All custom made hearing aids, ear molds and some hearing protectors are made from a “cast” of the ear. The cast is referred to as an ear impression. The hearing specialist makes the ear impression in the office. It takes about 10 to 15 minutes. A special cotton or foam dam is placed in the ear canal to protect the eardrum, and then a silicone material is placed in the ear canal using a syringe. When the material hardens (about 5 to 10 minutes later) the cast, along with the dam are removed from the ear canal. Often, the ear canal will be “oily” after the impression is removed. This is normal. The oil comes from the material and prevents the material from sticking to the skin.
Tell the hearing specialist before the ear impression is obtained if you are allergic to plastic, dyes or have any ongoing problems such as chronic perforation on the ear drum. It is dangerous to attempt this procedure yourself. It takes a trained specialist to visualize a normal eardrum and then appropriately place the block.
You can watch the ear impression procedure at: