Tubing directs the amplified sound from a hearing aid to the external ear canal. It is the job of earmolds and domes to point the tubing down the canal toward the eardrum, and to hold the tubing in place.
Earmolds can be made of a variety of materials, including: acrylic, vinyl, silicone, and other materials. The audiologist determines the best type of material based on a number of factors (not discussed here). Silicone is most often used in earmolds for children because it is very soft (Figure 1). A soft earmold is desirable for children in case they fall or bump their ears. Additionally, silicone earmolds can be hypo-allergenic. Some earmolds will have a small tunnel running through them to provide airflow into the sealed ear canal. These tunnels are called vents (Figure 1).
Domes refer generally to a class of tips that are non-custom, meaning no earmold impression is taken. Instead, domes are mass-produced and come in a few standard sizes (Figure 2). They are typically flexible, and are most often used when a tight-fitting earmold is not necessary.