Conventional Analog Hearing Aids
All hearing aids are comprised of three basic components- a microphone which picks up the sound and changes it into electrical energy; an amplifier which makes the electrical signal larger (sound louder), and a receiver or loudspeaker which changes the electrical signal back into sound and delivers the louder sound to the ear. A battery powers the electronic parts. How the electrical signal is amplified and modified differentiates conventional hearing aid circuitry from advanced technology circuitry, such as programmable and digital hearing aids. Hearing aid circuits can be analog or digital. Analog circuits can be adjustable or programmable.
An adjustable analog hearing aid is not manipulated by a computer. All the adjustments of the hearing aid, such as the frequency response, the gain, and the output, are preset at the factory or can be changed by the audiologist using potentiometers on the hearing aid. The audiologist can fine tune the hearing aid for the hearing loss by changing screw adjustments. There is an external volume wheel, which allows the user to increase or decrease the loudness of the sound.
Typically, adjustable analog hearing aids are less expensive than programmable hearing aids, but they are not as flexible as programmable hearing aids and the audiologist is limited in the ability to precisely fine tune the parameters.
Different styles of hearing aids are available. Style selection depends upon the degree and configuration of the hearing loss, the physical dimensions of the ear canal, hearing aid circuitry, and manual dexterity of the patient. A behind-the-ear (BTE) hearing aid fits behind the ear and is attached to an earmold, which is worn in the ear. A BTE hearing aid may be recommended when there is a severe or greater hearing loss or for a young child. An in-the-ear (ITE) hearing aid fits in the concha of the ear. This style is appropriate for a variety of hearing losses. An in-the-canal style is smaller than the ITE hearing aid and the hearing aid is visible in the entrance of the ear canal. A completely-in-the-canal (CIC) is the smallest hearing aid available, fitting deeply into the ear canal. The CIC hearing aid is removed from the ear with an extraction cord. The volume adjustment on the CIC hearing aid is automatic; there is no external volume wheel.