An overview of the completely-in-the-canal hearing aid

As the ability to miniaturize electronic circuitry and components has progressed, modern hearing aids have become smaller and smaller. This trend has resulted in the completely-in-the-canal (CIC) hearing aid, which is the smallest hearing aid available today. This paper will provide an overview of the background, technology, and acoustics of CIC hearing aids. Topics to be covered include the origins and evolution of the CIC, miniaturization of components, and allied advances in enabling technology. Emphasis will be placed on the acoustic advantages of placing the CIC hearing aid deep in the auditory canal, including the effects on gain and distortion, the resulting frequency response in the ear, the significance of localization, the use of natural pinna cues, and the reduction of the occlusion effect. These topics will also be related to normal binaural hearing. The results of objective and subjective testing in these areas will be included. The paper will conclude with examples of challenging patient fittings that are possible with CIC hearing aids.