次声,是一种人耳听不到的声波,人们往往把声波频率在每秒钟16次以下的部分称为次声波。如果用科学仪器测定,通常人们耳朵能听到的声音,是每秒钟振动频率在20赫兹到2万赫兹的声音,高于2万赫兹的称为超声,低于20赫兹的称为次声。次声波的基本性质是频率低、波长长,传播过程不易被介质吸收,在大气中可传播得很远。 The infrasound, which is a kind of sound wave that the human ear can not hear, is often referred to as infrasound in the part whose sound wave frequency is under 16 times per second. In the case of scientific instruments, the sound normally heard by the human ear is that sound which vibrates at a rate of 20 Hz to 20,000 Hz per second, what is called ultrasound which is higher than 20,000 Hz and which is called infrasound which is lower than 20 Hz, . The basic nature of infrasound is low frequency, long wavelength, the propagation process is not easily absorbed by the medium, can be spread far in the atmosphere.