Auditory Processing Disorders

This web page was made to be a resource to help parents, teachers, and students obtain a better understanding of auditory processing disorders. The goal was to present information on auditory processing in an easy to read form with minimal technical jargon so that anyone can read the following information and obtain a better understanding of auditory processing disorders.

Lets start our discussion of auditory processing disorders with a quick overview of the auditory (hearing) system. As we all know, sound travels through the air as an acoustic signal to the eardrum where the acoustic energy is converted to mechanical energy and transmitted to the cochlea via the eardrum and the 3 small bones (ossicles) in the middle ear.

The cochlea is the first component of the amazing neurological system that gives us hearing. The cochlea is the incredible biological transducer that converts the mechanical representation of the sound coming from the eardrum to the encoded electrical signal that is sent upwards to your brain via a system of neurological "wiring" that we will refer to as the auditory system.The illustration to the right shows the major components of the auditory system for one ear.

As you can see from the simplified diagram of the neurological portion of the auditory system, the auditory system is complex with many nerve connections and structures within your brain working together to transmit the signal coming from your cochlea up to the brain. Not only does your auditory system send information about what you are hearing up to your brain, your brain is also constantly sending signals down neural pathways to control the function of lower portions of the auditory system such as your cochlea.

Humans are not born with a fully developed auditory system. Each year as a child gets older, the neurological components of their auditory systems develop, and the function of their auditory systems improve. Fortunately, auditory system development appears to occur at a fairly predictable rate with most children, and that is what most of the commonly used auditory processing tests are based on. Most auditory processing tests require the child being tested to perform a task that they should get better at each year as they get older, and then the child's performance on the test is compared with statistics to the performance of a large group of children of the same age, that were given the same test in exactly the same way. If the child's performance on the test is significantly poorer than the performance of other children of the same age, then we typically assume that the development of portions of the child's auditory system may be delayed. Poor performance on the tests could also be an indication of damage to parts of the auditory system. Damage to the auditory system could occur with head injuries, strokes, or other traumatic events that could cause damage to structures within the auditory system. Fortunately, the theory that auditory processing problems may be related to delayed development of portions of the auditory system appears to be true in many cases because testing the children annually over a number of years often suggests improved auditory system performance over time and that quite a few kids with auditory processing problems appear to "grow out of it" as they get older.

Hearing loss versus auditory processing disorders:

A frequent point of confusion when trying to explain auditory processing disorders to someone is the difference between having an auditory processing problem versus having a hearing loss.

A person has a hearing loss when sounds have to be louder than normal in order to be heard.

The illustration to the right contains a graph called an audiogram which is used to display the results of a pure tone hearing test which is the most common means of quantifying someone's ability to hear (hearing sensitivity). A pure tone hearing test is performed by determining how loud each of a series of tones of different frequencies have to be before the person being tested can detect the tone.

The audiogram to the right shows the pure tone hearing test results for an individual that has a significant hearing loss for higher frequencies in both ears. This individual's hearing test results show that they can hear the low frequency (low pitch) test tones of 250 thru 1000 Hz at very low (quiet) loudness levels of approximately 5 to 10 dB (decibels) in both ears, and that the higher frequency test tones have to be much louder at levels as high as 65 dB before they can detect the higher frequency test tones. A child should be able to hear all of the test tones listed on the top of the audiogram (250 thru 8000 Hz.) at a loudness of approximately 15 dB or less. If any of the test tones have to be louder than 15 dB before the child can detect the tone, then they have hearing loss for that particular frequency of sound. A child that can hear all of the test tones at approximately 15 dB or less is considered to have normal hearing sensitivity.

The letters typed on the audiogram are an attempt to show the approximate frequency and how loud the different sounds in speech are at approximately 3 feet from the speaker's mouth. As you can see from looking at the audiogram above, someone with this particular hearing loss would not be able to hear higher frequency speech sounds like /p/, /h/, /g/, /ch/, /k/, /sh/, /f/, /s/, and /th/, which will make understanding speech difficult for this individual. Hearing aids could be used to make the frequencies of sound that they have difficulty hearing (1500 Hz and above) louder for them which would help them understand speech better. Hearing aids are not typically used with auditory processing problems because the person with auditory processing problems typically has normal hearing sensitivity.

Hearing loss is usually considered a peripheral hearing disorder because most hearing losses are due to problems in the outer, middle, or inner ear (cochlea), versus central auditory disorders which are due to problems somewhere higher up in the auditory system.

One of the first tests to be performed in an auditory processing evaluation should be a pure tone hearing test to rule out peripheral hearing disorders (hearing loss).

What is an auditory processing disorder?

An auditory processing disorder is when a person that has normal hearing sensitivity has difficulty hearing and/or understanding speech. Auditory processing disorders are thought to be caused by developmental delays, or in some cases, damage to portions of the complex neurological system that allows us to hear. People with auditory processing disorders tend to have greater than normal difficulty understanding speech in less than ideal listening environments such as in areas where there is excessive background noise.

Auditory processing disorders make academic success difficult for children because much of their day in the classroom is spent listening to information and instructions presented verbally in listening environments that may be less than ideal.

Auditory Processing Disorders versus Attention Deficit Disorders:

Most auditory processing tests require the person being tested to listen intently and repeat back words, sentences, numbers, or tone patterns that they hear through headphones. The tests require that the student sit quietly and pay very strict attention to uninteresting stimuli for long periods of time, so just by their nature, auditory processing tests tend to also have the unwanted effect of being a test of the person's ability to stay focused and pay attention in addition to being auditory processing tests. Stated in different words, people with attention deficit disorders may score poorly on auditory processing tests simply because they have difficulty maintaining the high level of attention required to obtain normal scores on the long, tedious auditory processing tests. Sometimes it is obvious during the auditory processing evaluation that the child being tested cannot stay on task during the tests, but some forms of attention deficit disorders may not be as apparent.

We must be very careful to make sure that children with attention deficit disorders are not mistakenly diagnosed with an auditory processing disorder because the child may then miss the opportunity to try proven treatments for attention deficit disorders that could have helped them significantly. It should also be kept in mind that some children may have attention deficit disorders and also have auditory processing disorders at the same time. If you have any reason to suspect that your child may have some form of an attention deficit disorder have them evaluated by a qualified professional.

Interpreting test scores and diagnosis of an auditory processing disorder.

Explaining the auditory processing test scores a student obtained on the tests is often a point of confusion because most most people do not use statistical terminology on a daily basis. Basically, the score a student obtained on an auditory processing test shows how well they did in comparison to a big group of students of the same age that were given the same test in exactly the same way. Many tests give scores in percentiles which are usually pretty easy to explain and understand. If you obtain a score at the 25th percentile then you did as good as, or better than 25% of the group of people you are being compared against. The 50th percentile is the mean, or kind of the average guy, so a score at the 50th percentile is actually a good score on an auditory processing test.

Test scores are often described in terms of standard deviations from the mean. On the auditory processing tests I am currently using, plus or minus one standard deviation from the mean is definitely within the normal range, or expressed in percentiles, a score at the 16th percentile or higher is within the normal range. Scores that fall between one and two standard deviations below the mean, or from the 15th percentile to the 3rd percentile are considered to be in the borderline range. In order for a score to definitely be considered abnormal, it has to be 2 standard deviations below the mean, or expressed in percentiles at the 2nd percentile or lower.

When reporting test scores I typically say a score is borderline or below the normal range and should merit attention when it falls below the 16th percentile, but by true definition, a score is not officially indicative of a disorder unless it is at the second percentile or lower.

The American Speech\Language, Hearing Association (ASHA) guidelines for diagnosis of an auditory processing disorder state that the person being tested must score 2 standard deviations below the mean (at the 2nd percentile or lower) on two tests, or 3 or more standard deviations below the mean on a single test to obtain the diagnosis of an auditory processing disorder.

If for example a student obtains scores at the 5th percentile on two of the auditory processing tests, they do not officially meet the criteria to be diagnosed as having an auditory processing disorder, but the test scores suggest that they probably do have difficulty with some aspects of auditory processing, so I typically make recommendations to help and monitor the student in the classroom even though they did not officially meet the requirements to be diagnosed as having an auditory processing disorder.

How do we help someone with an auditory processing disorder?

One of the simplest ways you can help someone with auditory processing problems or hearing loss is by providing them with the best possible acoustic signal. When someone is talking their speech has to travel through the air as sound energy to the listener's ears. As the speech signal travels through the air it progressively gets weaker and the distinctions between different speech sounds become less pronounced. Pretty much without exception, the closer you can get to the person that is talking, the easier it is to understand what they are saying.

Another way to make your speech easier to understand is to remember to face the people you are talking to so that your speech travels in a straight line to the listener's ears. For example, when the teacher is facing towards the board and talking, their speech signal is going to be degraded significantly as it hits the board and is reflected back into the classroom to the listeners.

Try to remember to slow down your rate of speech a bit if you tend to talk fast. People that talk fast are typically more difficult to understand, especially if the listener has hearing loss or auditory processing disorders.

Keep in mind that much of what we hear actually comes from what we are seeing. Your brain makes use of the visual information it is getting from your eyes to help arrive at an interpretation of what you are hearing. People who do not look at and focus on the person that is talking are missing visual information that could help them interpret what is being said more efficiently. A form of direct remediation that may help children with auditory processing disorders and hearing loss is to work with them on "active listening skills" such as always looking at the person that is talking and trying to remain mentally engaged in the conversation or topic at hand. Tactics that keep the student with auditory processing problems actively engaged in classroom lectures and discussions as much as possible are an obvious way to help them succeed.

Classroom accommodations:

The term "classroom accommodations" is frequently used to describe specific strategies that have been devised to help a student overcome specific difficulties they have in the classroom. Specific areas of difficulty for the student are identified and then strategies to help the child with the specific areas of difficulty are devised. For example, written instructions to perform an assignment could be provided for a student that has difficulty following verbal directions. Giving a student preferential seating so that the student is as close to teachers as possible is also an example of a classroom accommodation that is frequently recommended for students with auditory processing disorders.

There are many compilations of "classroom accommodations for auditory processing disorders" that people have put together available online. Following is a link that you can click to download a typical list of classroom accommodations that you can read over to get some ideas that you may be able to use to help your child or student.

Classroom Accommodations

FM systems:

Use of an FM system may be beneficial for a student with auditory processing disorders. There are many variations of FM systems\classroom amplification systems available today, but the overall function of an FM system is to deliver the teacher's voice to the students ear at a loudness level significantly greater than that of the background noise in the classroom (improved signal to noise ratio), and to help minimize the degradation of the speech signal by reducing the distance the teacher's voice has to travel through the air from the teacher's mouth to the student's ears.

It may be recommended that a student try an FM system in the classroom on a trial basis if the student meets certain criteria in terms of their performance on the various auditory processing tests. FM systems can be very beneficial for students with hearing loss, some types of auditory processing disorders, and even students with attention deficit disorders in some cases, but unfortunately most school districts have limited resources in terms of the types and quantities of FM systems they may have available due to funding limitations.

Therapies for auditory processing disorders:

The subject of direct therapies for remediation of auditory processing disorders is a complex and controversial topic. Many therapies have been developed over the years, but determining if the therapy programs are truly beneficial enough to be considered a good use of the student and family's valuable time and resources has been difficult.

I suspect that one of the factors that has made it difficult to develop effective therapy programs for auditory processing disorders is that as you can see from the preceding diagram of the auditory system, the human auditory system is made up of many different structures where there could potentially be problems, plus the auditory system is controlled by the brain in yet to be understood ways, and there are many other factors such as cognitive function and language skills that are probably involved in the complex process known as auditory processing, so it is quite likely that there may be a variety of causes for auditory processing disorders, some of which may be helped with direct therapy programs and possibly some not. Hopefully future research will aid in developing tests that help pinpoint more specific auditory processing deficiencies so that more specific individualized therapies can be recommended with confidence that they will be effective.

"Earobics" is one of the commercially available therapy programs for auditory processing disorders that has become popular, and it is even available in an inexpensive home version. Earobics is available in several versions for different ages and can be purchased from online vendors such as Amazon and christianbook.com. Earobics is an inexpensive way that you can try a form of direct therapy for auditory processing disorders at home to see if you think it is beneficial for your child. There are also several other commercially available therapy programs that come in home versions that you can try, and there are professionals that offer various therapy programs for auditory processing disorders in a clinical setting in some areas.

 

Written by:

Brent Bowman, Au.D., CCC-A, Audiologist