The variety of hearing aids that are available to consumers today allows almost any problem connected with hearing loss to be resolved. However even the use of the most state-of-the-art hearing aid cannot completely protect the patient from every discomfort associated with it, unless it is used together with otoplastics. The term otoplastics is used here to denote everything that is manufactured on the basis of an individual ear impression: an ITE aid case or an individual earmould used together with a BTE hearing aid.
An individual earmould has a number of advantages over a standard one. It fits the patient’s ear more precisely, which helps to avoid many problems normally associated with wearing an aid. It allows to fix the hearing aid on the ear more securely, to achieve maximal sound amplification. It also helps to avoid the feedback effect and skin irritation as it fits closer to the walls of the ear canal. In some cases an individual earmould can even significantly improve the quality of sound transmission due to special acoustic modifications.
As the patient may have to use the hearing aid for hours every day, the individual earmould should fit perfectly in the ear canal, exactly replicating the anatomical curves. The material the earmould is made of should be nice to touch, resistant to temperature, moisture, earwax. Compliance with the most contemporary world standards also implies biocompatibility of the material. Modern earmoulds vary greatly in size, form and material. Only a qualified specialist, taking into account the specific anatomical features of the patient’s ear canal, the character of the hearing loss and the type of the hearing aid, can determine what form the earmould should have and what material it should be made of.
As far as the material is concerned, four types of earmoulds are distinguished: hard, soft, pharioflex and combined earmoulds. Hard earmoulds are made of acryl – a material characterized by flexibility and fine acoustic properties. At the same time acrylic earmoulds may often cause discomfort, rubbing the sensitive ear skin.
Soft earmoulds are produced of PVC and similar elastic materials. Recently they have been used less often, as their acoustic properties are not as good as those of other types of earmoulds.
The earmoulds made of pharioflex are characterized by an optimal combination of properties. Due to the material’s ability to change its qualities depending on the temperature, earmoulds of this type get more flexible when they are fitted into the ear canal and thus don’t cause any discomfort.
Combined earmoulds are made with two materials – a hard one and a soft one (mostly acryl and pharioflex). The production technology of such earmoulds is rather complicated, that’s why they are used very seldom.
A well-chosen high-quality earmould is essential for the use of a BTE hearing aid to be comfortable and efficient. That is why production of earmoulds plays an important role in hearing loss correction. Almost every modern hearing loss correction center has a laboratory of its own. Qualified specialists working in such laboratories will make individually for every patient an earmould of the suitable type and form, ideally fitting the anatomic shape of the ear.
The first stage of earmould production is making an ear impression. Before making an ear impression the specialist examines the ear with an instrument called otoscope to exclude inflammatory diseases and presence of foreign bodies. Any inflammation of the middle ear is a contraindication to making an impression. That is why the patient must inform the doctor about any kind of pain or discharge from the ear. After the examination the doctor fits a tampon inside the ear canal to protect the eardrum and fills the ear canal with putty. When the impression sets, it is removed from the ear canal. The ready impression exactly replicating the curves of the ear canal serves as the basis for making a “negative” mould, which is then used to make the actual earmould. At the final stage of production the earmould is finished off: it is polished and, if necessary, holes are drilled in it for ventilation or improving the sound quality.
During the process of making an impression it’s necessary to follow the doctor’s recommendations. In that case the ear impression will be as accurate as possible and the earmould made on its basis will ideally fit in the ear canal.
Having just begun using an individual earmould a patient can feel unaccustomed, the transmitted sound may seem unnaturally loud or quiet. Sometimes that means that the hearing aid needs adjustment. But if the patient feels uncomfortable using the earmould – if it makes the ear sore, produces whistling sounds, fits uncomfortably in the ear or falls out – then the producing laboratory must remake it.
If the individual earmould is correctly chosen and produced it can be used for several years (children under the age of 12 are recommended to change the earmould at least every year because of their continuing growth). To extend maximally the lifetime of the earmould you should give it regular care. The tube connecting it to the case of the hearing aid should be regularly cleaned of dirt, moisture, earwax. To do that you should disconnect the earmould together with the tube from the hearing aid, rinse it in warm water, dry it carefully and connect to the hearing aid again. The tube should be replaced at least twice a year, as it gets rigid with time and cannot be cleaned out. Various means can be used for the cleaning of earmoulds: special tissues, cleaning sprays etc. A wide choice of such goods can be found in most shops specializing in selling hearing aids.