What is Auditory Processing Disorder (APD)?
Do you find yourself or your child struggling with hearing in background noise? Do you or your child have difficulty with sounding out words while reading or challenges with spelling? If so, you may not have a problem with your hearing, per se. Rather, you may have difficulty with processing the auditory sounds you hear.
Auditory processing is “what our brain does with what we hear” (Jack Katz, Ph.D.). Our inner ears (cochlea) contain sensory hair cells that help to amplify and convert the mechanical energy of sound into electrical impulses that travel along the auditory nerve, which traverses through the brainstem into the auditory cortexes in both hemispheres of the brain. Both the right and left hemispheres of the brain have different functions in processing the auditory signal it receives. The left hemisphere is responsible for the speech and language processing of the auditory signal it receives. The right hemisphere is responsible for the acoustic contour and pitch pattern processing of the auditory information it receives. Both hemispheres communicate with one another via the corpus collosum, which is a thick band of neural fibers connecting both hemispheres together.
In auditory processing disorders, there is a dysfunction along the central auditory nervous system pathway that causes a disruption in how the brain receives and/or processes the sounds it receives. Simply put, this disruption causes a breakdown in the brain’s ability to piece together the acoustic puzzle correctly. While most individuals with APD have normal peripheral hearing ability, some individuals with hearing loss may also have difficulty with auditory processing. Furthermore, APD can co-exist with Attention Deficit/Hyperactivity disorder (ADHD), Autism Spectrum Disorder (ASD), Gifted Intelligence, Specific Impairment in Reading (Dyslexia), and underlying anxiety problems.
The aim of this blog is to briefly highlight the various kinds of APDs that are diagnosed. Individuals may be diagnosed with one category or multiple categories that exist along the APD spectrum. If you are interested in a more in-depth discussion regarding APD, we recommend that you purchase the book by Teri James Bellis, Ph.D., “When the Brain Can’t Hear: Unraveling the Mystery of Auditory Processing Disorder”, which can be found on Amazon.com.
Auditory Decoding Disorder aka Auditory Phonological Processing Disorder
Decoding is defined as how well the brain quickly and accurately digests speech. Humans can decode speech both on an auditory level and a visual level. The easiest example of decoding is when we are learning how to read as young children. In the beginning stages of reading, youngsters learn that individual sounds are linked with the individual letters (orthographic symbols) that make up a word. For example, the word mat is broken down into m-a-t. The smallest unit of sound is known as phonemes. When learning to read, learn that we can manipulate phonemes to create new words. Individuals with auditory decoding difficulty cannot perform this process quickly and automatically. Auditory decoding deficit is very commonly associated with individuals who have Dyslexia, which is a phonological processing disorder. During an APD test battery, the individual will hear small units of sound and may be asked to blend those sounds into a word, which is known as phonemic blending. Another test used is Elision (phonemic segmentation), where the individual will hear a word and be asked to repeat a word with the instructed sound to be deleted. For example, “Say the word, “mat”. Now say it again without the “m”, and the new word is “at”. Difficulty with decoding skills can underly reading and spelling problems.
Auditory Tolerance/Fading Memory Disorder
Auditory tolerance is when an individual struggles with their ability to understand speech embedded in competing noise. The most common complaint is “I have difficulty hearing my teacher in a noisy classroom.” These individuals need the target voice to be louder above the noise floor to help them be able to extract the key auditory information they need to hear. Auditory tolerance issues commonly co-exist with individuals who have ADHD, ASD, or anxiety symptoms. During an APD test batter, the individual will be presented with a list of words (to each ear separately) with competing background noise. Individuals who have difficulty with hearing speech in background noise may also have a co-existing auditory decoding disorder, which would need remediation first before speech understanding in noise can improve.
Auditory fading memory is when individuals have difficulty with the short-term auditory memory loop. This means that they have a difficult time with keeping the auditory information they heard in their short-term memory storage area and are unable to retrieve the information quickly enough to use it. During an APD test battery, the individual will be given a sequence of numbers or words that need to be repeated back in the same order they heard it. Individuals with auditory memory problems may also have associated working memory issues that are best to be evaluated by a clinic psychologist during a comprehensive neuropsychologic evaluation.
Auditory Integration Disorder
Auditory integration is the brain’s ability to take the auditory information it receives from both ears and piece together to make a whole puzzle. When testing for integration problems, the audiologist will instruct a patient to listen to auditory information given through both ears simultaneously (i.e., two words, one word given in each ear at the same time) and the individual needs to verbalize the two items they heard. This process is known as dichotic integration. Individuals who have integration difficulties often also have difficulty with auditory decoding and auditory tolerance fading memory. This is the most difficult APD to treat. Poor integration skills can lead to difficulty with reading and language comprehension. Auditory integration difficulties co-exist with Specific Impairment in Reading (Dyslexia) and Specific Impairment in Writing Expression (Dysgraphia) and may have an associated motor coordination deficit. Motor coordination difficulties warrant an evaluation with an occupation therapist.
The good news is that APDs are very treatable with the right therapy approach. Our clinic has a variety of therapy interventions to help remediate specific auditory processing problems. Depending on the severity of the APD, we will also refer to other local specialists such as speech-language pathologists, educational therapists, occupational therapists, developmental vision therapists, executive function coaches, and/or family therapists. After all, it sometimes takes a village to help solve a problem.
We hope you enjoyed reading this blog highlighting the most common APDs we see in our clinic. If you believe that you or your child has difficulty with auditory processing, please contact our office for an appointment. Our clinic will evaluate children and adults for APD in the age range of 5 years to 50 years old.