Hearing Aids By The Association Of Otolaryngologists Of India- Hearingequipments

Description

Hearing aid is a device that improves hearing. It enables deaf people to understand speech, use the telephone and enjoy music.
In 1876 Alexander Graham Bell the noted American scientist while experimenting to develop a hearing aid to help deaf children, invented the telephone. The principle employed formed the model for electric hearing aid.
COMPONENTS OF HEARING AIDS
Electronic hearing aids are essentially small telephone or public address system. These consist of a microphone, an amplifier and a receiver. The 'MICROPHONE' transforms the acoustic signal (ie the sound of speech, music etc) to an electrical current (signal).
The 'AMPLIFIER' increases the power of the signal.
The 'RECEIVER' converts the electrical impulses (signal) from the amplifier into sound energy.
Therefore the microphone picks up the sound, amplifier amplifies (increases) the sound and to some extent modifies the sound and finally the listener hears the sound through the receiver, fitted into the ear with the help of ear mould.
All these components require a power source, which is provided by batteries.
TYPES OF HEARING AIDS
According to size and shap
Body worm aid
Behind the ear aid(BTE)
In the ear aid (ITE)
In the canal aid (ITC)
Completely in the canal aid (CIC)
Air condition aids and bone conduction aids
According to technology
Analog
Digital
BODY WORN AIDS – The microphone, amplifier and batteries are incased in a small box, which is clipped with the pocket of shirt or with the vest. A length of wire connects the amplifier with the receiver, which in turn is attached to the ear with an ear mould.
BEHIND THE EAR (BTE) AIDS – These aids fit behind the pinna an are held in place by a hook shaped rigid tube fits over the pinnia. A soft polythene tube is connected to this rigid hook shaped tube and to the ear mould fitting into ear canal.
IN THE EAR AID (ITE) – This type of aid consists of a signal piece. The electronics is places inside a shell that fits in the patient’s ear canal. The shells are individually prepared according to the size a shape of the external ear canal of the patient.
IN THE CANAL AID (ITC) – protrude slightly from the ear canal.
COMPLETELY IN THE CANAL (CIC) AIDS are placed completely with in the ear canal, only a clear filament protrudes from the ear canal to help removal of the aid.
SPECTACLE AID – The electronics of the hearing aid is constructed inside the hollowed spectacle frame.
AIR CONDUCTION AIDS – Amplifies the sound and brings it directly to the ear canal by a ear mould. The sound reaches the ear drum after traveling through the air column in the external ear canal.
BONE CONDUCTION AIDS – These aids bring the amplified sound waves as vibrations directly to the bone behind the ear. The bone transmits the vibrations to the nerves of hearing (cochlea and auditory nerve)
ANALOG AIDS – This type of aid is already discusses in “components of hearing aid” section. This type of aid is widely used. These aids are less expensive, but has disadvantage of having internal noise and less efficient frequency response.