Abstract
This paper describes a noise reduction design of random impacted structure like a coin storage box of a coin counting machine. The sound power radiated from the box is estimated based on probabilistic model of random impact forces. The integrated sound power in frequency domain is used as an index for an evaluation of sound reduction. In this structural modification, straight dimples are added to the box so as the dimples cross antinodes of the distinguished mode of sound power. As a result of sound power measurement, it is confirmed that the proposed method is applicable to noise reduction design.
