2.2 Setting
The experiment was conducted in a sound-attenuated audiometric booth where three loudspeakers were positioned 1 m from the centre of the subject’s head, at angles of -90° azimuth (left), 0° azimuth (front), and +90° azimuth (right) on the horizontal plane. All patients were fitted with a BCD (ADHEAR, MED-EL, Innsbruck, Austria) that was uniformly programmed with omnidirectional microphone settings. ADHEAR can be worn with an adhesive adapter or headband. For SSD, sufficient transmission of bone conduction (BC) sound should be ensured to stimulate the contralateral cochlea; the headband was chosen in this study [9,10]. The volume setting of the BCD was set to the patient’s preference, with the optimal level not changing during all experiments.