FUNDAMENTAL CHARACTERISTICS OF STRUCTURE- BORNE SOUND RADIATED BY A VIBRATING PLATE

In order to suppress the structure-borne sound radiated by a vibrating plate, the vibration must be controlled. Unlike the conventional vibr ation control method which aims merely to eliminate the vibration, thi s paper rather uses the vibration itself to urge the cancellation mech anism of sound. First, with a view to elucidating the generation mecha nism of the structure-borne sound, an acoustic intensity distribution pattern is measured experimentally at each vibration mode of a plate. Then, from a viewpoint of negative acoustic intensity observed in the acoustic distribution patterns, the cancellation mechanism of the soun d is discussed, and the reduction of the acoustic power due to the neg ative intensity being investigated. In addition, it is pointed out tha t the radiation patterns proposed by Maidanik do not hold good for som e vibration modes. Finally, the relationship between the radiation eff iciency, the radiation power and the vibration level is clarified.