One very important component of a hearing aid is the earmold. This plastic insert must be carefully fitted to the end-user so that amplified sound will be properly conducted into the ear. In the case of canal and in-the-ear aids, all the components are integrated into the earmold itself. With behind-the-ear models, the earmold is separate from the rest of the aid. Earmolds may be made of hard or pliant plastics that fill the ear without causing discomfort or a "plugged" feeling. A loose fit, on the other hand, can contribute to feedback. The dispenser can modify the earmold with a tiny hole to equalize pressure on either of its sides. A large vent can also be created that will improve the aid's response. In all, the selection and fitting of an earmold is quite important to the aid's effectiveness.

P.S. Older hearing-aid users should have their earmolds refitted to compensate for changes in ear shape.