Friday, October 19, 2012

Spothlight on Audiology: (Central) Auditory Processing Disorder!

You may have heard of Central Auditory Processing Disorder (CAPD) or Auditory Processing Disorder (APD) in the past.  These terms are used interchangeably and refer to the same skill set.

The following information was adapted from the ASHA website  (American-Speech-Language Hearing Association).
Please click on the link above for more detailed information.

What is (Central) Auditory Processing [(C)AP]? 
ASHA's (The American-Speech and Language Association) definition: “(Central) Auditory Processing [(C)AP] refers to the efficiency and effectiveness by which the central nervous system (CNS) utilizes auditory information”. 
AP includes skills such as:
·         “sound localization and lateralization;
·         auditory discrimination;
·         auditory pattern recognition;
·         temporal aspects of audition, including temporal integration, temporal discrimination (e.g., temporal gap detection), temporal ordering, and temporal masking;
·         auditory performance in competing acoustic signals (including dichotic listening); and auditory performance with degraded acoustic signals”

What is (Central) Auditory Processing Disorder [(C)APD]?

According to ASHA,(Central) Auditory Processing Disorder [(C)APD] refers to difficulties in the perceptual processing of auditory information in the CNS as demonstrated by poor performance in one or more of the above skills”, and the cause of which cannot be attributed to deficits or delays in cognition, language, attention skills or other disorders (e.g. Autism, learning disability, etc).  With that said, APD can at times coexist with other disorders but is NOT the result of the coexisting disorder.

In other words “(C)APD is best viewed as a deficit in the neural processing of auditory stimuli that may coexist with, but is not the result of, dysfunction in other modalities”.

Although skills such as phonological awareness, auditory memory (including attention skills to auditory information presented), auditory comprehension, auditory synthesis, and other similar skills may be reliant on the auditory process, they are considered higher level cognitive-communication skills or language-related functions and are not included in the definition of (C)AP.

How does APD affect my child’s development?

Although (C)APD affects individuals differently, school-age children can demonstration difficulties in a number of areas:
·         learning difficulties
·         speech production deficits
·         language deficits (comprehension and expression)
·         reading delays
·         writing deficits
·         behavioral, emotional and social difficulties

(C)APD Screening:

·         Can be conducted by audiologists, SLPs, psychologists, and others using a variety of measures that evaluate auditory-related skills
·         Screenings usually consist of:  observation of listening behavior,  performance on tests of auditory function, questionnaires, checklists, and other related measures that look at auditory behaviors related to academic achievement, listening skills, and communication.
·         At this time there is no universally used method of screening and screenings should not be used as diagnostic tools.

(C)APD Evaluation: (Due to the inconsistency of language, cognitive and auditory skill development in young children, it is believed that children below the age of 7 cannot be effectively diagnosed with (C)APD.  In fact some professionals believe that diagnosis cannot be consistent or effective prior to the age of 10 years; the age at which the Central Auditory System is considered fully developed.)

·         Can only be conducted by an audiologist familiar and experienced in this area of specialty
·         ASHA’s code of ethics discusses 13 principles to APD testing:

1. the audiologist should have the knowledge, training, and skills necessary to do testing.
2. The test battery process should be motivated by the referring complaint and the relevant
information available to the audiologist.
3. Tests used should have good reliability and validity
4. A central auditory test battery should include measures that examine different central processes.
5. Tests generally should include both nonverbal (e.g., tones, clicks, and complex wave-forms) and
verbal stimuli
6. The audiologist should be sensitive to attributes of the individual.
7. the audiologist needs to determine the appropriate tests for each individual.
8. The audiologist should be sensitive to the influences of mental age on test outcomes. When testing
children below the mental age of 7 years, task difficulty and performance variability render
questionable results on behavioral tests of central auditory function.
9. Test methods should be consistent with the procedures defined in the original research of the test or
as specified in the test manual or literature.
10. The duration of the test session should be appropriate to the person's attention, motivation,
and energy level, and should permit the measurement of a variety of key auditory processes.
11. SLPs, psychologists, educators, and other professionals should collaborate in the
assessment of auditory processing disorders, particularly in cases in which there is evidence of
speech and/or language deficits, learning difficulties, or other disorders. The speech-language
pathology assessment provides measures of speech and language ability and communicative function,
and assists in the differential diagnosis of an auditory processing disorder.
12. In cases in which there is suspicion of speech or language impairment, or intellectual, psychological,
or other deficits, referral to the appropriate professional(s) should be made. In some cases, this
referral  should precede (C)AP testing to ensure accurate interpretation of central auditory
13. Test results should be viewed as one part of a multifaceted evaluation of the individual's
complaints and symptoms. Examples of other data that should be examined include but are not limited to
systematic observation of the individual in daily life activities, self-assessments, and formal and informal
assessments conducted by other professionals.

Types of tests available for (C)APD:

The types of testing measures available for assessing APD are listed below.  This is not an inclusive list, meaning that an APD assessment is NOT required to include testing types, but  is just a guide for clinicians to understand the types of testing available for (C)APD assessment. (list directly quoted from ASHA website)
1.      Auditory discrimination tests: assess the ability to differentiate similar acoustic stimuli that differ in frequency, intensity, and/or temporal parameters (e.g., difference limens for frequency, intensity, and duration; psychophysical tuning curves; phoneme discrimination).
2.      Auditory temporal processing and patterning tests: assess the ability to analyze acoustic events over time (e.g., sequencing and patterns, gap detection, fusion discrimination, integration, forward and backward masking).
3.      Dichotic speech tests: assess the ability to separate (i.e., binaural separation) or integrate (i.e., binaural integration) disparate auditory stimuli presented to each ear simultaneously (e.g., dichotic CVs, digits, words, sentences).
4.      Monaural low-redundancy speech tests: assess recognition of degraded speech stimuli presented to one ear at a time (e.g., filtered, time-altered, intensity-altered [e.g., performance-intensity PI-PB functions]), speech-in-noise or speech-in-competition).
5.      Binaural interaction tests: assess binaural (i.e., diotic) processes dependent on intensity or time differences of acoustic stimuli (e.g., masking level difference, localization, lateralization, fused-image tracking).
6.      Electroacoustic measures: recordings of acoustic signals from within the ear canal that are generated spontaneously or in response to acoustic stimuli (e.g., OAEs, acoustic reflex thresholds, acoustic reflex decay).
7.      Electrophysiologic measures: recordings of electrical potentials that reflect synchronous activity generated by the CNS in response to a wide variety of acoustic events (e.g., ABR, middle latency response, 40 Hz response, steady-state evoked potentials, frequency following response, cortical event-related potentials [P1, N1, P2, P300], mismatch negativity, topographical mapping). The use of electrophysiologic measures may be particularly useful in cases in which behavioral procedures are not feasible (e.g., infants and very young children), when there is suspicion of frank neurologic disorder, when a confirmation of behavioral findings is needed, or when behavioral findings are inconclusive.”

The SLPs role in (C)APD:

ASHA’s Scope of Practice in Speech-Language Pathology statement explains the SLP’s role in (C)APD should focus on “collaborating in the assessment of (central) auditory processing disorders and providing intervention where there is evidence of speech, language, and/or other cognitive-communication disorders”.

Treatment of (C)APD:

ASHA describes three main types of treatments for (C)APD:

1.       Direct Skills Remediation or Auditory Training:  this treatment approach is designed to resolve or reduce (C)APD.  Direct remidiation should be deficit specific, intense and frequent (often requiring daily sessions for several weeks), and adequately challenging (between 30-70% accuracy; 70% accuracy MUST be met before increasing difficulty of taks).  Auditory training tasks should require active participation and provide immediate feedback and reinforcement to maximize learning.  Auditory training activities include (not limited to):
a.       Activities targeting intensity, frequency and duration discrimination
b.      Phoneme discrimination
c.       Phoneme-to-grapheme skills
d.      Temporal gap discrimination
e.       Temporal ordering or sequencing
f.       Pattern recongnition
g.       Localization/lateralization of sound
h.      Recognition of auditory information presented with competing background noise

For a number of specific FREE auditory training activities go to Bonnie Terry Learning

2.      Compensatory strategies training: treatment approach designed to minimize the impact of residual (C)APD unable to be resolved via auditory training and that affects or exacerbates deficits in language, cognitive and academic areas.  Strategies themselves are not effective in remediating the effects of (C)APD but should be practiced often and in various communication environments as one with (C)APD will most likely require the use of these strategies over his/her lifetime to be successful.  There are 2 main types of strategies.
a.       Metalinguistic strategies:  include
                                                              i.      Schema inducation and discourse cohesion devices
                                                            ii.      Context-derived vocabulary building activities (e.g. pre and post-teach academic vocab)
                                                          iii.      Phonological awareness skills (e.g. letter/sound ID, rhyming, decoding, encoding, segmenting/blending of sounds/syllables)
                                                          iv.      Semantic network expansion activities (e.g. synonyms, antonyms, homonyms, categories)
b.      Metacognitive strategies:
                                                              i.      Self-instruction
                                                            ii.      Cognitive problem solving
                                                          iii.      Assertiveness training (also focus on improving self-reliance and self-efficacy)

3.    Environmental modifications: goal is to improve presentation of information at class, work or other communication environments.  Strategies  focus on enhancement of the signal and listening environment.  The following is a list of more common strategies used but this list is far from comprehensive.
a.       Preferential seating (means close to the point on instruction)
b.      Use of visual aids
c.       Reduction of competing signals and reverberation of acoustic sounds
d.      Use of assistive listening systems   (Note:  The strongest indicators for the use of personal FM as a management strategy are deficits on monaural low redundancy speech and dichotic speech tasks which  involve degraded signals, figure-ground, or competing speech that are similar to the effects of noise and reverberation)
e.       Have other speakers present auditory information slowly, pause more often, and emphasize key words

You can find a more complete list of classroom accommodations and modifications below:
Accommodations and Modifications for the Classroom

What should you do if you suspect your child has (C)APD?
Contact an experienced audiologist in your area for a consultation.

If you are an audiologist or an SLP who is well-versed in (C)APD, feel free to comment below.

Happy Talking! 


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