Say What? – Understanding Auditory Processing Disorders

http://www.webmd.com/add-adhd/guide/adhd-symptomsHearing loss isn’t just about the ear’s ability to process sound and send the signal to the brain. How the central nervous system processes the sound is a large contributor to speech perception.  The central nervous system plays an active role in working memory, language, and attention.  Auditory Processing Disorders (APD) are also referred to as Central Auditory Processing Disorders (CAPD).  One can have “normal hearing” and yet present with difficulty managing auditory information that is heard.  APD refers simply to an auditory deficit and is not the result of or does not affect other higher-order cognitive disorders.

Other disorders can affect one’s ability to attend to speech or another sound stimulus and may not fall under the umbrella of APD.  Those with Attention Deficit/Hyperactivity Disorder (ADHD), for example, may have trouble understanding and remembering spoken messages because the attention deficit is hindering their ability to use the incoming stimuli.  Similarly, those with autism may have difficulty with word comprehension due to the higher-order deficit – not specifically in neural procession of auditory stimuli.  These are independent of and should not be confused with APD.

Though the official APD diagnosis comes from the Audiologist, per American Speech, Language and Hearing Association (ASHA).  But it takes a team of professionals (teachers, educational diagnosticians, speech pathologists, psychologists, and audiologists) to fully understand the scope of symptoms for optimal treatment.  For diagnosis, there are a number of audiologic tests to assess hearing abilities, repetition processing, and the physiologic responses of the auditory system to sound stimuli.  Many of these tests, however, require a person to have the mental capabilities of a seven year old for proper interpretation.

Treatment of APD varies tremendously on an individual basis but generally focuses us on three things: environmental accommodations (to improve the auditory signal over other environmental factors aid in better focusing the attention), compensatory strategies using other higher-order skills, therapy to correct the auditory deficit itself.  As previously stated, treatment success varies significantly on an individual basis.  Some children essentially “grow out” of it and do not experience the difficulty as they get older; others require extensive therapy and may never be fully “cured” from it but, with treatment, can learn to be active listeners rather than victims of APD.

 

Beth Headshot fixedThis article was a contribution by Beth Benites, AuD who works at Oro Valley Audiology and raising a beautiful family when not seeing patients.

1 Comment

  1. ▬▬►NO Diagnosis Of APD is Valid Until ANSD Has Been Conclusively Ruled OUT.

    Quoting Chuck Berlin¹
    “Other individuals ultimately identifi ed with ANSD often came to us with a misdiagnosis of central auditory processing disorder (CAPD).”

    Unlike (C)APD which is somewhat nebulous, auditory neuropathy spectrum disorder (until 2008 called auditory neuropathy/dys-synchrony²) has specific electrophysiologic and other objective signatures that identify the four lesion sites:
    1) Missing inner hair cells (IHC)
    2) Misfiring of the IHC-spiral ganglion (SG) synapse
    3) Neuropathy of the SG
    4) Neuropathy of the auditory nerve

    For a truly frightening simulation of what ANSD sounds like to the sufferer, please listen to this sequence of profound, severe, moderate, mild, and then no ANSD samples, verified with unilateral ANSD sufferers (window opens into your media player for the WMA file):
    http://www.kresgelab.com/Resources/AN_simulation.wma

    ▬▬►Thought Exercise:

    Step One: Listen to that simulation a few times, and then imagine your brain having to pick speech out of the unsynchronized static;

    Step Two: Now imagine seeing a patient report showing a CAPD diagnosis without ANSD being ruled out.

    Step Three: Try to contain your frustration, bordering on anger.

    Fortunately, the ANSD screening test is pretty simple³ — Measure the ipsi & contra acoustic (stapedial) reflex thresholds across the speech range, and if they are elevated (above 90dB HL), then ANSD is in play. Also, lack of OAE suppression is a hallmark of ANSD, so if you don’t have a clinical tympanometer then you can use your audiometer & OAE meter to screen.

    REFERENCES:
    1) Multi-site diagnosis and management of 260 patients with Auditory Neuropathy-Dys-synchrony (Auditory Neuropathy Spectrum Disorder), by Berlin, Hood, Morlet et al (2010)
    http://csd.cbcs.usf.edu/an/Berlin_ANSD.pdf

    2) Management of Individuals with Auditory Neuropathy Spectrum Disorder, by Charles Berlin PhD (2008; Lake Como Conference proceedings)
    http://www.scribd.com/doc/7843429/Berlin-Lake-Como-Paper-in-Color

    3) Interview with Charles Berlin, PhD: Auditory Neuropathy Spectrum Disorder, OAEs, ABR, and More
    http://www.audiology.org/news/Pages/20120809.aspx

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