The Origin of the CIC Hearing Aid – Part III
This post continues the paper trail story of the origin of the CIC (completely-in-canal) hearing instrument. Two previous posts traced the story from its beginning with deep canal fittings, then to the XP Peritympanic, and now to the CIC itself. These were three separate and distinct stages, with each resulting from special goals. With deep canal fittings, the goal was for the elimination of the occlusion effect. The Peritympanic goal was for invisibility and acoustic advantages. The CIC, as reported in this post, was based primarily on a cosmetics goal.
Moving Beyond the XP Peritympanic
In an attempt to avoid some of the detailed procedures required for the XP, specifically of making an ear impression that included the tympanic membrane and requiring a training program, manufacturers suggested shorter impressions (primarily to be just beyond the second bend of the ear canal), reducing the length of the finished product to not go as deeply as a deep fitting hearing aid, and tapering the end of the hearing aid to facilitate insertion and wearing comfort. In fact, most manufacturers shortened the finished product as much as they could from the impression to provide for improved comfort and ease of insertion. But, the real goal was to make them small enough to have all components fitted within the ear canal, often 1-2 mm inside the aperture of the ear canal. And, because the components were placed within the ear canal, they started calling this style of hearing aid the CIC (completely-in-the-canal) to differentiate it from its closest rivals, the ITC (in-the-canal) and the peritympanic hearing aids.
The modifications to the product, identified in the literature as the CIC, were popularized between 1993 and 1994 by Starkey and Argosy hearing aid manufacturers, and essentially every other U.S. hearing aid manufacturer followed suit by 1994 (Figure 1), including Philips (1993), who introduced the M10 in 1993, a CIC hearing aid that provided “the best alternative to peritympanic deep-canal fitting.” By 1993, the term CIC (completely-in-canal) was an accepted term based on the definition that the shell and all components (internally or externally) must be seated 1 mm or deeper inside the entrance of the ear canal (Giller, 1993).
CIC vs. Deep Canal vs. Peritympanic
This differentiation was explained in 1994 in an interview conducted by The Hearing Review seeking to fully understand the technology surrounding CICs, ITC, and Peritympanic hearing aids (Staab, 1994). A major distinction was that CICs and Peritympanic instruments were completely different and should not be treated otherwise.
As reported by Staab (1994), a “Peritympanic” instrument had three unique features: 1) the medial end of the instrument penetrates the bony portion of the external auditory canal sufficiently for the residual cavity to be approximately 200 mm2; 2) the medial end of the instrument must provide a full seal in the bony part of the auditory canal; and 3) the microphone position must be flush with the aperture of the external auditory canal, or slightly inside the aperture (Figure 2).
In contrast, the typical CIC instrument is shorter in length and is placed 1 to 2 mm inside the entrance of the ear canal. The shell and all components (internally or externally) must be seated inside the entrance of the ear canal. There is no specification as to where or how the CIC should terminate. Its primary style is to be completely within the ear canal for cosmetics purposes and to fulfill its description as being completely-in-the-canal. The CIC is compared with the ITC and Peritympanic hearing aid in Figure 3.
Deep Canal is Not a Hearing Aid Style
A further distinction is made in that a “deep canal” instrument is not a style, but relates to where the instrument terminates within the ear canal. On the other hand, a CIC is a style of hearing aid – one designed to be virtually unnoticeable in the ear canal (Gudmundsen, 1994).
A deep canal instrument is generally accepted as terminating past the second bend of the ear canal. There is no faceplate location requirement. Essentially, any hearing aid style could be deeply fit if it extended to that depth or beyond. “Deep canal fit” is a description, not a style. It describes any hearing aid, including those styles that have the shell or any of the components outside the ear canal, but fit into or beyond the second bend. Any BTE, ITE, ITC, CIC, Peritympanic, or RIC (receiver-in-canal) hearing aid style could be made to fit deeply, depending on where and how the instrument terminated, regardless of its faceplate or microphone positioning.
Giller, R. Completely in the canal: a new style for a new clientele, Hearing Instruments, Vol. 44, No. 4, pp 24-25, 1993
Gudmundsen, G. Fitting CIC hearing aids – some practical pointers, The Hearing Journal, Vol. 47, No. 7, pp 10, 45-47, July, 1994.
Philips Hearing Instruments. M10. The best alternative to peritympanic deep-canal fitting, Philips Hearing Instruments Brochure 3122 156 12011, 1993.
Staab, W.J. Interview. Clarifying the CIC Mystique, a perspective on ITCs, CICs and Peritympanic instruments, The Hearing Review, August, 1994, pp 19-20.