Completely-in-the-canal (CIC) hearing aids are also custom designed. They fit the deepest into the ear canal, so they are the least visible and most cosmetically appealing. They sit very close to the eardrum, which improves sound quality and reduces "echo" sensations. They may also reduce the problem of wind noise and feedback on the telephone.
The battery life for this style is rather short because the battery is so small. The aid's size can also make it difficult to manipulate, particularly for people who have trouble with finger and hand dexterity (such as from arthritis).
Fitting completely-in-the-canal hearing aids generally requires additional appointments and remolding the casing to get the right fit. Some people may not be candidates for completely-in-the-canal hearing aids because of the shape of their ear canal or the severity of their hearing loss.