人类生活在一个充满噪声的世界。都市中人的鼎沸声,马路上车辆的喧闹声,车间里机器的轰鸣声,……这类可闻噪声的频率范围为20赫到20千赫,已被国际上列为七大公害之首。然而,还有一类人耳听不见的“噪声”,即频率高于20千赫的超声波和低于20赫的次声波(约10-4～20赫)。目前,人们 Human beings live in a world full of noise. The buzz of urban people, the loud noise of vehicles on the road, the roar of machines in the workshop ... The frequency of such audible noise ranged from 20 Hz to 20 kHz and was internationally recognized as the top of the seven public hazards . However, there is also a category of “invisible” noise in the human ear, ie, ultrasound frequencies above 20 kHz and infrasound waves (about 10-4 to 20 Hz) below 20 Hz. At present, people