Tonotopicity and CCC
To appreciate the importance of Complete Cochlear Coverage, it is helpful to understand the role of the cochlea in the normal hearing process. The cochlea is a small (pea-sized), spiral-shaped structure located in the inner ear. It is responsible for converting sounds from mechanical vibrations into signals that are passed on to the brain via the auditory nerve. This process is performed by specialised sensory cells (hair cells) within the cochlea. These hair cells are arranged accoriding to pitches or tones. This arrangement is referred to as tonotopicity. In normal hearing, low-frequency pitches cause nerve fibres to fire in the apex, or top region of the cochlea. High pitches cause nerve fibres in the base of the cochlea to fire.
Above, a graphic illustration of the tonotopicity of the cochlea.
What is Complete Cochlear Coverage (CCC)?
Complete Cochlear Coverage is achieved by having a long electrode array that is present from the most apical to the most basal region. This range of stimulation is crucial because it provides the implant user with a complete representation of sound. A short electrode array is only able to stimulate a restricted region of the cochlea, leaving nerve fibres in the apex untapped.
Complete cochlear stimulation provides the implant user with a richer, more natural sound quality1
. For individuals implanted with long electrode array, this translates into a number of potential advantages. Studies show, for example, that Complete Cochlear Coverage improves speech discrimination in a vast majority of implant users.2
MED‑EL’s unique, soft, and flexible electrode arrays are the same length as the cochlea, which takes advantage of all available nerve fibres.
Benefits of CCC are:
- superior sound quality
- a maximisation of the cochlea’s natural potential
- improved speech discrimination2
- best representation of FineHearing™ technology