Subjective Evaluation of a Focused Sound Source Reproducing at the positions of a Listener’s Moving Hand

Herein, we investigated the subjective impression of a mid-air sound source whose position was directly manipulated by hand tracking. The mid-air sound source was generated as a focused sound source based on wave field synthesis with a 32-channel linear loudspeaker array. The hand position was tracked using motion capture equipment (Leap Motion). If the focused sound source is not moved within the frame depending on the motion capture acquisition period, the focused sound source cannot be moved smoothly. To achieve smoother and more natural movement of the focused sound source, we moved the focused sound source sample-by-sample in the frame using an all-pass filter. Subjective tests indicated that sound localization and enjoyment increased when the focused sound source followed the hand movements of a listener. Moreover, when the focused sound source was pinched and moved, the sense of movement was enhanced by changing the sound volume according to the moving speed of the focused sound source. The proposed system can contribute to the development of innovative 3D audio applications.