Not all hearing problems are rooted in the ear. Central auditory processing disorder (APD) is a condition where a person’s brain has a problem processing sounds, affecting 3 percent of the world’s population. This guide will cover all the basic facts about this rare and poorly understood condition.
Understanding Auditory Processing Disorders
This condition isn’t a hearing disorder. People with auditory processing disorder have normal hearing, but their auditory discrimination is poor. The brain has trouble filtering what the ears hear, and it cannot distinguish between similar sounds.
Symptoms
If you’re worried that you or someone you love has an auditory processing disorder, here are a few common signs:
Problems following spoken directions | People with auditory processing disorder can hear words but have difficulty making sense of them, so they might struggle with instructions presented verbally. This symptom often leads to academic difficulties. Auditory processing disorder is often mistaken for ADHD or a learning disability. |
Trouble understanding people who talk fast or speak with an accent | It’s challenging for folks with auditory processing difficulties to distinguish between the subtle differences in some words, especially if the speaker is talking rapidly. This is especially problematic in the presence of background noise. |
No ability to identify the direction of the sound source | Also no ability to detect subtle changes in voice tone. |
Difficulty understanding speech in noisy environments | Also listening to more than one person talk at once. |
In some cases, auditory processing disorder may be accompanied by other disorders, such as:
- Memory problems
- Cognitive function deficits
- Language disorder
- Learning disabilities
Causes
Medical experts still don’t fully understand what causes auditory processing disorder, but research suggests the condition may be linked to:
- Serious infections like meningitis
- Low birth weight
- Multiple sclerosis and other neurological disorders
- Genetics
- Head injuries
Auditory Processing Disorder in Children
A child may develop auditory processing disorder due to premature birth or congenital condition.
Children with impaired auditory processing skills may act out and perform poorly in school, so the condition is frequently misdiagnosed as attention deficit hyperactivity disorder, dyslexia, language disorders, and an autism spectrum disorder.
Testing For APD
There is no single auditory processing disorder test.
A series of medical professionals, including a physician and speech-language pathologist, will administer a battery of tests to rule out alternative explanations and determine where the problem lies. The tests may include:
- Psychoacoustic tests
- Hearing tests
- Auditory brainstem response
- Advance listening tests
- Behavioral health screening
Testing is important to determine if this is APD or some other learning disability.
Diagnosing APD
There are five criteria to diagnose APD.
Pure Tone Audiometry | The hearing threshold should be normal or minimal with a hearing loss of less than 15 dB. An abnormal audiogram can be present with APD. This is extremely rare and would make the diagnosis more difficult. |
Abnormal Audio Processing | The presence of abnormal auditory processing results is the second criterion. A person must perform less than two standard deviations below the mean. These must be assessed in both ears. Different auditory processing tests are applied in one or both ears including non-speech sounds. |
Symptoms and Risk Factors | The presence of listening difficulties and other symptoms and the presence of risk factors associated with APD are also diagnostic criteria. |
Non-Verbal Intelligence Coefficient | This is an IQ test where a person must have an IQ above 80 to be diagnosed with APD. This rules out any cognitive deficits. This is harder to do because there are testing limitations. |
Ability To Follow Instructions | This criterion determines if a person can follow the instruction in ideal circumstances outside of testing. Does this person understand and reliably follow instructions? |
What Is The Treatment For APD?
The treatment for APD is complicated and requires a multipronged approach by a multidisciplinary team that may include doctors, psychologists, and speech-language pathologists.
Core Treatment Focus
This treatment incorporates various strategies to retrain the brain to process sound and equip a person with skills to cope. This includes interventions and allowances. Treatment focuses on three areas.
- Interventions in the learning environment and the way communication takes place.
- Compensatory strategies that employ higher-order skills and critical thinking
- Correcting the auditory deficit itself
Early Intervention
It is defined as the imperfect ability to listen or understand speech.
Early diagnosis is the key to effectively treating this condition.
In younger children, the brain is far more plastic, so it’s easier to reorganize the way the brain processes sound.
Helpful Interventions
To overcome APD, you need to cultivate auditory processing skills with a series of interventions, including:
- Auditory training using software like Fast ForWord and Earobics. It’s important to note that research on these programs has been inconclusive.
- Training with a speech therapist: People with APD have trouble distinguishing between specific sounds and words. A therapist can train them to differentiate between commonly confused sounds like “b” and “p.” Auditory training also involves exposure to auditory inputs to train the auditory pathways to differentiate sound.
- Auditory games: School-aged children with APD can play games like musical chairs with other kids to learn how to identify a sound and where it is coming from.
- Optimizing the environment to eliminate noise: You can remove all sources of background noise by shutting windows and covering hard floors with carpet.
- Assistive technologies: Frequency modulation systems and closed-captioning can help you understand words better.
Controversies in APD
APD is sadly not well understood. There are still disputes in the medical community about causes, classification and other controversies.
For example, some researchers don’t consider APD a processing disorder because the brain is functioning well except for the selective deficit of hearing.
Some degree of processing also occurs within the inner ear, so a disorder in the cochlea may be responsible or implied.
The quality of testing is another gray area. Many of the tests for APD were primarily designed for adults with brain tumors. It’s challenging to use them in children. There is a lack of consensus among Audiologists about the diagnostic criteria because other central hearing deficits could contribute to the APD.
They don’t believe specialized clinics should diagnose and treat the condition. More researchers now want neurologists, hearing professionals, and specialists to work collaboratively on this condition.
There’s a consensus that the standards established 40 years ago for classifying, diagnosing, and treating APD need to be updated.
Conclusion
For people with APD, the diagnosis is very complex. As there is no consensus about auditory processing disorder, while doctors and audiologists have different approaches. The treatment also varies. However, there are various treatment options you can pursue. Work with your medical team to find what works best for you.
Citations
1. Palmer S. (2013) Central Auditory Processing Disorder. In: Volkmar F.R. (eds) Encyclopedia of Autism Spectrum Disorders. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-1698-3_962
2. Bamiou D, Musiek FE, Luxon LMAetiology and clinical presentations of auditory processing disorders—a reviewArchives of Disease in Childhood 2001;85:361-365.
3. Moore DR. Editorial: Auditory Processing Disorder. Ear Hear. 2018;39(4):617-620. doi:10.1097/AUD.0000000000000582