The Completely in the Canal (CIC) hearing aid followed the development of the In the Canal (ITC) hearing aid. Again it was accomplished by decreasing the size of all the hearing aid components along with a smaller battery. Depending on the size of the ear canal, when it is placed in the ear, it is either barely visible or not visible at all which is a desirable feature to some people. The disadvantage is that it is more expensive. In addition to the cosmetic advantage of CIC hearing aids there are also some acoustical advantages. First, due to the microphone being further down the ear canal, CIC users are not bothered by wind noise as much as users of other styles of hearing aids. Also, because of the microphone placement, many users are able to use the telephone without the hearing aid whistling (feedback). It is also reported that the microphone location also helps with depth perception of sound which makes it easier to hear in a noisy environment.

Like the ITC, the entire hearing aid is built into a custom-made shell obtained from an impression of the ear canal. The difference between the CIC and the ITC is that the CIC is recessed a few millimeters into the ear canal and extendes deeper toward the eardrum. This aid is the least visible. This style of hearing aid is most appropriate for mild to moderate, and sloping high frequency hearing losses.