The 最大 deviation from the average or equilibrium 值 of any repeatedly changing quantity such as the 位置 of a 颤 对象 压力 velocity 电压 current and many others The 振幅 of a 声音 波 is the 最大 amount by which the instantaneous 声音 压力 differs from the 周围 压力 The variation of 最大 振幅 over 时间 is called the 包络 of the 声音 源 Barry Truax - Handbook for Acoustic 生态学 CD-ROM Edition Cambridge Street 出版 1999 - CSR-CDR 9901