What is auditory processing disorder?

Auditory processing disorder (APD) is a condition where the brain doesn’t properly translate the meaning of sounds. 

Auditory processing disorder is considered a hearing impairment—not a hearing loss, notes says Leah Light, AuD, the founder and director of the Brainchild Institute in Hollywood, FL.

Hearing loss is a disorder of the peripheral auditory system (originating in the ear) whereas APD is a disorder of the central auditory system (originating in the brain). For this reason, APD is sometimes referred to as central auditory processing disorder.

Affects all ages

The Nemours Foundation estimates that 5 percent of school-aged children have this condition. And while it’s often associated with childhood, APD affects people of all ages.

“There are many adults suffering from auditory processing disorder,” says Dr. Light.  

What are symptoms of auditory processing disorder? 

According to diagnostic guidelines from the American Academy of Audiology, some of the common symptoms of auditory processing disorder include: 

• Feeling like you can't hear even when your hearing test is normal
• Struggling to hear or easily distracted in noisy situations
• Struggling to detect where sounds are coming from (localization)
• Difficulty following multistep directions
• Startling easily
• Difficulty participating in conversations—that is, not responding to questions, misunderstanding what people said, not following jokes or stories, or having trouble with straightforward instructions.
• People with APD may frequently say “What?” after a question or ask for it to be repeated. 
• Difficulty concentrating and a lack of focus. 
• A lack of appreciation for music, as well as a lack of musical abilities. 

Many of these symptoms are also often present with other disorders, notes the American Speech-Language-Hearing Association (ASHA).

“As audiologists, we say auditory processing disorder can coexist with other types of problems like ADHD or language processing [disorders],” says Dr. Light. 

What causes auditory processing disorder? 

The cause of auditory processing disorder is not always known, says Dr. Light. The disorder may be linked to some of the following factors:

• Prenatal issues or a difficult birth — Sometimes, taking a detailed case history will reveal a low birth rate or other issues that may be the root cause of this condition, says Dr. Light. 
• Other illnesses and conditions — Head trauma and chronic ear infections may be related to this condition, per the Nemours Foundation, as well as degenerative conditions.
• A family history — There may be a genetic component to this condition.
• Age — Changes to the brain related to aging make it harder to process information as it’s spoken, says Dr. Light.  
• Traumatic brain injuries — Head or blast injuries can lead to APD, says Dr. Light. VA research has shown that veterans who suffered blast injuries are at risk of auditory processing disorder.
• Neurotoxins — Exposure to things like heavy metals and organic solvents are linked to APD, notes ASHA.

Diagnosis can be tricky

A person with APD can perform perfectly on a hearing test that just involves listening to beeps in an otherwise silent environment. Medically, this is sometimes referred to as "near-normal hearing thresholds."

This can make it tricky to detect and diagnose correctly. Also, young children may not possess the verbal and communication skills to complete the full battery of tests that audiologists perform, says Dr. Light. 

While the diagnosis is made by an audiologist, often a team of specialists—including speech-language pathologists and psychologists—play a role in assessing symptoms and developing a treatment strategy, per the American Academy of Audiology.

There is no standardized way to test for APD, so a number of tests may be necessary. To diagnosis APD, audiologists and other experts will: 

• Take a thorough case history — Remember, some of the risk factors potentially leading to APD can occur when in utero. A detailed history can be helpful, therefore. An audiologist will ask questions about circumstances when hearing is difficult. With children, insight from other professionals (teachers, psychologists, and so on) can also be helpful, as well as details from parents.  
• Perform hearing exams — A specific battery of tests are used to assess auditory processing function, Dr. Light says. Before starting these tests, audiologists check for any issues with the ears (e.g., eardrum abnormalities) that need medical attention, as well as checking hearing sensitivity, she says. 
• Perform behavioral and brain function tests — A number of tests may be performed, depending on your care team. They may include (but aren't limited to) auditory discrimination tests to determine how you differentiate similar sounds and dichotic speech tests to test your ability to interpret and differentiate sound coming to each ear separately.
• Administer electrophysiologic tests — In babies and in situations where typical testing won't work, tests that measure how how the sound is delivered from the ear to the brain may be used. These include auditory brainstem response tests. They are painless and non-invasive.

Treatment for APD

There’s no pill or quick fix available when it comes to APD, says Dr. Light. However, there are frequently used treatment strategies, including: 

Auditory training

Just like physical therapy helps people regain strength and function, auditory therapy helps people improve their hearing. Depending on the specific type of disorder, this might be helping people distinguish between phonemes, or common sounds, like “pat” and “bat,” to recognize where sound is coming from, or focus on other hearing-related skills, per ASHA. Some programs are self-taught, such as LACE, which stands for Listening and Communication Enhancement.

Low-gain hearing aids

Low-gain or mild-gain hearing aids are normal hearing aids that are programmed to slightly increase the volume of speech while reducing background noise. While more research is needed, there are many anecdotal reports of low-gain hearing aids helping both kids and adults in noisy situations. 

Assistive listening technology with or without hearing aids

With a FM/DM system, a speaker (such as a teacher) wears a wireless microphone that transmits sounds to the headset or hearing aids of the person with APD. Often, it’s helpful in the classroom, since then “the teacher’s voice goes directly into the child’s ear, without getting polluted by other noises in the room,” says Dr. Light, who says the devices can be a helpful tactic for dealing with background noise.

However, a remote microphone also makes it harder for a child to hear fellow nearby students, so it can be frustrating to use them. Sometimes, both a low-gain hearing aid and an remote microphone are used. "The listener can experience the best of both worlds in many cases," states the Auditory Processing Center in their article on the topic.

Developing compensatory strategies

As well, there are ways to learn strategies that help people work around the processing challenges, says ASHA, such as learning how to use mnemonics to recall information. Others may find it highly beneficial to learn lipreading.

Environmental changes

Asking people to speak slower, using notes, and opting for written over verbal instructions may be helpful, says the Nemours Foundation. Even a new seat—in the front of the classroom, instead of the back—can be a meaningful change. 

The profound impact of having untreated APD

"APD in children causes academic struggles for if a child cannot focus on a teacher’s voice in a noisy classroom or becomes exhausted during the day due to the increased auditory effort of listening," explains Donna Moore in her dissertation on "The Use of Mild Gain Hearing Aids for Adults with Auditory Processing Difficulties."

Adults experience similar challenges. "They may be unable to function well in jobs due to auditory fatigue or be mislabeled as unable to perform and multitask because they have difficulty following multistep directions delivered [via speech]," Moore writes. This may lead to social isolation or anxiety.

Subtypes of auditory processing disorders

There are different types of auditory processing problems, such as a decoding deficit, an auditory integration deficit, or an output organization deficit, that all sit under the umbrella of auditory processing disorder, Dr. Light explains.

“Each of these problems points to a different area of the brain that might be underdeveloped. We try to do deficit-specific interventions to target and stimulate that area,” she says. 

Similar but not the same: Hidden hearing loss

Some people do not have auditory processing disorder, but have many of the same symptoms. This problem originates in a different part of the brain and is known as hidden hearing loss.

If you're struggling to hear but have normal hearing

Visit a hearing clinic near you for a full test and help figuring out if you might have hearing loss, hidden hearing, APD, or something else.