声强的有旋性与表面声强

本文应用复声强的概念,讨论了复声强的实部即有功声强的有旋性质。指出:在声场中真正传递声能量者仅是有功声强中的无旋分量。所以在应用双传声器声强测量法测量声功率时将受到有旋性的影响。有功声强的无旋分量与表面声强有关,因此测量表面声强可避免有旋性的影响。本文从自功率谱的角度给出了表面声强的有关计算公式,为表面声强测量提供了理论基础。

Rotational character of sound intensity and surface sound intensity

Using the concept of complex sound intensity, we discuss in this paper the rotational character of the active intensity which is the real part of the complex sound intensity. It is shown that it is the irrotational component of the active intensity that transfers sound energy in sound field. The measurement of sound power by use o the two-microphone technique will be affected by the rotation of the active intensity. Because the irrotational component of the active intensity depends on the surface sound intensity, measuring the surface sound intensity can avoid the effect of the rotation. Formulas about the surface sound intensity which are based on the auto-power spectra and provide a theoretical basis for measuring the sueface sound intensity are given in this paper.