| 摘要 |
PURPOSE:To detect the information on a sound source side correctly and to improve the forecasting accuracy of the rate of sound attenuation by measuring the transmission functions of the cases when two pipelines A, B are connected to the same sample sound source and the acoustic impedances at the inlets of the pipelines. CONSTITUTION:The transmission function H0i between the sound pressure Pi at the inlet of the pipelines of the case when two mutually different pipelines A, B are connected respectively to the same sample sound source and the physical quantity P00 that is intrinsic to the sound source, has coherency with the sound pressure of the pipelines and does not change with pipeline conditions as well as the acoustic impedance Zi at the inlet of the pipelines are measured respectively and the impedance Z00 on the sound source side is determined by the calculation equation Z00=-(H0iA-H0iB)/(H0iA/ ZiA-H0iB/ZiB). Here, the suffixes A, B of the equation denote the cases when the pipelines A, B are connected respectively. The physical quantity P00 may be the input voltage to a speaker in the case of a speaker sound source. The transmission functions H0iA, H0iB can be measured with commercially marketed measuring devices, and the acoustic impedances ZiA, ZiB are determined by providing two microphones by leaving a distance S. |
