Wednesday, July 29, 2015

Your Audiology Tutorial, Auditory Processing, Part II

NOTE: Part One was posted in November 2010.  Um, sorry for the delay...

Recently I was the substitute teacher for a graduate class of Speech Language Pathology students.  The topic for the session was auditory processing, which has been defined a few ways:

"A deficiency in one or more of the auditory behaviors.  (An individual with an auditory processing disorder) is unable to attend to, discriminate, recognize, or understand auditory information and therefore has trouble making sense out of what is heard" (Yellin, 2004).


"Difficulties in the perceptual processing of auditory information in the central nervous system, and in the neurobiologic activity that underlies those processes" (ASHA APD Working Group, 2004)

In the earlier entry I began to list the sub-tests typical for an APD battery.  Continuing.....

-Staggered Spondaic Word Test (SSW): a dichotic (different signals simultaneously to both ears) listening test with bi-syllabic words presented partially overlapping in time, one to each ear.   The SSW is designed to assess auditory integration and the brain's ability to handle a more challenging environment for word understanding.  It considers "order effect", omissions, substitutions, and more in its highly complex scoring system.

-Phonemic Synthesis: an evaluation of the smallest units comprising a word (phoneme) in terms of the patient's awareness of them and the ability to fuse two or more together. Such skills are critical for reading.  The test requires the patient to respond with a word after hearing stimuli that consists of a set of phonemes separated by one second intervals.

-Auditory Continuous Performance Test (ACLT): Assessment of a patient's attention.  He or she is asked to respond when a target word (one version uses "dog") is announced among a list of "distractor" words.  The test is lengthy and almost becomes hypnotic for some participants.  It can be easy to lose track, especially for those diagnosed with ADD or ADHD.  An "impulsivity" error occurs if the patient responds to something other than the target.

The SCAN (Screening Test for Auditory Processing Disorders) is also sometimes implemented.  With versions for both children and adults, the SCAN is made up of several sub-tests including competing words/sentences, filtered words (distorted), and figure ground (identifying messages in the presence of competing noise). Some clinics may only use this set of tests for their evaluation.

Additionally, the Token Test can assess auditory comprehension skills in its evaluation of the patient's responses to verbal commands that become more and more complex.  A set of plastic colored tiles of various shapes are used and the tester will begin with something like "point to the blue circle" and progress to "place the blue circle on the orange square..." and so forth.

Treating an auditory processing disorder usually involves a modification of the learning/communication environment. Distance and background noise are factors that affect communication.  The most common strategy: preferential seating in the classroom.  Placing sound absorbing materials such as stuffed animals or even tennis balls can help.  Acoustic tiles are recommended.  Managing auditory overload is key. Assistive technology can improve the SNR (signal-to-noise ratio) in the room.  An FM system - devices worn by both student and teacher for wireless communication- is commonly used.

Audiological approaches involve attempts to strengthen a patient's localization skills, sequencing and memory, phonemic synthesis, the ability to recognize speech in noise (noise desensitization), and multi-modal integration.  Compensatory strategies can include the rephrasing of words, written and verbal assignments, and "chunking" - the breaking down of long messages or lists into smaller components and grouping concepts or objects together.  Computer programs like Fast Forward and Interactive Metronome have documented results in assisting with treating APDs. 

Not every audiologist performs the APE battery due to time constraints, reimbursement difficulties, and sometimes even lack of interest.  Call around.  Most audio clinics/ENT offices know of someone to whom you can be referred if their provider does not conduct these evals.  Universities with an Au.D. program and the school board in your area are good sources.  
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