Crosstalk cancellation for users of bilateral bone-conduction hearing aids

A bone-conduction hearing aid delivers sound to both cochleae by vibrating the skull. Consequently, bilateral fitting results in poor stereo separation. Here, we demonstrate improved stereo separation using crosstalk cancellation in unimpaired listeners using two bone vibrators and in two patients with bilateral bone-conduction hearing aids. The crosstalk filters were calibrated using a psychophysical sound-lateralisation method and the benefit of crosstalk cancellation was assessed using masked thresholds when noise was presented to one side and a tone to the other. Improvements in masked threshold of ∼10 dB were demonstrated bilaterally in unimpaired listeners using digital filters typical of a clinical device. Improvements were also demonstrated bilaterally in one patient, albeit with a strong asymmetry, and unilaterally in another. Without recalibration of the filters, the patients' improvements decreased gradually over successive experimental sessions. We conclude that crosstalk cancellation can be successfully implemented for bilaterally implanted users of bone-conduction hearing aids but may require periodic recalibration.