Reduction of low-frequency resonance utilizing active noise control system in enclosed three-dimensional space

摘要

In an enclosed space, such as a residential space, if the frequency of a noise and the naturalfrequency of the space are close in value, the noise is amplified by a phenomenon calledresonance. Typical dimensions of residential spaces are generally close in value to thewavelength of a low-frequency sound of about 100 Hz or less. Measures against lowfrequencyresonance should therefore be taken. A simple active noise control system usingonly one secondary source was examined in this study. Its effect on reducing low-frequencyresonance was evaluated by experiment and acoustic analysis utilizing the boundaryelement method. From this study, it was confirmed that an active noise control system is aneffective way to reduce low-frequency noise in an enclosed three-dimensional space.However, the effect depends on appropriate placement of the secondary source and errormicrophone. It was also confirmed that computational acoustic analysis can accuratelypredict the effect of active noise control. Resonated noise can therefore be effectivelydecreased by optimizing the placement of an active noise control system through the use ofacoustic analysis.