Hearing Impairment

Hearing impairment is the decreased ability to hear and differentiate sounds. Impairments in hearing can be either related to sound intensity, frequencies (high or low tones) or both, and may differ by ear. Some impairments exist since birth, while others are acquired during the process of aging, or as a result of injury or disease.  

Several problems can lead to hearing loss. The outer or middle ear may block the conductance of sound; sensory nerves or cells of the inner ear may be damaged; or the central nervous system auditory functions may be impaired, so that the perception of sound is not transmitted properly along auditory pathways or processed correctly.

Nearly 100,000 people worldwide have received cochlear implants to improve hearing loss caused by damage to sensory cells or nerves of the inner ear. Cochlear implants bypass damaged portions of the inner ear and directly stimulate the auditory nerve.

• Cochlear Implants
  

Reviewed April 2, 2012
Jaimie M. Henderson, MD
Director-at-Large, International Neuromodulation Society, 2011 - 2014
Associate Professor of Neurosurgery, and, By Courtesy, of Neurology and Neurological Sciences; Robert and Ruth Halperin Faculty Scholar; Director, Stereotactic and Functional Neurosurgery; Co-Director, Neural Prosthetics Translational Laboratory; Stanford University School of Medicine, Stanford, California, USA

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