Earmolds and hearing aids that fit in the ear are molded to fit into your ear canal, with the sound coming out of a hole in the molded material. That hole is called the "bore", and it leads to the speaker of the hearing aid.

Since the sound from the hearing aid's speaker must travel down that bore into your ear canal and then to your eardrum, there are a couple of things that are important to consider. The bore should be:

• cleanly drilled so that the sound is not impeded in its travel.
• kept clean of earwax and moisture.
• aimed at the eardrum.
• shaped for your particular loss.

The shape of the bore can matter, because typically, the hole is drilled into the mold so it has a constant diameter, and for most hearing losses, that's sufficient, but the bore may be specially shaped (like a horn) with a graduated diameter to enhance the travel characteristics of high frequency sounds.

The bore may be just a hole, but it can be an important factor in hearing better.