The housing of this hearing aid completely fills the concha. The advantages include a longer battery life, the availability of a power version for severe hearing loss, and improved operation.
This is a small and discreet custom model. The hearing aid housing sits in the ear canal, thus only filling half of the concha.
The smallest custom model, the CIC offers the ultimate in discretion as it is virtually invisible from the outside. These devices typically have a nylon strand to facilitate removal from the ear.
This subgroup of CIC devices are hearing aids that are worn deep in the ear canal making them completely discreet. Phonak's Lyric is an example of an IIC hearing aid.