aid (ād) help or assistance; by extension, applied to any device by which a function can be improved or augmented, as a hearing aid.
hearing aid,
hearing [hēr´ing]
first aid the initial emergency care and treatment of an injured or ill person before definitive medical and surgical management can be secured.
hearing aid a device that amplifies sound to help deaf persons hear, often specifically a device worn on the body.
pharmaceutical aid see under necessity.
| hearing aid n. A small electronic apparatus that amplifies sound and is worn in or behind the ear to compensate for impaired hearing. |
hearing aid,
an electronic device that amplifies sound used by people with impaired hearing. The device consists of a microphone, a battery power supply, an amplifier, and a receiver. The microphone receives sound waves directed toward the person with hearing loss, then converts the sound waves to electrical impulses that are amplified with the aid of the power supply, and the receiver converts the electrical impulses back into sound vibrations. Newer, programmable hearing aids can be customized on the basis of the characteristics of an individual's hearing loss.
hearing [hēr´ing]
the sense by which sounds are perceived, or the capacity to perceive sound; sound waves are converted into nerve impulses for interpretation by the brain. The organ of hearing is the ear, which is divided into the outer, middle, and inner ear, each with its own role. Connecting the middle ear with the nasopharynx is the eustachian tube, through which air enters to equalize the pressure on both sides of the tympanic membrane (eardrum). Called also audition. 
As sound is conducted from the external ear to the inner ear, the sound waves undergo considerable transformation. The tympanic membrane (eardrum), ossicles, and cochlea act as a mechanical transformer to concentrate the sound waves so that they can be picked up by nerve endings in the inner ear and transmitted to the brain.
hearing aid an instrument to amplify sounds for those with hearing loss. There are two types of electronic hearing aids: the air-conduction type, which is worn in the external acoustic meatus, and the bone-conduction type, which is worn in back of the ear over the mastoid process.
Those who have conductive hearing loss can often use any one of the better aids with good results. Patients with otosclerosis will probably need the bone-conduction type of instrument. Those with sensorineural hearing loss (caused by injury to the vestibulocochlear nerve), or a mixed type, may have more trouble selecting a suitable hearing aid and may get less satisfactory results.
Those wearing a hearing aid for the first time should have special training in its proper use. A hearing aid picks up and amplifies all sounds in the vicinity. Often a person whose hearing has declined gradually will have lost the facility to ignore background noises. When one first tries a hearing aid, one's ears will be assaulted by the sounds of passing cars, of doors slamming, of telephones ringing. Training in how to filter out these noises and concentrate on the essential is necessary if the person is to get good results from the hearing aid. For best results, this should be combined with lessons in lipreading.
A cochlear implant can help profoundly deaf persons recognize and interpret various sounds. It does not restore hearing but can improve the quality of life for the deaf.
Those who have conductive hearing loss can often use any one of the better aids with good results. Patients with otosclerosis will probably need the bone-conduction type of instrument. Those with sensorineural hearing loss (caused by injury to the vestibulocochlear nerve), or a mixed type, may have more trouble selecting a suitable hearing aid and may get less satisfactory results.
Those wearing a hearing aid for the first time should have special training in its proper use. A hearing aid picks up and amplifies all sounds in the vicinity. Often a person whose hearing has declined gradually will have lost the facility to ignore background noises. When one first tries a hearing aid, one's ears will be assaulted by the sounds of passing cars, of doors slamming, of telephones ringing. Training in how to filter out these noises and concentrate on the essential is necessary if the person is to get good results from the hearing aid. For best results, this should be combined with lessons in lipreading.
A cochlear implant can help profoundly deaf persons recognize and interpret various sounds. It does not restore hearing but can improve the quality of life for the deaf.
Hearing aids. From Lammon et al., 1995.
hearing aid,
n an electronic device used to amplify and shape waves of sound entering the external auditory canal.
hearing aid, behind-the-ear,
n an electronic device, situated over the ear, for amplifying and shaping sound waves entering the external auditory canal.
hearing aid, eyeglass model,
n an electronic device, attached to the eyeglasses' thickened temple bar, for amplifying and shaping sound waves entering the external auditory canal.
hearing
the sense by which sounds are perceived, by conversion of sound waves into nerves impulses, which are then interpreted by the brain. Also, the capacity to perceive sound. The organ of hearing is the ear, which is divided into three sections, the outer, middle and inner ear. Each plays a special role in hearing. Connecting the middle ear with the nasopharynx is the pharyngotympanic canal, through which air enters to equalize the pressure on both sides of the tympanic membrane (eardrum).
hearing aid
an instrument to amplify sounds for the hard of hearing. These have been fitted to dogs, but are not normally offered in veterinary practice.
hearing tests
are difficult to administer and interpret in any other than laboratory-trained animals or without specialized electronic equipment such as an impedance audiometer or electroencephalograph with which auditory cortical evoked responses can be measured.
hearing dog
a dog trained to respond to sounds such as a telephone ring or door bell; used to assist hearing impaired humans.
hearing aid
Audiology A battery-powered electro-acoustic device that brings amplified sound to the ear to improve hearing, generally worn in the ear. See Hearing loss.
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