振動放射音の近接遮へいに関する研究

抄録

A close-fitting acoustical enclosure effectively reduces machine noise especially at high fre-quencies. At low frequencies, however, the reduction performance is degraded because of acoustical resonances of the air space inside the enclosure and of mechanical connections between the machine and the enclosure plate. To solve this problem, a new concept of active control system is developed. Using a piezoceramic actuator, the control forces are inputted directly to the enclosure plate to minimize the vibration of the plate. The control action improves the insertion loss of the enclosure plate particularly at some low modal frequencies of enclosure plate. Using this new control scheme, the enclosure plate can reduce radiated noise by more than 10 dB at almost all frequencies.