How Is An Ear Mould for A Hearing Aid Made?

Depending on the hearing aid you need, you may require an ear mould to be made. An ear mould is not a generic item, it needs to be fully and correctly fitted to match the contours and shape of your ear. It is even stated that if you were to scan the outside of your ear it would be similar to scanning your fingerprint. We look at the steps needed to getting you that ear mould.

Ear impression is taken

To make an ear mould, requires taking a cast or impression of your ear. Prior to this your audiologist or hearing aid specialist will check your ear throughly first for ear wax, debris or infection. If your ear is clear with your permission they can continue on with the ear impression procedure. This will require placing what is called an 'oto-stop' into the ear canal at the point of the second bend in your ear canal. Two thirds of your ear canal is very sensitive, so it can feel like the otostop goes in further than it does. This is a small sponge with a job of sealing your ear canal closed so no impression material can go any further past the point you place the sponge. The oto-stop also has a thread that is firmly attached to the sponge that is pulled out once the impression has been made.

The impression is then made using a hand syringe or hand gun. A hand syringe requires you to mix together a silicone based material and hardner well before filling it into the syringe. A hand gun will be a sealed capsule of two component that will be mixed together as the lever of the gun is pushed, the gun is less wasteful however takes a lot more effort to use. The ear is then filled with the impression material, taking care to fill all needed areas of the outside ear. Once filled it should only take a few minutes to become hard and when it has it can be gently removed from the ear.

It will then be checked for any dents, air holes, parts missing or anything irregular in comparison to the ear, if it all looks good it is ready to go to the ear mould manufactuering laboratory.

Sending the impression to the ear mould making lab

Traditionally this is done via posting the impression in a small box labelled with the audiology department or hearing centre's return address. There are now more advanced alternatives such as a 3shape scanner which scans the ear impression as a 3D print which then is processed into CAD software and stored by the lab as a file, this method of scanning is more cost effective, gentler on the environment and also provides the option to save the ear impression temporarily on the computer system to be remade if it gets lost in any way.

Mould Making Procedure

At the lab if the ear mould has been physically sent in the post a negative is made of your ear impression to provide a cast to be refilled with the desired material of the ear mould.

If the ear impression was 3D scanned in, any extra faults or air holes that were found in the ear impression at that point can be filled in by the CAD software. The ear mould will then by 3D printed with near accurate results, if needed a further mould could be printed from the same impression within a 6 month period. 

Ear Mould Material Choice

What type of ear mould you end up with depends on a number of factors, your hearing level, ear shape and the hearing aid it is designed to fit with. Ear moulds can either be soft or hard. A soft mould will be made using silicone that provides with more flexibility and can be more robust if dropped making it a better choice for children, a soft mould also provides a greater seal and so is more often used for severe to profound hearing losses. It is also a wonderful solution for allergies.

A hard mould will be made out of an acrylic plastic, this tends to be the "standard" go to ear mould type for mild to moderate hearing loss adult hearing aid users unless their are allergies or irritations noted. Its rigid structure can be very comfortable but does allow sealing your ear to be come difficult overtime as your ear changes shape. Some acrylic moulds can be made with a soft acrylic meatus to reduce the risk of feedback or whistling.

Ear Mould Extra Modifications

Ear moulds are generally made clear and overtime can discolour. Some choose bright colours, especially great for children. A small image can also be added into the mix to be shown inside the ear mould to promote its use as a fun and positive accessory. Ear moulds can be coated with a UV or a nano coated protection particarly helpful for those with sensitive skin. Additionally at this point a small vent can be added which is a small hole that goes through the depth of the mould from the outside of the ear to the inside.

Final product

The hearing centre or audiology department will receive in the post an well thought out designed and proccessed ear mould with all the specfications asked for to suit the new hearing aid user of this ear mould.