Procedure for verification of sound source coverage over fa莽ades according to the International Standard ISO 140-5
- 作者：José ; Luis Sá ; nchez Bote ; jbote@diac.upm.es ; Antonio Pedrero Gonzá ; lez ; Juan José ; Gó ; mez Alfageme
- 关键词：ISO 140&ndash ; 5 ; Sound insulation ; Faç ; ade ; Loudspeaker directivity ; Coverage requirements
- 刊名：Applied Acoustics
- 出版年：2012
- 期刊代码：12_0003682x
- 类别：et
- 出版时间：September, 2012
- 卷：73
- 期：9
- 页码：977-985
- 文件大小：1979 K
摘要
This paper presents a new verification procedure for sound source coverage according to ISO 140-5 requirements. The ISO 140-5 standard applies to the measurement of fa莽ade insulation and requires a sound source able to achieve a sufficiently uniform sound field in free field conditions on the fa莽ade under study. The proposed method involves the electroacoustic characterisation of the sound source in laboratory free field conditions (anechoic room) and the subsequent prediction by computer simulation of the sound free field radiated on a rectangular surface equal in size to the fa莽ade being measured. The loudspeaker is characterised in an anechoic room under laboratory controlled conditions, carefully measuring directivity, and then a computer model is designed to calculate the acoustic free field coverage for different loudspeaker positions and fa莽ade sizes. For each sound source position, the method provides the maximum direct acoustic level differences on a fa莽ade specimen and therefore determines whether the loudspeaker verifies the maximum allowed level difference of 5 dB (or 10 dB for fa莽ade dimensions greater than 5 m) required by the ISO standard. Additionally, the maximum horizontal dimension of the fa莽ade meeting the standard is calculated and provided for each sound source position, both with the 5 dB and 10 dB criteria. In the last section of the paper, the proposed procedure is compared with another method used by the authors in the past to achieve the same purpose: in situ outdoor measurements attempting to recreate free field conditions. From this comparison, it is concluded that the proposed method is able to reproduce the actual measurements with high accuracy, for example, the ground reflection effect, at least at low frequencies, which is difficult to avoid in the outdoor measurement method, and it is fully eliminated with the proposed method to achieve the free field requisite.