How to Measure Hearing Aid Domes
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Hearing aid domes are used with receiver-in-ear (RIC) hearing aids, and they fit inside the ear to protect the amplifier, hold the tube in place and create a seal. They come in a huge range of sizes and types, and it’s essential that they fit correctly for maximum comfort. This also helps with hearing aid effectiveness, as poorly fitting domes can leak sound and end up underperforming. Choosing the right shape and size of hearing aid dome ensures your hearing aids work as intended and that you can stay comfortable all day long.
Choosing the Right Shape
There are three main shapes of dome:
- Open dome: This type of dome lets in some natural sound, resulting in better sound quality with increases in sharpness. However, it also reduces bass amplification, and hearing aids with open domes generally require a little more power, as some sound leaks out through the vents. This type of dome also prevents the occlusion effect, where the user’s voice sounds boomier, and is ideal for mild to moderate hearing loss. Feedback can be an issue for those with more moderate hearing loss.
- Closed dome: Also called a vented or tulip dome, a closed dome has less venting than an open dome, resulting in better amplification of lower frequency sounds. This reduces the sharpness in higher frequencies, however, but typically produces better results in those with moderate hearing loss.
- Power dome: For those with severe hearing loss, power domes are often the answer. These domes block up the hearing canal completely, allowing maximum amplification with minimal sound leakage. However, these increase bass and decrease sharpness significantly. Power domes also eliminate feedback.
Choosing the right shape of dome is vital for comfort and sound quality.
Choosing the Right Size
Typically, the audiologist fitting the hearing aids will select the correct size of dome to ensure it fits properly. The dome should be fractionally larger than the ear canal so that it forms a reasonably secure seal, but it shouldn’t exert additional pressure on the skin of the ear canal itself. A perfectly fitting dome makes a light rustling noise when being inserted or taken out, and there should be a little bit of resistance.
For open domes, there should be no additional pressure inside the ear. With closed domes or power domes, there may be some additional light pressure that can easily be resolved by swallowing.
Hearing aid domes that are too small do not exert resistance when taken in or out, and extremely small domes may not even make a sound. Domes that are too small are generally ineffective, and they do not secure the hearing aid inside the ear.
Hearing aid domes that are too large start to feel uncomfortable very quickly. Open domes may exert additional pressure inside the ear as the vents deform, and voices may sound deeper and less clear. Power domes, in particular, may get extremely uncomfortable, and the pressure exerted on the ear canal walls results in soreness or swelling.
In extreme size mismatches, the dome may come off in the ear, which can necessitate a trip to urgent care. Do not try to take detached domes out of the ear canal yourself, as this can push the dome further down the ear canal and risks damaging the eardrum.
Ultimately, the best-fitting hearing aid domes feel comfortable, feel secure and get the best out of your hearing aid. Different brands and dome types have slightly different sizing, so those who change brands or dome types may need to change their size.