The acoustic device 10K illustrated in FIG. 12 reproduces the left ear signal with bidirectional directivity by using the speakers 11LA and 11LB arranged back-to-back. Therefore, with regard to the left ear signal, the level of sound that propagates toward a right ear direction of a listener MA sitting on the A-side seat (indicated by an arrow b) becomes lower than the level of sound that propagates toward a left ear direction of the listener MA (indicated by an arrow a), and this makes it possible to reduce a crosstalk component related to the left ear signal. In addition, the left ear signal is a reversed-phase signal, but this signal is also heard by a listener MB sitting on the B-side seat. In this case, the level of sound that propagates toward a right ear direction of the listener MB sitting on the B-side seat (indicated by an arrow d) becomes lower than the level of sound that propagates toward a left ear direction of the listener MB (indicated by an arrow c), and this makes it possible to reduce a crosstalk component related to the left ear signal.
