as phonological awareness, attention to and memory for auditory information, auditory synthesis, comprehension and interpretation of auditory presented information, and similar skills may be reliant on or associated with intact auditory function, they are considered higher order cognitive communicative and / or language related functions, and thus are not included in the definition of (C)APD".  ​

This means that a (C)APD diagnosis should not be made on the basis of poor phonological awareness, poor memory, poor comprehension, etc.  In fact, Audiologists must ensure that a child's performance on behavioural auditory processing tests is not affected by co-occurring difficulties in any of the other collateral areas identified as underpinning a person's listening skills: their phonemic, linguistic and cognitive processing skills.

ASHA's Report goes on to advise that when there is suspicion of speech or language impairment, or intellectual, psychological, or other deficits, referral to the appropriate professional(s) should precede (C)AP testing to ensure accurate interpretation of results.  And in some cases, comorbid diagnoses will necessarily preclude (C)AP testing.

Speechie's Language & Listening for Learning Assessment is designed specifically to rule out deficits in collateral areas that might readily explain a child's difficulties before proceeding with (C)APD assessment.

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​The Processing Continuum

Processing of auditorily presented information involves a continuum of skills:

Auditory processing skills (assessed by the Audiologist)
  • Intact peripheral auditory system to perceive and receive acoustic stimulus
  • Intact Central Auditory Nervous System (CANS) to transmit acoustic signal through the brain to the upper cortex

Acoustic / phonemic processing skills (assessed by the Speech-Language Therapist)
  • Phonemic knowledge to discriminate / recognise sounds and words
 
Language processing skills (assessed by the Speech-Language Therapist)
  • Linguistic knowledge to discriminate / recognise the meaning of words / messages
 
Cognitive processing skills (assessed by the Speech-Language Therapist and / or Psychologist) 
  • Executive function skills to pay attention to the acoustic stimulus and to organise and execute a behavioural response
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