This document provides an introduction to central auditory processing disorder (CAPD), including definitions, prevalence, symptoms, screening, classification of deficits, and processes involved. CAPD is estimated to affect 2-7% of school-aged children and is characterized by difficulties processing auditory information in the central nervous system despite normal peripheral hearing. Symptoms include problems understanding speech in noise, sequencing sounds, and auditory attention. Screening tools evaluate skills like auditory closure, memory, and figure-ground processing to identify children for full evaluation.

1. Topic – Introduction to Central Auditory Processing Disorder (CAPD): Signs & Symptoms
Presented By – Piyush Malviya
Session – 2021

2. Contents
• Introduction
• Definitions
• Prevalence
• Central Auditory Processing Disorders
• Symptoms of CAPD
• Red Flag Signs for Children with CAPD
• Deficits in CAPD
• Screening of CAPD

3. • Classification of CAPD
• Processes involved in CAPD
• Considerations
• Challenges & Controversies
• ASHA Conference
• References

4. Introduction
• In its very broadest sense, APD refers to how the central nervous system (CNS) uses
auditory information.
• However, the CNS is vast and also is responsible for functions such as memory, attention,
and language, among others.
• Individuals with CAPD usually have normal structure and function of the peripheral
hearing systems.
• However, due to dysfunction in the central auditory nervous system, they cannot process
the information they hear in the same way as others do, which leads to difficulties in
recognizing and interpreting sounds, especially the sounds composing speech.
• Although epidemiological studies of the prevalence of CAPD are difficult to conduct, it has
been estimated that as many as 5% of school-aged children have some version of the
disorder.

5. Definitions
• Auditory processing disorder (APD), also known as central auditory processing disorder
(CAPD) is an umbrella term for central auditory deficits that affect the way the brain
processes auditory information. (Hearing in Children, Northern & Downs, 6th Edition)
• An interference with the central auditory nervous system(CANS) from the cochlear nuclei
to the auditory cortex in the temporal lobe including the interhemispheric pathways may
result in central auditory dysfunction. (Essentials of Audiology, Stanley A. Gelfand, 4th
Edition)
• ASHA(1992) defined (C)APD as having difficulty in retrieving, transforming, analyzing,
organizing and storing information from audible acoustic signal.
• (C)APD is defined as “a deficit in the perceptual processing of auditory stimuli and the
neurobiological activity underlying that processing”
- ASHA,2005
• Bellis (2002a, 2002b) aptly describes CAPD as a hearing problem in which "the brain
can't hear."

6. Prevalence
• The number of children with CAPD is between 2-7%.
• Boys are twice as likely as girls.
• 5% of school age children are reported to have APD.
• APD is often un/misdiagnosed because of other coexisting disorders(ADHD, dyslexic, LD
and PDD).
• 25% children with learning disability have APD.
• Up to 50% of children with dyslexia have APD.
- Joshua Nelson: Overview of Special Education(1988);

7. Central Auditory Processing Disorder
• CAPD is more formally defined as a deficiency in the perceptual processing of auditory
information in the central auditory nervous system (CANS) as demonstrated by poor
performance in one or more of the following skills: 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 (ASHA, 2005).
• A similar definition of CAPD was described by the British Society of Audiology (2011) who
added that CAPD should be assessed through standardized tests of auditory perception.
CAPD may coexist with, but is not the result of, dysfunction in other modalities.
• CAPD can be genetic in origin or can be caused by disease processes, neurological
conditions, traumatic brain injury, developmental abnormalities including delayed
maturation of the central auditory nervous system, and metabolic disorders (Bamiou,
Musiek, & Luxon, 2001).

9. • There is also growing evidence that in some children auditory deprivation due to early and
longstanding otitis media results in impaired development of central auditory pathways
and structures with consequential auditory processing deficits (Moore, 2007; Whitton &
Policy, 2012).
• CAPD is more likely to occur with other conditions than in isolation. Common
comorbidities include dyslexia, attention deficit hyperactivity disorder (ADHD), autism
spectrum disorder (ASD), and specific language impairment and reading disorder (Sharma
et al., 2009).
• Sometimes comorbidities may be consequences of the APD.
• For example, APD may affect language development and reading through its effects on
phonological skills.
• Auditory processing deficits are also a key underlying factor in dyslexia (Burns, 2013).
• Inattention due to poor ability to hear may sometimes at first be misinterpreted as an
attention disorder, but APD can be distinguished by results of auditory tests.
• Nonetheless, there is considerable comorbidity between APD and ADHD.

12. Symptoms of CAPD
• The subjective symptoms that lead to an evaluation for CAPD include an intermittent
inability to process verbal information, leading the person to guess to fill in the processing
gaps.
• There may also be disproportionate problems with decoding speech in noisy
environments.
• CAPD can manifest in children as problems for them to determine the direction of sounds,
difficulty perceiving differences between speech sounds, and the sequencing of these
sounds into meaningful words, confusing similar sounds such as "hat" with "bat," "there"
with "where," etc.
• Fewer words may be perceived than were actually spoken, as there can be problems
detecting the gaps between words, creating the perception that someone is speaking
unfamiliar or nonsense words.
• Those suffering from CAPD may have problems relating what has been said with its
meaning, despite obvious recognition that a word has been said.
• People with auditory processing disorder sometimes subconsciously develop visual coping
strategies, such as lip reading, reading body language, and reliance on other visual cues,
to compensate for their auditory deficit.

13. • Descriptions of speech perception by adults with APD are informative.
• They report that speech seems fast, fragmented, and confusing, and that any other sound
can seem to drown it out.
• They Often hear the start of a sentence or paragraph but understand less and less it
progresses.
• They mishear some phonemes or speech sounds, they sometimes jumble the order of
sounds, and they may miss pitch or intonation cues that affect the meaning of spoken
language.
• They also report difficulty in localizing sounds.
• Children with CAPD are known to exhibit one or more of a wide range of behaviors as they
experience language and learning problems (Keith, 2000a):
 inconsistent responses to auditory stimuli;
 inability to follow auditory instructions;
 difficulty with auditory localization;
 inability to differentiate soft and loud sounds;
 unexplainable fear of loud noises, or being overwhelmed by the auditory
environment;
 difficulties in learning, discriminating, and remembering phonemes and
manipulating them in tasks such as reading, spelling, and phonics;

14.  poor perception of pitch, intonation, and other suprasegmental features of speech
that affect meaning;
 difficulty understanding speech in noisy backgrounds or against any competing
sounds;
 impaired ability to recall and repeat simple musical patterns of high- and low-pitch
notes or temporal (rhythm) patterns;
 difficulty with auditory memory, cither span or sequence;
 poor listening skills with decreased attention, increased distractibility, and
restlessness;
 frequent requests to repeat information;
 Low academic performances significant reading problems,poor spelling;
 behavioral problems; and
 withdrawal tendencies, shyness with poor self-concept resulting from multiple
failures

15. Red Flag Signs for Children with CAPD
The presence of one or more the following key symptoms in the presence of normal
peripheral hearing is a useful indicator in identifying children who should be assessed
with CAPD -
• Difficulty following spoken directions unless they are brief and simple;
• Slowness in processing spoken information;
• Difficulty attending to and remembering spoken information;
• Poor listening skills ;
• Difficulty understanding in the presence of other sound;
• Difficulty with language, reading, spelling, writing, vocabulary, or comprehension.

16. Deficits in CAPD
• CAPD was defined as involving deficits in:
 Sound localization and lateralization
 Auditory discrimination
 Auditory pattern recognition
 Temporal aspect of audition (temporal resolution, temporal masking,
temporal integration, temporal ordering)
 Auditory performance with competing or degraded acoustic signal
- JACK KATZ (handbook of audiology- 7th edition)

17. • CAPD particularly affects temporal processing of auditory information which in turn
affects the recognition and discrimination of phonemes.
• Impaired phonological awareness in turn may affect auditory memory (if stored templates
of sounds are deficient), language, spelling, and reading.
• The perception of rapid format transitions is impaired in CAPD and dyslexia (Hornick et
al., 2012), and research also shows impaired perception of slow temporal aspects of
spccch (Corriveau, Goswami, & Thomson, 2010).
• Approximately half of children with CAPD have amblyaudia, a unilateral weakness or
inhibition of one ear affecting binaural integration.
• Amblyaudia (amblyos- blunt; audia-hearing) is a term coined by Dr. Deborah Moncrieff to
characterize a specific pattern of performance from dichotic listening tests.
• Amblyaudia presents as an abnormally large interaural asymmetry on dichotic testing.
• Amblyaudia is a deficit in binaural integration of environmental information entering the
auditory system.

18. • It is a disorder related to brain organization and function rather than what is typically
considered a “hearing loss” (damage to the cochlea).
• It may be genetic or developmentally acquired or both.
• Amblyaudia may adversely affect any aspect of hearing requiring binaural function for
optimal audition (Moncrieff, 2011).
• Keith (1988) hypothesized that some basic auditory-perceptual skills (e.g., appreciation of
frequency, intensity, and duration of sounds) exist in every child and serve as building
blocks of audition, leading to language development through imitation.
• As language skills are acquired, children also learn to apply auditory-perceptual skills,
such as memory, discrimination, closure, and blending to language.
• In addition, as the child's neuroanatomical pathways mature, the ability to cope with
higher level auditory tasks such as dichotic listening and binaural release from masking
begins to improve.

19. Screening of CAPD
• A number of screening tests to identify children who might have CAPD have been
developed.
• Although these screening tests are in no way intended to be diagnostic, they can be useful
in obtaining information on children too young for formal CAPD assessment.
• Because CAPD is not a singular entity but rather an umbrella term for a range of central
auditory deficits, effective screening is not possible unless the screening tool incorporates
a sensitive test for every possible deficit.
• However, the list of key symptoms presented earlier can be very effective in detecting
children who should be evaluated.
• Groups that warrant almost automatic referral for central auditory evaluation include
children with dyslexia and children with reading disorders.
• Although a number of questionnaires have been used to screen for CAPD, they generally
have poor specificity, tend to under- or overrefer, and have not been completely validated.

20. • A number of CAPD screening tests are currently in use including –
1. The Children's Auditory Performance Scale (CHAPS), a 25-item scale that utilizes a
scaling continuum related to the child's auditory behaviors (Smoski, Brunt, &
Tannahill, 1992);
2. The Children's Home Inventory for Listening Difficulties (CHILD), for use with
children between the ages of 3 and 12 which is completed by a parent (Anderson &
Smaldino, 2000);
3. The Listening Inventory (TLI) developed by Geffner and Ross-Swain (2006);
4. The Screening Instrument for Targeting Educational Risk (SIFTER) from Anderson
and Matkin (1989); and
5. The Listening Inventory for Education (LIFE) (Anderson & Smaldino, 1998).
6. Screening Test for Auditory Processing (STAP) {Indian Test} [Yathiraj & Maggu] -
The test was designed to address auditory separation/closure, binaural integration,
temporal resolution, and auditory memory in school-age children; The study also
aimed to examine the number of children who are at risk for different auditory
processes; Age Range: 8 Years to 13 Years
7. Screening checklist for auditory processing (SCAP) {Indian Test} [Yathiraj and
Maggu, 2013]

21. • Despite their limitations, these instruments can provide useful background information
for the evaluation.
• Most tests of CAPD are based on some form of challenging auditory signal for the auditory
nervous system to identify as in speech-in-noise or distorted speech tests.
• These tests, known as sensitized speech tests, use various means of distorting speech
to reduce the intelligibility of the message.
• Distortion can be accomplished in many ways including high- or low-pass filtering that
reduces the range of frequencies (filtered speech testing).
• Another approach is to reduce the intensity level of speech above a simultaneously
presented background noise (auditory figure ground testing).
• Speech can be distorted in the time domain by interrupting the speech at different rates,
and by increasing the rate of presentation (time compressed speech).
• Persons with normal hearing and normal auditory pathways can understand distorted
speech messages; however, when a central auditory processing disorder is present,
speech intelligibility under difficult circumstances is poor.
• The construct of sensitized speech testing is extremely powerful and forms the basis of all
behavioral speech tests of central auditory function (Keith, 1999a)

22. Classification of CAPD
MODELS
BELLIS/
FERRE
MODEL
Consist of three primary processes- auditory
decoding deficit, prosodic deficit,
integration deficit. Two secondary processes-
associative deficits, o/p organization deficit.
THE BUFFALO
MODEL
Given by Katz et.al.(1998) consist of:
decoding deficit, tolerance-fading memory
deficit, integration (types 1st & 2nd)deficit,
organization deficit.
S-PL
MODEL Considers auditory processing to be a
component of spoken-language-processing
(S-LP)

23. Processes Involved in CAPD
• Several processes are involved in auditory perception, they are:
 Binaural integration – The ability of a listener to process information being presented to
both ears simultaneously, with the information presented to each ear being different.
 Binaural Separation – The ability of a listener to process auditory message coming to
one ear while ignoring the information provided to the other ear.
 Binaural Interaction – The way in which two ears works together, include localization &
lateralization, binaural fusion.
 Auditory Closure – Ability to utilize extrinsic and intrinsic redundancy to fill in missing
and distorted portion of auditory signal and recognize the whole message.

24.  Temporal Processing –
1. Temporal Sequencing/Ordering – The ability to precisely perceive the sounds in order of
its occurrence.
2. Temporal Resolution – The ability to perceive changes in auditory stimulus with time.
3. Temporal Masking - The ability of one sound (masker) to mask another sound (probe) that
precedes and/or follows it.
4. Temporal Integration or Temporal Summation - Is the ability of the auditory system to
add up information over time up to a critical duration.
 Sound localization and lateralization - The ability to locate the source of a sound through
hearing only; This ability requires simultaneous binaural stimulation
 Auditory attention – The ability to persist in listening over a reasonable period.

25.  Figure Ground - The ability to identify a primary signal or message in the presence of
competing sounds; Auditory figure ground can be a monaural or a binaural task,
 Auditory memory and sequencing - The ability to store and to recall auditory stimuli,
including length or number of auditory stimuli, and sequential memory or the ability to
recall the exact order of auditory stimuli presented.
 Blending - The ability to form words out of separately articulated phonemes.
 Cognition - The ability to establish a correspondence between a linguistic sound and its
meaning.

26. Considerations
• Before any attempt is made to administer tests for CAPD, the audiologist must be certain
that no conductive or sensorineural hearing loss is present in either ear of the child.
• Generally, patients with CAPD shows normal hearing for routine audiometric tests,
although that is not to say that CAPD does not coexist in children who do have
substantiated hearing disorders.
• It is critical that a complete assessment of the peripheral auditory system, including
consideration of auditory neuropathy spectrum disorder (ANSD), occur prior to
administering a central auditory test battery.
• At minimum, this would include evaluation of hearing thresholds, immittance measures
(tympanometry and acoustic reflexes), and otoacoustic emissions (OAEs).
• When contradictory findings exist (e.g., present OAEs combined with absent acoustic
reflexes or abnormal hearing sensitivity; abnormal acoustic reflexes with normal
tympanometry and OAEs), additional follow up should occur to rule out ANSD prior to
proceeding with central auditory testing (AAA, 2010; ASHA, 2005).
• It is possible to carry out some CAPD testing in the presence of mild, particularly
conductive, peripheral hearing loss, at increased presentation levels, as long as it is
understood that the results may be compromised and conclusions limited by confounding
variables.

29. References
• Hearing in Children (6th Edition by Jerry L. Northern & Marion P.
Downs)
• Essentials Of Audiology (4th Edition By Stanley A. Gelfand)
• Auditory Diagnosis - Principles & Applications (Shlomo Silman &
Carol A. Silverman)
• Handbook of Clinical Audiology (7th Edition By Jack Katz)
• https://www.asha.org/public/hearing/understanding-auditory-
processing-disorders-in-children/
• https://childmind.org/article/signs-a-child-might-have-auditory-
processing-disorder/
• https://www.youtube.com/watch?v=t5Gx-7s0tVg&t=972s