Binaural audio frontend processing for cochlear implants inspired by the medial olivocochlear reflex

Objectives The “MOC strategy” is a binaural audio processing method for cochlear implants (CI) inspired by the medial olivocochlear (MOC) reflex. Although the strategy can improve hearing for CI users, it requires a bilateral channel pairing for the contralateral control of the backend compression and, therefore, the same number of frequency channels and electrodes on both sides. This may limit its clinical applicability. As a step to overcome this difficulty, here, we present and test a version of the MOC strategy designed to operate at the front end (FE) rather than the back end of processing, referred to as the MOC FE . Design The MOC FE strategy was implemented and tested in combination with a pair of functionally independent bilateral MED-EL FS4 audio processors. The hearing of bilateral CI users was compared for the MOC FE as well as for two reference strategies: the standard FS4 strategy and a backend MOC strategy. The MOC FE and MOC strategies were implemented with fast contralateral inhibition. Measures included (1) speech reception thresholds for sentences in fluctuating and stationary noise, in unilateral and bilateral listening modes, and for three different speech levels; and (2) sound source localization in quiet and in noise. Five bilateral users of MED-EL CIs participated in the evaluations. Results (1) For speech intelligibility in fluctuating noise, the MOC FE was as beneficial (re FS4) as the backend MOC strategy, except for one specific spatial configuration (S −60 N 60 ), where the MOC FE produced no benefits while the MOC strategy did. (2) Neither the MOC FE nor the MOC strategies improved intelligibility in a stationary noise, possibly because they involved fast rather than slow contralateral inhibition. (3) The binaural MOC FE and MOC strategies tended to improve sound source localization slightly relative to the FS4 strategy. Conclusion The MOC FE can become a successful alternative to the MOC strategy, as it may be more easily implemented in clinical devices and applied to a broader range of clinical map configurations.