BACKGROUND: Miss America 1995, Heather Whitestone McCallum, was the first woman with a disability to win the title. She is also one of a growing number of hearing-impaired individuals to opt for bilateral cochlear implants -- one in each ear. There are more than 3,000 bilateral recipients worldwide, and the majority of cochlear implant clinics in the United States have performed at least one bilateral surgery. This provides a major advantage, especially for children with hearing loss, enabling them to grow up learning to hear their own voice, thereby helping them to develop normal speech patterns.
HOW IT WORKS: Cochlear implants are miniature devices designed to mimic how the inner ear works by converting sound waves into electrical impulses carried to the brain. Unlike hearing aids, which simply amplify sound, cochlear implants are much more complicated. Composed of two parts, the devices simulate hearing by picking up sound through an external microphone located behind the ear and transmitting sound as electrical signals across the skin to an implanted receiver. The implanted device sends microcurrents directly into the auditory nerve, producing the sensation of hearing in the brain.
ABOUT HEARING LOSS: Most people's hearing begins a gradual decline at 20 years of age, depending on a variety of factors, but others are born deaf (congenital deafness). Conductive deafness is caused by the failure of three tiny bones in the middle ear to pass along sound waves to the inner ear, or the eardrum's failure to vibrate in response to incoming sound waves. Certain diseases can cause nerve deafness, blocking electrical impulses before they reach the brain, so incoming sound can't be "translated." Loud noises, such as explosions or gun shots at close range, can damage the ear's various mechanisms, as can disease or trauma, such as a perforated eardrum.
WHAT IS SOUND? Sound waves are pressure waves: the result of a vibrating object that creates a disturbance radiating outward through the surrounding air. These vibrations disturb the molecules that make up the air. The air molecules push closer together as the object moves one way -- an effect known as compression -- and then create a space between themselves and the vibrating object as it moves the other way, called rarefaction. The motion disturbs the neighboring molecules in turn, creating an outward ripple effect, much like a stone cast in a quiet pond will cause waves to ripple outward from the spot where the stone hit. So sound waves travel in repeating patterns of compressions and rarefactions.
The Acoustical Society of America contributed to the information contained in the TV portion of this report.