How does FineHearing work and what are the benefits for MED-EL cochlear implant patients?
FineHearing, one of the three elements of Triformance in the MED-EL cochlear implant system, allows mimicking the processes of the normal hearing ear as closely as possible with advanced sound coding technology. Specifically, FineHearing uses tonotopic coding as well as variable-rate temporal coding in the apical region of the cochlea for a much more natural representation of bass tones.
In the normal hearing cochlea, not all regions in the cochlea work in the same way. In the middle and basal regions of the cochlea (i.e. in the regions encoding mid to high frequencies), the neural structures can only follow the slowly varying envelope of the sound signal. However, in the apical region (i.e. in the region encoding low frequencies), neural structures create action potentials in synchrony with the sound signal. This phenomenon is called "phase locking" and plays an essential role in encoding pitch information and musical tones.
FineHearing stimulates the cochlea in exactly the same way. While in the middle and basal region, constant high stimulation rates are used to allow the neural structures to faithfully represent the envelope of the sound signal, in the low frequencies, FineHearing matches stimulation rates with instantaneous sound frequency to produce phase-locked neural responses, thus better encoding pitch and musical tones, just like in normal hearing.
Research has shown that FineHearing coding strategies allow MED-EL CI users to more naturally hear low pitches, like the bass line in music, generally leading to a fuller and more natural listening experience. In essence, this provides reduced acclimatization time, potentially allowing MED-EL users to hear and understand sounds, speech and music better and quicker with their MED-EL cochlear implant than with other devices. And for bimodal recipients (CI in one ear and hearing aid in the other), FineHearing offers the best opportunity for natural-sounding pitch across ears because low pitches are naturally represented on both sides, using an electrode that reaches the apical region in the CI ear coupled with residual low frequency hearing in the HA ear.