Auditory Processing Disorders

Seeing Words Speaking Words Thinking Words Hearing Words

AUDITORY PROCESSING DISORDERS

In conversational speech, words flow together in the stream of sound. We perceive distinct words in speech because we have learned to recognize the acceptable boundaries of sounds that each word represents. For example in America, “how ah yuh?” is easily recognized by English speakers as, “how are you?” This ability depends on four functions:

the ability to process language sounds rapidly (speed of processing)
the ability to recognize incomplete or unusual forms of a word (closure)
the ability to attend to one part of a sound pattern (auditory attention)
the ability to understand speech in background noise (figure/ground)

About one in five children have difficulty with one or more of these functions and are determined to have an auditory processing disorder or CAPD (central auditory processing disorder). Auditory processing disorders can render a child functionally deaf to their native language in spite of normal hearing. This is because tones and words are processed in different areas of the brain. Hearing tests determine the ability of the cochlea to pass tone frequencies to the brain. Auditory processing tests determine the ability of the brain to associate meaning with words presented in different conditions.

Pink= Language areas

Auditory processing disorders can be the result of damage to the auditory cortex as a result of infection, inflammation, immune disorders, or trauma. They can also be caused by hearing loss, a lack of language experiences in infancy, or distorted hearing during the critical period of language development. Although the exact timing of this window is unknown, animal research suggests that it probably occurs in the first 6 months of life and is likely lasts for only a matter of days or weeks. Anything that disrupts or interferes with the transmission of language sounds from the ear to the brain during this critical period can result in permanent abnormalities in these circuits.

The most common reason for CAPD appears to be blocked Eustachian tubes during the critical period in which language networks are developing (first 6 months of life). The Eustachian tubes are critical for maintaining ventilation in the middle ear. Blocking these tubes distorts the sound wave as it passes from the tympanic membrane (ear drum) to the cochlea, shearing off the consonants carried in the high frequencies. Eustachian tubes can become blocked from secretions related to allergies or infections, nasal congestion, milk reflux, large adenoids, tumors, or abnormal anatomy.

CAPD creates gaps in the sound stream, much like a skipping record. The brain attempts to repair all gaps in perception by using the context and inserting a “best guess” about what is missing. In neuroscience we refer to this as the “filling in phenomenon.” Unfortunately, the brain often guesses incorrectly, especially if it has limited information about what is likely to have been said in a particular situation, or if there are no other cues to use as guides (e.g. reading lips, gestures, etc). This is why children with CAPD often misunderstand what was said.

It is important to remember that a child with CAPD really does hear something different than what was said. They can not know that you actually said something else when they REALLY DID HEAR IT DIFFERENTLY. This is not a matter of attention or “bad behavior” but a true perceptual illusion. Since this process of “filling in” is automatic and unconscious, individuals with CAPD are not aware that they are hearing something different than what was said. It is important to remember that IT IS VERY FRIGHTENING TO THINK THAT YOUR EARS ARE PLAYING TRICKS ON YOU. Therefore children may become very angry or stubborn about what they think they heard. Do not argue about it, but it helps to mention that everyone’s brain fills in things wrong from time to time and that there are ways to know when we didn’t hear something right (ask the speaker to repeat what they said, repeat what you heard and ask if this is correct, etc.)

A CHILD WITH CAPD:

may repeatedly ask, "what did you say?"
may ignore or misunderstand spoken directions
may seem resistant or stubborn

tends to rely on movement and gestures to guess the meaning of what you said

will understand more when you slow down and speak clearly

may have articulation problems

may have difficulty using the past, future, or imperfect tenses

tends to have difficulty understanding sequences of events or time related concepts

tends to misunderstand the meaning of expressions, tone of voice, or gestures

tends to prefer facts to stories and may have difficulty understanding pragmatic language

exhibits symptoms of vestibular problems

may prefer to be alone (in order to limit the amount of speech they must process)

Sensory processing areas of the brain

IDENTIFYING AUDITORY PROCESSING DISORDERS

Auditory processing disorder is a perceptual disorder specific to the comprehension of spoken language. It does not imply (or rule out) that there is a hearing loss, and conventional tests of hearing are not designed to identify auditory processing disorders. Only a test that requires a child to repeat words and sentences in different conditions can expose auditory processing problems.

Tests of auditory processing functions must be presented in the child’s native language and must examine the child’s ability to perform four basic functions: understand speech that is slightly muffled (auditory repair), understand speech when there is background noise present (figure/ground), process language at the rate it is spoken (speed of processing) and use context to repair gaps in the perceptual field. We use the SCAN test because it meets these criteria and helps us determine whether an individual has the necessary perceptual skills for accurate speech comprehension.

Once we have determined which perceptual skills are impaired we can then design an appropriate intervention program. Treatments may include learning visual repair strategies, improving vocabulary and syntax knowledge, increasing speed of processing, and improving the pragmatic understanding of spoken and non-verbal communication.

STRATEGIES THAT IMPROVE THE COMPREHENSION OF SPEECH

· Use gestures, drawings, or objects to demonstrate what you mean

· Speak clearly, slowly, and repeat important words or concepts

· Be specific and concrete in your instructions and explanations.

· Do not assume that the child should know or understand something

· Ask the child to tell you what they heard

· Keep explanations short and to the point

· Point out how things are related

· Be sensitive to the fact that cognitive fatigue occurs when children with CAPD are listening or reading. You must provide frequent (short) breaks

· Do not misinterpret cognitive fatigue or inattention as ADD or a lack of motivation

· Respect the child’s need for vestibular stimulation

· Respect the fact that the child can not process what you say if they are looking at your face while you are explaining something new or difficult

· Respect the fact that the child has vestibular dysfunction and will have problems in these areas:

1. remaining seated or sitting with both feet on the floor

2. understanding directions if they are verbal

3. staying still or staying quite in class

4. calming down when frustrated or angry

5. remembering a sequence of events, actions, or directions without cues

6. handwriting, written expression and reading comprehension

INTERVENTION METHODS FOR CAPD

Interventions for CAPD depend entirely upon which of the four auditory skills are impaired and how delayed the child is in language development. Some of the more effective therapies include:

Cognitive therapy (helps the child understand what might have been said and implied by words, actions, gestures, facial expressions, and body language)
Earobics (computer games by Cognitive Concepts, designed to improve auditory memory, auditory segmentation skills, and phoneme perception)
Auditory attention training using video tapes of stories (child is cued by stopping the tape and asking them to repeat names, dates, places, and sentences after important cue words like “since,” “so that,” “that’s why,” etc.)
Vocabulary building and grammar skills training (this improves a child’s understanding of what might have been said in different situations)
Auditory comprehension training (child draws pictures of the sequence of events as they listen to stories on tape)
Field trips (helps child learn how to use language to give and receive information and increases their pragmatic understanding of cultural activities; adult explains in concrete terms the processes, meaning, and significance as the child investigates hospitals, car washes, stores, museums, art galleries, grave yards, bowling alleys, cultural events, etc.)
Goal directed group play (playing board games, building something, or creating something with one or more partners)
Vestibular therapy (exercises and activities designed to move the head in space, increase perception of limbs and body movement, track moving objects, etc.)
Auditory memory training (child learns to associate words with pictures, use visual imagery and draw meaning instead of relying on language)
Premotor activities (child learns new motor sequences through games, sports, music, dance, etc.)