What is Auditory Processing Disorder?
Could an Auditory Processing Disorder Hearing Aid be of use to you? Auditory processing disorder (APD) is defined as a deficit in the ability to interpret and understand auditory information. Simply put, auditory processing is what we do with what we hear. You may also see APD referred to by some professionals as central auditory processing disorder (CAPD) or (central) auditory processing disorder (C)APD. This has to do with differing beliefs on where the difficulties originate in the auditory pathway, but they are all referring to the same core diagnosis.
The Diagnosis of APD is Heterogenous
Symptoms can present in a wide variety of areas of auditory processing, may be present in young children through elderly adults, can occur with normal hearing or with comorbid hearing loss of any type or degree, and can be congenital or acquired. In daily life, APD might present as difficulty with sustained attention, following directions, hearing a noise, or localizing sound, among other possible symptoms. Some research suggests that factors such as chronic otitis media (middle ear infections) in childhood can contribute to APD. APD can also occur as a result of traumatic brain injury. In other cases, it appears to be congenital and without any comorbidities, though some professionals believe these cases of “pure” APD to be quite rare.
How is APD Diagnosed?
APD can be tricky to diagnose because it can present very similarly to other diagnoses, such as hearing loss, attention deficit hyperactivity disorder (ADHD), or learning disabilities. APD is typically diagnosed by an audiologist, though there are other professionals, such as speech-language pathologists (SLPs), who may be trained in diagnostic testing. A multidisciplinary or interdisciplinary team, including professionals such as SLPs, occupational therapists, teachers, and physicians, among others, may also be helpful depending on the presentation and suspected etiology of APD.
A diagnostic evaluation will begin with a hearing test to determine hearing sensitivity and then proceed with a series of tests in different areas of auditory processing, such as localization and lateralization, dichotic listening, auditory discrimination, pattern recognition, and performance with a degraded signal. There are many tests designed to assess APD, and it is important to use a comprehensive test battery with tests in various categories of auditory processing.
These tests are normed by age, and a diagnosis of APD, according to the American Speech-Language-Hearing Association (ASHA) is failure of two or more tests by two standard deviations or failure of one or more tests by three standard deviations. This is crucial to consider because it is possible that adding more and more tests to the battery will result in a diagnosis simply because of the odds rather than actual performance.
Depending on the presentation of the patient, additional age-appropriate tests to assess IQ, language, attention, and phonemic awareness may also be warranted and administered by a qualified professional. Most professionals will not assess for APD before age six or seven because of the auditory maturation that occurs in young childhood. The testing for APD may need to be conducted over several sessions in order to avoid test fatigue, which could result in poorer performance on the specific types of tests. Some professionals also advocate for objective, electrophysiological testing in addition to a behavioral test battery.
Auditory Processing Disorder Treatment
Despite the varied presentation of APD in different patients, likely the most common recommendation is to improve the signal-to-noise ratio (SNR) in as many situations as possible. For some, this might mean preferential seating in a classroom to be closer to the teacher or lecturer. For others, it might mean conducting business in quieter environments without the distraction and degradation caused by background noise.
One way to improve the SNR is through traditional FM systems. An FM system involves a microphone worn by the target speaker and a means to deliver that signal. There are sound field FM systems with speakers strategically placed around a room, which benefits all listeners in the room. A sound field FM system allows the teacher’s voice to be delivered in close proximity to all students in the classroom rather than just those in the front row and can help to combat some of the difficult classroom acoustics. This is the ideal setup for a school classroom, though.
Unfortunately, few schools have the resources to fund this configuration in all classrooms. With a personal FM system, the signal from the microphone would be delivered via the user’s hearing aids, cochlear implant, or FM receivers, which are devices that resemble hearing aids but do not provide amplification in addition to the FM signal.
FM systems are particularly common for children with hearing loss who may need additional support in the classroom or other challenging listening environments. They may also be recommended for children with ADHD or learning disabilities who struggle to maintain attention or follow directions in the classroom.
Newer technology, such as the Roger system from Phonak, is technical “DM” (digitally modulated) and has advanced noise-canceling technology to make sure the signal is very clean and that it is targeting speech. There are certain transmitters that are designed to capture a variety of voices rather than just one (i.e., a microphone that can be placed on a table during a business meeting rather than a single microphone worn by the teacher for a classroom lecture), should the situation warrant this.
The Roger technology is universally compatible with all major brands of hearing aids and cochlear implants as long as a compatible receiver is used. Be aware that these systems can be quite costly; however, most public schools will provide an FM system for children with a confirmed diagnosis of hearing loss or APD, and many employers will offer financial assistance for this type of technology if it is warranted for work performance.
Like FM/DM systems, modern hearing aids aim to capture speech and reduce background noise, so hearing aids on their own can be a viable treatment option for APD. This is a treatment that is more likely to be recommended if the APD is co-occurring with some degree of hearing loss so that binaural amplification is delivered in addition to improving the SNR.
However, “low-gain” hearing aids can be recommended for individuals with normal or near-normal hearing, meaning that the hearing aids would be fit with a minimal amount of amplification with a goal of improving the SNR rather than providing a large amount of overall gain. When APD appears to be co-occurring with hearing loss, it is important to treat the hearing loss first and re-assess the presentation of symptoms.
This is also why the evaluation for APD should always begin with a diagnostic hearing test to ensure that test materials are presented at a comfortable level and factor in any degree of hearing loss. It is possible that hearing aids alone will be enough to account for the difficulty with degraded signals, or if the individual is still struggling, an FM/DM system may be recommended in conjunction with hearing aids for the most challenging listening environments, such as in the presence of loud noise and/or over distance.
What Are The Benefits Of Treating APD?
One advantage to both hearing aids and FM/DM systems is the reduced listening effort required by the individual when the SNR is improved. This can substantially improve performance in school or at work and generally contribute to better learning potential and quality of life for the user. Keep this in mind if you are finding it challenging to get an assessment for or diagnosis of APD for yourself or your child.
Many of the suggestions for remediating symptoms of APD are things that can be implemented without a formal diagnosis or individualized education plan (IEP). Preferential seating, avoiding multi-step directions, musical training, and trying to avoid background noise are all things you can try to implement in your daily life. For example, during mealtimes, make sure the TV or any other sources of background noise are shut off. Sit at the table together and try to make eye contact with the speaker. If the person with APD asks for something to be repeated, try to repeat it verbatim rather than rephrasing. Practicing these strategies can temper the frustration that might occur for both parties when the message is not being received.
Auditory Processing Disorder Hearing Aid Conclusion
If you have concerns that you or a loved one is experiencing symptoms of APD, be sure to consult an audiologist. Not all audiologists are trained to assess and diagnose APD, so you should do some research on providers in your area to see who offers the assessment. You can use tools such as the ASHA ProFind to search by specialty in your state, as well as by age and native language.
Erin Edwards received her Doctor of Audiology degree from Towson University in 2015 and her Ph.D. in Education and Leadership from Pacific University in 2022. She has worked with patients of all ages in a variety of settings and has a specific interest in cochlear implants, the relationship of hearing loss and dementia, and interdisciplinary healthcare.