Hearing aid ear molds
Hearing aids are generally thought of as consisting of a microphone, an amplifier circuit, and a receiver. In fact, hearing aids also have an important component-earmolds. An ear mold is a device that transmits output sound from the earpiece of a hearing aid to the external auditory canal or eardrum.
The acoustic plug-in is part of a complete hearing aid system.
Why use ear molds
Before the emergence of ear molds, hearing aids were connected to the ear canal with different size ear plugs, and different size ear canals used different size ear plugs. However, because the earplugs and the ear canal are not tightly matched, when the volume of the hearing aid is large, the output sound of the hearing aid will leak to the microphone through the external ear canal, and acoustic feedback will occur. In this way, hearing aids cannot meet the needs of patients with severe and very severe deafness.
In addition, the earplugs are easy to fall off, which is not good for hearing aid fixation, especially for behind-the-ear hearing aids. Based on this, ear molds are produced, which are also two functions of ear molds.
Ear mold concept
Ear molds are acoustic inserts made according to the shape of the ear cavity and external auditory canal of the hearing aid user. It is placed in the ear cavity or ear canal, and is fixed in the ear using anatomical structures such as the ear wheel and the opposite ear wheel, the tragus and the opposite tragus, and the external ear canal.
The ear mold is an acoustic plug-in, which is part of the hearing aid system. It transmits the amplified sound of the hearing aid from the receiver of the hearing aid to the external ear canal or tympanic membrane. For in-ear, ear canal, and other customized hearing aids, the shell of the hearing aid is equivalent to an ear mold.
Standard ear mold as shown. This ear mold is a plug-type ear mold with a sound hole diameter of 2mm and no vent holes. Due to its better sealing in the ear, it is suitable for severe and very severe deafness. There is a small metal ring or a small ring of thermoplastic rubber on the outer end of the ear mold sound hole. The earphone of the box-type hearing aid is buckled on this ring, and the sound can be transmitted to the external ear canal through the sound hole. Therefore, standard ear molds are suitable for high-powered cassette hearing aids.
Standard ear mold composition
A-ear wheel B-ear screen
C-cut between the tragusD- pair of tragus
E-outer ear F-ear wheel
Figure 4-2 Anatomy of the auricle
Figure 4-3 Ear mold position
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