The role and development history of ear molds in hearing aids

Earmold (earmold) is an acoustic plug-in, as a part of a complete hearing aid system, it transmits the amplified sound of the hearing aid from the receiver of the hearing aid to the external auditory canal or tympanic membrane.For custom hearing aids such as in-ear ear canal type, the shell of the hearing aid can be regarded as an ear mold.With the development of the history of hearing aids, the shape, material, and manufacturing process of ear molds have undergone great changes. People’s understanding of the acoustic properties of ear molds has gradually deepened. Ear molds are not only a sound transmission component, but also to a certain extent. Improve the sound quality after hearing aids.

(XNUMX) The role of ear molds

Correcting the shape of the ear mold and the size of its various apertures can make up for the lack of acoustic characteristics of the hearing aid to a certain extent, further improve the sound quality after listening, and can meet the needs of patients in terms of beauty and comfort.This is the second function of the ear mold.

The third function of the ear mold is to make various hearing aids stronger.In particular, users of ear-level (behind-the-ear, in-ear, ear canal…) hearing aids are always worried that the hearing aids will be accidentally dropped and damaged.Since the ear mold is made completely in accordance with the shape of the auricle and ear canal, the physiological structures of the helix, the concha cavity, and the curvature of the external auditory canal will ensure that the ear mold and hearing aid are worn firmly. Hearing aid , The ear mold can also ensure the firmness of the hearing aid receiver.

(XNUMX) The history of ear molds

Our usual ear molds appeared in the 20s, and Western Electric Laboratories applied for a patent for ear molds.At that time, the ear molds were not custom-made, but a series of pre-made ear molds of varying sizes.A dentist in New York took inspiration from dental molds and began customizing ear molds according to the shape of each patient’s auricle.Since there was no back-of-the-ear Hearing aid , The shape of the ear molds is the so-called “standard type” suitable for box-type hearing aids.

Behind-the-ear hearing aids appeared in the 50s, shell-type and skeleton-type ear molds appeared one after another, but the ear canal type did not appear again.At the same time, the materials for ear impressions have also improved.In the past, plaster of paris was mainly filled into the external auditory canal and auricle, and an impression was obtained from the auricle after it was dry. In the early 50s, a soft material replaced plaster.

In order to standardize the shape, material, size, etc. of earmolds, the United States established the National Association of Earmold Laboratories (NAEL) in 1962. In the 70s, NAEL stipulated the standard size of the acoustic tube. Some have been named uniformly, and measures have been taken to promote the development of new ear molds and new ear print materials.

The most basic function of the ear mold is to establish a closed acoustic channel between the receiving end of the hearing aid and the tympanic membrane. The sound outside the ear mold is appropriately isolated, and the amplified sound in the ear mold will not leak out from the external auditory canal, causing sound. Feedback.

Link:      The role and development history of ear molds in hearing aids

REF: Hearing amplifierITE hearing aidsDigital Hearing Aids
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