The ability to perceive sound, which involves the inner ear and eighth nerve. It involves the movement of stereocilia (little hair-like structures) in the ears, which convert mechanical energy of sound waves into electrical impulses that are then transmitted to the brain.
Several technologies can be used by people with a hearing disability to listen to a TV program or speech. Some devices amplify sounds and others present text captions on the screen or monitor. Captioning systems are ideal for deaf or hard-of-hearing viewers who do not have a cochlear implant.
Device that transmits a wireless signal from a transmitter to a receiver, which is worn by the viewer. It is useful for one-on-one conversations, listening to television and radio. The receiver can be worn in the ear, a neck loop or in a telecoil. It also allows the user to hear the sound directly without interference from electromagnetic fields, which can cause hearing loss. It is available for home use and may be plugged into the television.
Hearing aids vary in size and electronics, but they all perform the same function: They make sounds louder by either acoustic or electronic means. Some have additional circuitry that can be programmed by an audiologist, which allows for a greater flexibility in programming the sound circuits to specific environments. This can reduce problems such as feedback, occlusion and loudness recruitment.
A telecoil, which is a small magnetic coil, is built into some hearing aids to allow users to hear a telephone call without disturbing others and to work in public facilities that have installed audio induction loop systems for public announcements. This includes many train stations, churches, airports and auditoriums. The hearing loop system is activated by the switch on the telecoil of a hearing aid, which operates in either an acoustic (microphone) or electromagnetic (telecoil) mode.