The 率 of 重复 of the 周期 of a 周期 quantity such as a 声音 波 Thus 频率 is the 相反 of the period More 通常 频率 can be thought of as the 率 of change of 相位 频率 is denoted by the 符号 f and is 测量 in 赫兹 赫兹 - formerly called 周期 每（一个） second cps or c/s - kilohertz kHz or megahertz mHz The only 声音 which consists of a single 频率 is the 纯 正弦 音 All other 声音 are 复（杂） consisting of a 数 of 频率 of greater or lesser 强度 The 频率 content of a 声音 is its 频谱 The 主观 感觉 of 频率 is called 音高 That is 频率 is an acoustic variable whereas 音高 is a psychoacoustic one 源 Barry Truax - Handbook for Acoustic 生态学 CD-ROM Edition Cambridge Street 出版 1999 - CSR-CDR 9901