Auditory System Auditory Processing

The hearing mechanism involves a chain of structures, from the outer ear, to the middle and inner ear, and to the brain. Sound must travel through the structures of the outer, middle and inner ear before it triggers a nerve impulse that is sent to the brain. The brain is responsible for the higher-level interpretation of sound known as “auditory processing.”

Auditory Processing - The Human Auditory System

Auditory Acuity vs. Auditory Processing

Auditory acuity is the term used to describe the level of physical functioning of the structures of the hearing mechanism. If the structures are functioning properly, and an individual’s results on a hearing test are within normal limits, then his auditory acuity is intact. However, in some cases, individuals may have difficulty understanding or processing auditory information, even if their physical ability to hear sounds falls within the normal range.

Auditory processing differs from hearing acuity in that it involves a higher level of understanding of sound information in the brain. Once sounds information from the environment has been transmitted through the hearing mechanism and has resulted in nerve impulses to the brain, the brain must interpret and assign meaning to the sounds. This assignment of meaning is termed “auditory processing.” Auditory processing is particularly important in speech, as the brain must:

  • Recognize certain sounds sequences as words
  • Activate the meaning of those words
  • Understand the meaning of groupings of words at the sentence and conversation level.

Problems with Auditory Processing

Individuals who have difficulty understanding auditory information, but whose hearing tests indicate normal hearing acuity, may have problems with auditory processing. These problems are particularly visible when a person is trying to understand and interpret speech. Human speech is made up of a huge variety of speech sounds, some of which can sound very much alike, and consists of rapid transitions from one sound to the next.

Some individuals are diagnosed with Auditory Processing Disorder (APD), also called Central Auditory Processing Disorder (CAPD). This diagnosis refers to a problem with processing and understanding auditory information at the level of the brain, which is not attributable to a hearing loss or other disorder.

Auditory Processing Treatment

Auditory processing treatment usually involves increasing the signal-to-noise ratio in the environment. If the signal (or the desired auditory information) becomes stronger than the noise (the extraneous auditory information), individuals with auditory processing problems often have less difficulty understanding auditory information. This change can be made by:

  • Decreasing background noise, by improving room acoustics or reducing additional auditory input
  • Increasing the strength of the signal, using an amplification device such as an auditory trainer.

Treatment approaches may also target the weakness directly, attempting to improve auditory processing skills.

Resources

Bellis, T. (n.d.). Understanding auditory processing disorders in children. Retrieved January 30, 2010, from American Speech-Language-Hearing Association Web site: http://www.asha.org/public/hearing/disorders/understand-apd-child.htm.

National Institute on Deafness and Other Communication Disorders (n.d.). Auditory processing disorder in children. Retrieved January 30, 2010, from National Institute on Deafness and Other Communication Disorders Web site: http://www.nidcd.nih.gov/health/voice/auditory.asp.