Auditory Processing Disorder (APD)

What auditory processing disorder is

Hearing involves two steps. The ears detect sound and send signals along the hearing nerve. The brain then decodes those signals: separating speech from noise, recognizing small differences between sounds such as "ba" and "da", tracking the order and timing of sounds, and combining input from both ears. APD is a weakness in this second step.

A standard hearing test (audiogram) checks only whether the ears can detect quiet tones. In APD this is usually normal, which can make the difficulties confusing for families and teachers.

Signs of auditory processing disorder

In children

• difficulty understanding speech in noisy places such as classrooms and playgrounds
• frequently asking for repetition or saying "huh?" or "what?"
• trouble following spoken instructions, especially several steps at once
• mishearing similar-sounding words
• slow responses to spoken questions
• being easily distracted by background noise
• difficulty with reading, spelling and phonics
• trouble remembering spoken information
• appearing not to listen or to daydream
• difficulty enjoying music or recognizing tones of voice

In adults

• struggling with conversations in restaurants, meetings or on the phone
• difficulty following fast speech or accents
• trouble locating where a sound is coming from
• mental fatigue after listening for long periods

Adult APD may be lifelong or develop after a head injury, stroke, tumor or with aging.

Causes and risk factors

The cause is often unknown. Associated factors include:

• repeated middle ear infections or glue ear in early childhood, which may disrupt auditory development
• premature birth or low birth weight
• family history
• head injury, stroke or neurological conditions
• aging of the auditory system

Conditions that overlap

APD symptoms overlap with several conditions, and many children have more than one:

Because of this overlap, assessment is best done by a team: audiologist, speech-language pathologist, psychologist and teachers.

Diagnosis

1. Standard hearing test to rule out hearing loss, plus tests of middle ear function.
2. APD test battery by an audiologist. Tests may include: - speech-in-noise tests - dichotic listening (different words played to each ear at the same time) - pattern and timing tests (identifying sequences of tones or gaps in sound) - filtered or compressed speech tests
3. Speech, language and cognitive assessments to identify overlapping difficulties.

Reliable testing usually requires a child to be at least 7 years old, because auditory skills are still developing and the tests demand attention and language.

Treatment and support

There is no medicine for APD. Management combines three approaches:

Changing the environment

• seat the child near the teacher and away from noise sources such as doors, windows and heaters
• reduce classroom noise with carpets, soft furnishings and closed doors
• use remote microphone systems (FM or digital systems): the teacher wears a microphone that sends their voice directly to the child's earpiece or a speaker
• provide written instructions and visual supports

Compensatory strategies

• get the person's attention before speaking
• speak clearly and slightly slower, not louder
• rephrase rather than repeat the same words
• break instructions into short steps
• check understanding
• teach self-advocacy: asking for repetition, choosing a quieter seat

Auditory training

Computer-based or therapist-led exercises that practice sound discrimination, listening in noise and auditory memory. Evidence is mixed but some people benefit, especially when training is targeted.

School support

In the US, children may qualify for a 504 plan or an Individualized Education Program (IEP) with accommodations.

Outlook

Many children's auditory skills improve as they mature, and good strategies and support reduce the impact on learning. Some people continue to find noisy environments harder throughout life but adapt well.

Frequently asked questions

What is auditory processing disorder?

Auditory processing disorder is a difficulty in how the brain interprets sound, even though hearing in the ears is normal. People with APD often struggle to understand speech in background noise, follow spoken instructions and tell similar sounds apart.

What are the signs of auditory processing disorder in adults?

Adults with APD often find it hard to follow conversations in noisy places, keep up with fast speech, understand people on the phone, and locate sounds. They may feel exhausted after listening. It can be lifelong or develop after a head injury or stroke.

Is APD the same as ADHD?

No, but they overlap and can occur together. Both can look like inattention. APD specifically affects processing of sound, while ADHD affects attention, impulse control and activity levels in all situations. Assessment by an audiologist and a psychologist helps separate them.

How is auditory processing disorder diagnosed?

An audiologist first checks hearing with standard tests, then uses specialized listening tests, such as speech in noise and dichotic listening, to measure how the brain processes sound. Testing is usually done from age 7 or older for reliable results.

Can auditory processing disorder be cured?

There is no cure, but symptoms often improve as children mature. Remote microphone systems, classroom changes, listening strategies and auditory training can greatly reduce difficulties at school, work and home.