Children with central auditory processing disorder (CAPD), have difficulty understanding what they hear. This is because their ears and brain do not fully coordinate with each other and the brain has difficulty recognizing and interpreting sounds, especially speech. Jack Katz defines Central Auditory Processing as “what we do with what we hear” or as Frank Musiek puts it “How the ear talks to the brain and how the brain understands what the ear is telling”.
According to Muthuselvi et al, (2010), central auditory processing disorder is a difficulty that affects 3.2% of school-aged children in India. This data is similar to Chermak et al, 2007, who also found that the prevalence of CAPD is 2-3% in the pediatric population.
With early intervention, children with Auditory Processing Disorders (APD) can overcome the difficulties faced in school and life, therefore early identification is very crucial. If the identification and management are delayed, a child is at risk for listening and learning problems at home and school.
Understanding Central Auditory Processing Disorders (CAPD): When a sound passes through the ears it is refined by the various auditory structures and is passed on to the brain where it is identified, processed, and given meaning. Central auditory processes involve various mechanisms like localization (locating the sound source), discrimination (understanding what we hear), auditory performance when the signal is degraded (distorted sound source), and auditory performance in noise. A deficiency in any of these areas is called central auditory processing disorder.
Causes of CAPD: There is not a specific cause for central auditory processing disorders. In children, it may occur due to inadequate development of the auditory centers in the brain, which may or may not resolve by itself as the child matures. In other cases, it can be caused due to,
Core characteristics of CAPD: A Child with CAPD will have normal hearing levels but will often have difficulty in;
Speech is exceedingly dynamic and varies from person to person. All humans may not have the same intonation, rhythm, and stress patterns when they speak, which can be due to the geographical area they grew up or their mother tongue, etc., but usually, the brain is highly efficient to comprehend these variations and provide meaning but for children with CAPD, the efficiency of the system is impaired making it difficult for them to pick up on these variations. Due to all these symptoms, often kids with CAPD are misdiagnosed and misunderstood.
Myths surrounding CAPD
Fact - Children with CAPD, often misunderstand speech and are unable to follow instructions, they are often misconceived to be having hearing loss. Because of this misconception people usually speak loudly to them but the result will be the same as when spoken to in normal loudness. Specialized auditory tests are available to identify CAPD, and therefore, parents and other medical professionals should always observe the child and see if it is a hearing difficulty or a listening difficulty.
Fact-A child’s intelligence cannot be associated with CAPD. Usually, children with CAPD, have average to above-average intelligence even though it may not seem like (due to their lack of attention, learning difficulty, inability to follow instructions, slowness to respond to questions, etc). Children with CAPD may score lower than their peers on verbal IQ tests, but this is only because they are unable to process and understand the verbal signals.
Fact-Children with CAPD are frequently misunderstood as being lazy and rude because they are slow to follow and respond to verbal instructions. Often, they mishear questions and give wrong or unrelated answers. Further, they may have difficulty completing assignments, schoolwork, and chores especially when the tasks are assigned orally.
Fact- Children with CAPD and ADHD often show similar symptoms including being inattentive and easily distracted. And often children with CAPD are also diagnosed to be having ADHD but research has revealed that kids with ADHD have difficulty paying attention in various settings and kids with CAPD have difficulty paying attention mainly in the auditory setting. The attention difficulty is specifically more when auditory input is given in a noisy background and when multiple instructions are given verbally.
Fact-Researchers have estimated the prevalence rate of CAPD is approximately 2%–5% in the school-age population. The prevalence of APD in the older adult population varies - ranging from 50% in clinical studies to around 23% in a longitudinal population study.
Who can work with children having CAPD? A multidisciplinary team approach plays a significant role in the effective management of CAPD. The core responsibilities are carried by the speech-language pathologists and audiologists. The speech-language pathologist has to identify the auditory processing difficulty after confirming that the hearing is normal. This can be achieved by observing the child and going through the various speech and language tests.
Then, the audiologist is roped in as they are the only ones who can provide a diagnosis. The speech-language pathologist should continue with speech therapy and vary the therapy plan that will accommodate auditory training and work on improving communication. Psychologists and psychiatrists will effectively manage the attention issues faced by these children. The educators and special educators should also be included in the team and should provide strategies that the children can use to make school easier. If the child has a seizure disorder a Neurologist should be consulted to effectively manage the seizures.
Thus, the team should involve an audiologist, speech-language pathologist, educators, special educators, and a neurologist (in the presence of seizures/ seizure disorder). When there is an associated hyperactivity, a child Psychiatrist’s help should be sought.
What are the other co-morbid conditions? CAPD can occur independently or can coexist in children. Commonly occurring co-morbid conditions of CAPD are listed below;
All of the above listed can have auditory processing difficulties. So, audiologists and speech-language pathologists have a huge responsibility in efficiently identifying CAPD.
Identifying CAPD: Many tests are available that can be used to identify CAPD. And these tests can be categorized into electrophysical and behavioral tests.
Electrophysical tests assess the neural function of the central auditory pathway and provide information about the integrity of the central auditory nervous system from the auditory- vestibular nerve to the auditory cortex. These tests are auditory brainstem response (ABR), middle latency response (MLR), late cortical response, P-300, and mismatch negativity.
The behavioral tests assess the different functional capabilities of the auditory system. The functions include the ability to discriminate similar acoustic signals (auditory discrimination tests), the ability to process the variation of acoustic signal over time (auditory temporal processing and patterning tests), ability to separate and integrate auditory stimuli picked up by both the ears (dichotic speech tests), the ability to process degraded stimuli which are assessed using monoaural low redundancy speech tests, and the ability to combine corresponding inputs between the two ears (binaural interaction tests). However, one should have a good age-matched normative data on each test for interpretation of the test results of a particular child suspected for CAPD.
In private speech therapy practice, the identification of CAPD depends on the facilities available at the setup. The first essential step in identifying CAPD is giving importance to case history, academic profile, and behavioral observation. These give many clues that can help therapists to identify the difficulty faced by the child. The hearing thresholds have to be assessed to confirm that the issue is not related to hearing acuity. Although an audiologist is the only person who can diagnose CAPD, the other professionals can also gather information so that there is no delay in the identification of the disorder.
Screening of CAPD can be done using several questionnaires and checklists which examine the auditory behaviors related to academic achievements, listening skills, and communication. These screening tools allow the examiner to do a systematic observation of the listening behavior.
Some of the screening checklists include
All professionals need to be vigilant and efficient in identifying the auditory processing disorder, so that there is no delay in treatment.
Treating CAPD: Treatment for CAPD is based on the needs identified during the assessment process. The treatment should address auditory discrimination, phoneme discrimination, temporal aspects of hearing, auditory pattern recognition, sound localization and lateralization, recognition of auditory information in the presence of noise, and recognition of different auditory signals presented to both ears simultaneously. If the intervention of CAPD is not done effectively it will affect the child’s academic proficiency, psychosocial skills, ability to listen and communicate.
Here are a few strategies and games that can be used to improve some of the listening skills in children with CAPD.
Strategies for parents and teachers: Parents and Teachers have an important role to play in the development of a child, as they are the people who spend the most time with the kids. Different strategies can be adapted in daily life at home as well as in school, to make communication, attention, and participation easier for children. Following are a few helpful strategies.
Source: This blog is a summary of the Facebook Live session with Prof. N. Shivashankar the former Professor and Head, Dept. Speech Pathology and Audiology & former Associate Dean at NIMHANS, Bengaluru. He has several national and international publications, book chapters and awards to his credit.
Prof. N. Shivashankar is currently a Sr. Consultant at Apollo Hospital, Jayanagar, Bangalore.
Compiled By, Ida Varghese and Chitra Thadathil (Speech Language Pathologists)
References and further reading