朗德科技 声学测试培训课件.ppt

噪声 测量 第一部分: 声学基础;;Equilibrium state of fluid articles 平衡状态;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;Lp1; Assumption for operation on levels :假设： In general the different sources of noise are not in phase通常不同声源的噪声有不同的相位 they are incoherent sources. Incoherent sounds add together on a linear energy (pressure square) basis.它们是互不相干的声源，不会发生干涉现象，可以进行能量叠加。 When sources of the same frequency are combined, phase angle between the sounds must be taken into account.当同频率的声源相结合，两者之间的角相位就可以被计算。 When the phases are random, the equation reduces to the incoherent case: 当这个相位是任意的时候：;;;Source of noise to be evaluated Ls;;;;;;;;;;;;;