(Central) Auditory Processing Disorders

What is a Central Auditory Processing Disorder?

(Central) auditory processing refers to the ability of the central nervous system to process incoming auditory stimuli. Therefore, a (Central) Auditory Processing Disorder [(C)APD] is a difficulty in processing what is heard. The difficulty is not due to problems with hearing sensitivity, although (C)APD can co-occur with hearing loss. Generally, children with (C)APD have normal hearing and normal-functioning ears, but have difficulty understanding speech and following instructions. The word “central” refers the fact that the source of the problem is beyond the ears, at the level of the auditory nerve/brainstem/brain.

(C)APD can affect any of the following auditory skills:

• Sound localization and lateralization
• Auditory discrimination
• Auditory pattern recognition
• Temporal aspects of audition
• Auditory performance in competing acoustic signals (e.g. speech in background noise)
• Auditory performance with degraded acoustic signals

What are the symptoms of (C)APD?

Children with (C)APD may display the following behavioural symptoms:

• Difficulty understanding spoken language in competing meessages,
• Difficulty understanding spoken language in noisy backgrounds or reverberant environments
• Misunderstanding messages
• Inconsistent or inappropriate responding
• Frequent requests for repetitions
• Taking longer to respond in oral communcation siutations
• Difficulty paying attention
• Being easily distracted
• Difficulty following complex auditory directions or commands
• Difficulty localizing sound
• Difficulty learning songs or nursery rhymes
• Poor musical and singing skills
• Difficulty with reading and/or spelling
• Difficulty remembering spoken information (i.e., auditory memory deficits)
• Sensitivity to certain noises (e.g., inability to "tune out" a television on in the background while "tuning in" a conversation with a person).

Children who have conditions such as dyslexia, attention deficit hyperactivity disorder (ADHD), autism, autism spectrum disorder, specific language impairment, pervasive developmental disorder, or developmental delay may display some of the above symptoms. (C)APD can co-exist with these conditions; however, generally if your child shows some of these symptoms and has one of the above conditions, the symptoms are most likely due to that condition, and not to (C)APD.

How is (C)APD diagnosed?

(C)APD is diagnosed by an audiologist. There are many different behavioural tests which assess different aspects of auditory processing:

• Auditory discrimination tests: assess the ability of the auditory system to differentiate acoustic stimuli that differ in frequency (pitch), intensity (loudness), and/or duration.
• Auditory temporal processing tests: assess the ability of the auditory system to pick up on subtle timing differences.
• Dichotic speech tests: assess the ability of the brain to separate or integrate information that is presented dichotically (differently to each ear).
• Monaural low-redundancy speech tests: assess the ability of the auditory system to perceive speech that has been degraded in some way e.g. frequency-altered, time-altered, in the presence of background noise. These test materials are presented monaurally (to one ear at a time only).
• Binaural interaction tests: assess the ability of the auditory system to make use of binaural cues (differences between ears of a given signal) e.g. localization, understanding speech in noise.

Diagnostic centres in the Greater Vancouver Regional District offering (C)APD testing:

BC Children's Hospital does not offer (C)APD testing. However, the following sites do provide assessments for auditory processing disorders:

• Surrey Memorial Hospital, Surrey (604) 585-5674
• Sound idEARS Clinic (private) Vancouver (604) 708 9780 Sound idEARS website link

• Northern Sound Clinic (private) Vancouver (604) 221 4688  www.northernsoundhearing.com

Please note that some of the above sites may involve fee per service, and may offer service only to patients living within the geographic area served. Some of the above clinics may require a speech-language assessment and psychoeducational testing prior to (C)APD testing. This list is not exhaustive and it is suggested that you contact the centres to confirm availability of this type of testing.

Information for this page obtained from: American Speech-Language-Hearing Association. (2005). (Central) Auditory Processing Disorders. Click here to view the document.