| 摘要 |
<p>The present invention is intended for providing a directivity suitable for enlarging a region for satisfactory stereophonic listening position. <??>A loudspeaker unit comprises a loudspeaker box, a first loudspeaker attached to a front panel of the loudspeaker box, and a second loudspeaker having the same diameter as that of the first loudspeaker and attached to an upper panel of the loudspeaker box. The first loudspeaker is driven in a positive polarity and the second loudspeaker is driven in a negative polarity. Driving voltages E1 and -E2 respectively for driving the first and the second loudspeaker are optional voltages meeting E2/E1 < 1. The sound pressure of sounds radiated by the second loudspeaker is lower than that of sounds radiated by the first loudspeaker. The directivity factor of the synthesis sound pressure of the first and the second loudspeaker at a sound receiving position with respect to the 90 DEG -direction is equal to the product of the directivity factor D(90 DEG ) of the loudspeaker and a value (1 - alpha ) smaller than one. Accordingly, the output sound pressure of the loudspeaker can be reduced regardless of frequency. <IMAGE></p> |
