遠心圧縮機BPF音の放射音計測

抄録

A measurement technique of radiated BPF sound from turbocharger compressor is treated in this paper. Since the environment of measurement in this study is not anechoic and the level of background noise is high, we could not find BPF peak level in the obtained sound spectrum measured by normal measurement microphone. A microphone with parabolic cone is used instead to reduce the effect of background noise. Using this technique, discrete peak of BPF is clearly observed in the result. To obtain absolute BPF level from the result, a level correction is needed due to the amplification effect of parabolic cone. We also conducted an experiment to measure amplification effect. The method in this study is also applicable to sound measurement those with high level of background noise.