抄録
It is believed that a helmholtz resonator is a good device for reducing the noise level of a discrete frequency noise, and that the frequency of the resonator can be estimated by a simple theoretical formula. Actually, however, we cannot deny the possibility of an unexpected increase in the noise level due to the resonance between a traveling tone and the resonator. Also, there are few papers which treat of the actual design method of a resonator, especially the dimension of a resonator in relation to the size of a main duct conveying a tone to be reduced. In the present experiment, the theoretically estimated frequency is examined ad to whether its noise level is reduced at that frequency by the resonator or not. The experimental data which are useful for designing a resonator with an optimum geometry are also presented.
