Wednesday, May 22, 2013

Auditory processing disorder (APD): Schisms and skirmishes

Spanish version of a schematic representation ...
Spanish version of a schematic representation of auditory signaling. (Photo credit: Wikipedia)
Survey of the controversies within Auditory Processing disorder, especially when using a SCAN-C, a common diagnostic test, with children who do not speak English well. 

In 2006, David
Moore, Director of the Medical Research Council’s Institute of Hearing Research
in Nottingham, created a stir when he published a paper arguing that APD
diagnosis should be based on performance on non-linguistic tests of auditory
perception. Moore’s concern was that tests such as SCAN-C, which use speech
stimuli, can’t distinguish an auditory problem from a language problem. I made
similar arguments in a blog post written last year. Consider the task of doing a speech perception test in a
foreign language: if you don’t know the language very well, then you may fail
the test because you are poor at distinguishing unfamiliar speech sounds or
recognising specific words. This wouldn’t mean you had an auditory disorder.


A recent paper by
Loo et al (2012) provided concrete evidence for this concern. They compared
multilingual and monolingual children on performance on an APD battery. All
children were schooled in English, but a high proportion spoke another language
at home.  The child’s language background
did not affect performance on non-linguistic APD tests, but had a significant
effect on most of the speech-based tests.


In 2006, David
Moore, Director of the Medical Research Council’s Institute of Hearing Research
in Nottingham, created a stir when he published a paper arguing that APD
diagnosis should be based on performance on non-linguistic tests of auditory
perception. Moore’s concern was that tests such as SCAN-C, which use speech
stimuli, can’t distinguish an auditory problem from a language problem. I made
similar arguments in a blog post written last year. Consider the task of doing a speech perception test in a
foreign language: if you don’t know the language very well, then you may fail
the test because you are poor at distinguishing unfamiliar speech sounds or
recognising specific words. This wouldn’t mean you had an auditory disorder.




A recent paper by
Loo et al (2012) provided concrete evidence for this concern. They compared
multilingual and monolingual children on performance on an APD battery. All
children were schooled in English, but a high proportion spoke another language
at home.  The child’s language background
did not affect performance on non-linguistic APD tests, but had a significant
effect on most of the speech-based tests.



Dillon and
Cameron (Australia) queried the usefulness of a general term such as APD, when
the reality was that there may be many different types of auditory difficulty,
each requiring its own specific test. They described their own work on ‘spatial
listening disorder’, arguing that this did relate to clinical presentation.


The most critical
of Moore et al’s arguments were Bellis and colleagues (USA). They implied that
a good clinician can get around the confound between language and auditory
assessments: “Additional controls in cases in which the possible presence of a
linguistic or memory confound exists may include assessing performance in the
non-manipulated condition (e.g. monaural versus dichotic, nonfiltered versus
filtered, etc.) to ensure that performance deficits seen on CAPD tests are due
to the acoustic manipulations rather than to lack of familiarity with the
language and/or significantly reduced memory skills.” Furthermore, according to
Bellis et al, the fact that speech tasks don’t correlate with non-speech tasks
is all the more reason for using speech tasks in an assessment, because “in
some cases central auditory processing deficits may only be revealed using
speech tasks”. 


http://albertochil.blogspot.com/2012/10/auditory-processing-disorder-apd.html
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