Different Types of Hearing Aids and Their Functions

Different Types of Hearing Aids and Their Functions

Decreased of hearing function can occur at any age, which is characterized by a reduced ability to receive or identify external sound stimuli. Prelingual hearing loss occurs before a child develops speech and language, while postlingual hearing loss appears after a child has acquired language. Hearing loss affects the ability to communicate with others, but the use of hearing aids can provide the hearing function that should be owned.

A hearing aid is an electronic device that is used to amplify sound that enters the ear. Hearing aids consist of several components, such as: microphone, amplifier, receiver and ear mold. The external sound signal is received by the microphone, conversed into electrical energy and forwarded to the amplifier. Amplifier will amplify the sound and send the electrical signal to the receiver. The electrical energy received by the receiver is converted back into sound energy and transmitted to the ear canal. The amplified sound then be delivered to the ear canal through a channel that fuses with the ear mold. Ear molds are made of acrylic or silicon material and adjusted to ear canal, so they are individual. Too small ear moulds can cause acoustic leakage resulting in a ringing sound, and too large ear molds caused injury to the ear canal.

Based on the working system, hearing aids are divided into analog and digital system. Hearing aid with digital systems can be adjusted according to the needs of the wearer, more clearer and identical to original sound. While in hearing aid with analog systems, the circuit settings have been determined by the manufacturer, so they cannot adapt to the needs of the wearer. The received sound is also prone to distortion and uncomfortable to use in a noisy background.

Different types of hearing aids are offered with various benefits. The hearing aid selection must be adjusted to the degree of hearing loss through audiometry examinations in adults or ABR/ASSR examinations in children. There are several types of hearing aids according to the placement of hearing aids, such as: behind the ear hearing aids, in the ear hearing aids, in the canal hearing aids, completely in the canal hearing aids, and pocket hearing aids. Pocket hearing aids are the largest one and usually used in patients with severe or profound hearing loss. The completely in the canal hearing aid is the smallest type of hearing aid and assembled near to the eardrum, so it is not visible from the outside. However, this type of hearing aid has a limited ability to amplify sound and only beneficial in mild to moderate degree of hearing loss. Hearing aids use batteries as an energy source, so it is necessary to replace the batteries regularly to get the most advantage of the hearing aids.