Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : July 18, 2024
The rainfall noise hitting umbrellas obstructs ambient sound, making it difficult for the visually impaired to go outside during rainfall. To solve this problem, umbrellas with low rainfall noise have been developed, but no quantitative evaluation method for rainfall noise of umbrellas has been established. Last year, we fabricated a tank for rainfall with reference to ISO 10140-5:2021 and reported the results of rainfall sound evaluation of umbrellas in artificial rainfall, but we could not reproduce the acoustic characteristics of natural rainfall. In addition, acoustic laboratories are vulnerable to water, and the amount of water used during measurements should be as small as possible. Therefore, this paper proposes a new evaluation method using drips at a single point. This method analyzes the sound of drips at several points selected in consideration of the shape of the umbrella, and then sums up the results in terms of energy. The effectiveness of this method was examined by measuring the rainfall sound of umbrellas using the drip evaluation method and comparing the results with those of natural rainfall and using a rainfall tank. The results of the study showed that quantitative evaluation is possible with artificial rainfall using a minimum amount of water as a relative comparison for each measurement target. In the future, we plan to investigate whether the spectral balance of natural rainfall can be reproduced by improving the drip position.
