PARAMETRIC SPEAKER

摘要

PURPOSE:To obtain a parametric speaker safely and sharply in an orientation by attenuating a first wave effectively and using an acoustic filter giving scarce influence to a sound pressure level or the orientation of a second wave. CONSTITUTION:A sound source 21 is constituted by an ultrasonic wave transducer in the shape of array. An acoustic filter 22 is made of soft polyurethance foam having 120mm in thickness. The distance between the sound source 21 and the filter 22 is set 5o 1.5m and a microphone 23 is set at a position 1m separated from the filter 22. According to this construction, a first wave is lowered to a level safe for a human body and by using the filter 21 giving scarcely influence to the sound pressure level or the orientation of the second wave, the influence to the human body due to the ultrasonic wave can be eliminated without breaking a sharp orientation inherent to the parametric speaker and the parametric speaker can be practised.