Central Auditory Processing Disorder (CAPD) 101: Symptoms, Causes & Treatment

What is Central Auditory Processing Disorder (CAPD)?

Central Auditory Processing Disorder (abbreviated as CAPD), sometimes referred to as Auditory Processing Disorder (APD), is when a person faces difficulty processing sounds they hear. Sound waves that reach a person’s ears are converted into electrical signals that travel to the brain. The brain analyzes this signal and interprets it as a sound we can recognise. Impaired neural function prevents the brain from correctly processing audio information that a person hears.

This means a person with CAPD can still hear sounds and does not face any hearing difficulties; the ears and their internal structures are unaffected. They will, however, have trouble understanding what is being said to them, or correctly identify what sounds they hear in their surrounding environment. It is because the brain perceives these sounds incorrectly, and the person is unable to respond properly or in a timely manner.

Another consequence of CAPD is difficulty in filtering out background noise. Sounds emitted by a ceiling fan or cars passing by from a distance can greatly interfere with conversations, further distorting what they hear. In some cases, these noises can even irritate them or cause considerable discomfort.

As a consequence, even simple statements such as, “Hello, how are you?” may be misinterpreted entirely by someone with CAPD.

CAPD generally affects between 2-5% of children or approximately half of all children with learning disorders. However, it can also be diagnosed in adults, especially in senior citizens. It is important to note that CAPD is not an intellectual disability. There are children with autism spectrum disorder (ASD) or attention deficit hyperactivity disorder (ADHD) who also have CAPD, but these are not the main cause of CAPD. CAPD affects a person’s ability to communicate and comprehend what others are saying, compounded by a variety of factors.

Symptoms of Central Auditory Processing Disorder (CAPD)

There are various symptoms of CAPD, ranging from mild to severe conditions. These include, but are not limited to, the following:

• Difficulty in paying attention; easily distracted/unattentive
• Sensitive to background noise and/or loud sounds
• Cannot recall verbal information presented to them
• Learning difficulties (reading, writing, spelling, etc.)
• Unable to correctly determine where a sound is coming from
• Unable to differentiate between words that sound like each other (e.g. ‘ate’ and ‘eight’)
• Difficulty following long conversations, or instructions with multiple steps
• Requires more time to process verbal information
• Unable to understand verbal cues, i.e. sarcasm, jokes, etc.
• Unable to understand fast or unclear speech, or when talking in a loud environment|
• Frequent requests to repeat verbal information

CAPD cannot simply be diagnosed solely based on these symptoms. In fact, it is misunderstood due to an overlap with other learning and/or auditory disabilities. It is why CAPD is commonly confused with ADHD or even dyslexia, but they are not the same.

In children with ADHD, they may show inattentiveness and hyperactivity in any environment, while children with CAPD may not have any difficulty when learning and communicating in a quiet environment, and only face difficulty when in a noisy environment.

In the case of dyslexia, 25% of all children tested for learning disabilities also had coexisting APD and dyslexia. However, both have distinct traits: dyslexia is a reading disorder, where they have difficulty understanding and processing written words into spoken words. CAPD is characterized by a difficulty in understanding and processing spoken words in a meaningful way, especially when it comes to discerning certain phrases or words.

Causes of Central Auditory Processing Disorder (CAPD)

The causes of CAPD are not fully understood. Medical professionals believe the causes of CAPD are influenced by a number of factors, including:

• Chronic illnesses (i.e. multiple sclerosis)
• Frequent ear infections (i.e. otitis media)
• Family history of CAPD (genetics)
• Developmental issues with the auditory pathways
• Cranial/brain injury
• Poor prenatal/postnatal care (i.e. low birth weight, premature birth)
• Exposure to neurotoxins (i.e. heavy metals)
• Age-related changes
• Blast exposure (among combat veterans)

A child’s auditory pathways are not fully mature until they reach 10 to 12 years of age. It is therefore important to identify CAPD early, as early intervention can lead to significant improvement as the child grows older.

Diagnosis of Central Auditory Processing Disorder (CAPD)

The diagnosis of CAPD is done by a team of audiologists and/or speech-language pathologists. Audiologists are medical professionals responsible for identifying, assessing and treating hearing-related problems. Speech-language pathologists, on the other hand, help prevent,  assess, diagnose, and treat speech, language and communication problems. Other medical professionals, including psychologists or speech therapists, may also work together as part of a multidisciplinary team. This ensures accurate results from the diagnosis, which in turn allows them to form an appropriate treatment plan.

Initial diagnosis must take into account the overlap of symptoms in other issues such as ADHD and dyslexia. Though there is no defined “gold standard” to assess for CAPD, a series of standardized tests will be conducted to make an initial diagnosis. These are undertaken to determine if there are disorders with similar symptoms to CAPD or determine if additional CAPD testing is needed.

Testing will also be based on other criteria, such as a person’s age, cultural background, academic achievements, referral source, risk factors and other health concerns, if present. The attending audiologist(s) will know which test(s) to apply, in view of the information available to them.

It must be stated that CAPD testing is only done from age 7 and above. According to the American Academy of Audiology, the brain functions involved in testing are still developing in young children, and their responses to these tests may not be completely accurate.

Some tests that may be done include the following:

• Evaluate oral and written communication skills
• Listening to audio input and repeating what was presented
• Gauge brain activity while listening to sounds
• Test hearing skills as background noise is steadily increased
• Dichotic listening, or identifying two distinct sounds from different sides
• Temporal processing to identify differences in sounds

Central Auditory Processing Disorder (CAPD) Treatment

While CAPD has no cure and cannot be medicated, there are a number of treatment options that can help a person with CAPD to manage their condition and allow them to lead normal lives. Treatment will be based on the diagnosis made by the medical team. They can be oriented around therapy, compensating strategies, and even changes to the surrounding environment.

Auditory Training

Auditory training helps a person with CAPD in being able to identify and process sounds better. These can be conducted on a one-to-one basis with a therapist. Auditory training may involve the following exercises:

• Distinguishing one sound being played from another
• Differentiate similarities and differences between sounds
• Distinguishing specific verbal sounds from one another
• recognise speech or sound patterns within a background of noise
• Determine where a sound is coming from

Speech-language pathology, or speech therapy, is one such auditory training method. It aims to directly address auditory processes that need to be treated. Constant supervision and practice are key to lead to successful remediation.

There are also computer-based auditory training methods that make use of multisensory approaches and engaging formats that make a more intuitive therapy experience. These approaches can make it easier to develop the needed auditory processing skills to manageable levels.

Compensatory Approaches

Compensatory methods help with improving memory, attention, problem-solving and their other senses in coping with CAPD. Some examples include:

• Using visual aids to help organise information
• Predicting potential messages in a conversation
• Learning assertiveness to make up for listening deficiencies
• Phonological awareness (recognising and manipulating spoken sentences and words)
• Practice active listening
• Mind mapping

Environmental Changes

Environmental changes refer to modifying the learning or communication environment that one occupies. These also include strategies in communicating with those with CAPD.

• Using hearing assistive technology (e.g. hearing aids)
• Covering reflective surfaces with soft materials (e.g. rugs, carpets)
• Remove or reduce sources of noise generation, or other forms of distraction
• Make use of seating arrangements beneficial to those with CAPD 
• Encourage repetition of something that might not be initially understood
• Clear, concise speech, in tandem with visual cues

Environmental changes are the easiest treatment strategy to implement, but may not entirely address a person’s condition or suit their preferences in coping with CAPD. This is best used in tandem with other treatment methods to effectively manage CAPD.

Caring for a Loved One with CAPD

CAPD is manageable with proper care and constant training with proper support and therapy. It is very important for regular follow up treatments and/or consultations to be held. This will ensure that the treatment is going well, while helping to gauge the overall progress made throughout.

Outside of therapy sessions, there are ways you can help a loved one cope with CAPD:

• Have conversations in the absence of background noise
• Apply soft materials (i.e. rugs) to hard surfaces, where possible
• Make sure the person is ready to listen to you before starting a conversation
• Speak clearly, slowly, and pausing between sentences
• Encourage them to repeat what you have said, or ask questions if needed
• Break down instructions with multiple steps into step-by-step actions
• Let them use hearing aids that reduce background noise

If you need further information on CAPD, whether to provide care or support to someone or to understand the importance of early intervention, you can always seek professional advice.

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