Author (s)
Genta Yamauchi, Yosuke Tanabe
Affiliation
Research and Development Group, Hitachi, Japan
Publication date
2023
Abstract
People perceive sound as affected by diffraction caused by complex shapes such as the head and auricle and evaluate the sound field in which they are staying. This diffraction effect varies depending on the arrival direction of the sound. The loudness of sound also differs depending on the arrival direction of the sound. On the other hand, a sound field such as a railroad cabin is generally evaluated by the Aweighted equivalent continuous sound pressure level measured with an omnidirectional microphone at several points. This example shows that products are often used in spaces where people stay, so the positional relationship between the product (the sound source) and people is also important. Therefore, the arrival direction of sound radiated from a product needs to be known to proceed with the acoustic design efficiently. The conventional technologies for solving these problems have three issues. First, microphone arrays with microphones placed on a plane surface are used for sound-source localization to locate sound sources. However, the number of microphones in the array or the array size generally needs to be increased to perform highly accurate sound-source localization. Therefore, highly accurate sound-source localization and high portability are the relationships of trade-offs. Second, when subjectively evaluating the sound environment in which a product is used, the sound environment needs to be reproduced with high reality. This reproduction requires three-dimensional sound field recording. In recording sound using the microphone array described above, each microphone in the array generally records sounds. However, the sound recorded by each microphone lacks information on the arrival direction of the sound. Therefore, the recorded sound cannot be said to be appropriate for subjectively evaluating the sound environment. Finally, omnidirectional sound-source localization may be necessary for some products. However, the microphone array configuration limits the directions in which one can analyze the sound-source localization. From the above, we believe that we can obtain guidelines for acoustic design necessary to improve the quietness of products. We aim to construct a system with the following three functions to obtain these guidelines. (a) High portability, (b) Three-dimensional sound field recording, (c) Omnidirectional sound-source localization. In the following, we explain the details of our study to construct a system with the above three functions.
Full paper
https://www.jstage.jst.go.jp/article/ast/44/2/44_E2275/_pdf/-char/ja
Keywords
sound-source localization, spherical harmonics, high portability, three-dimensional sound field recording