What we think of as "hearing" is much more than detecting sounds with the ear. Hearing, in fact, happens in the brain. The entire process is referred to as central auditory processing. The Central Auditory Processing Evaluation is a service we provide for children from the ages of seven and up, and for adults. Much more than peripheral testing, it involves a series of specific tests that can serve several purposes: as an evaluation procedure for children suspected of having CAP problems; as a test for a child's auditory strengths and weaknesses; and and as a benchmarking tool to provide a speech-language pathologist with information on progress or development during therapy.
Sometimes children described as inattentive, easily distracted and seemingly unwilling to follow verbal directions may have some level of CAP problems. They may have language disorders, or perhaps not perform to their potential academically.
First an audiogram (hearing test) is performed to determine whether there is any hearing loss. Children with CAP problems often have normal hearing and intelligence. Then a number of other tests are done in order to gather information on particular processing skills.
Binaural tests (involving both ears) help to test the effectiveness of the brainstem function in the child. We take information from one ear and combine it with information from the other ear - a function of the brainstem. Through these, the audiologist can determine how well the child is fusing different information being received from each ear.
In monaural tests, each ear is tested separately. These involve both the cortical and brainstem levels.
The Auditory Figure-Ground tests for problems in hearing sounds over background noise.
To test auditory closure, the audiologist uses the Low Pass Filtered Test. The child hears words that have been altered by removing high frequency information such as consonants. The child is asked to identify the words. This test can help determine which ear is dominant; highlight problems in identifying language when some auditory cues are missing; and recognize difficulties understanding language when there's noise in the background.
A further test, the Competing Sentence Test, takes a look at the cortical region. The child receives a different sentence in each ear and is asked to repeat the softer one, determining an ability for selective attention. Together with the Low Pass Filtered Test, this technique can help pinpoint the particular area of the cortical region where the difficulty lies.
Functional Auditory Tests determine how well a child can perform in short term memory, in the phonetic sounding out of words and in discriminating speech sounds in varying noise conditions.