To disperse crowds and prevent rioting, various forms of non-lethal weapons (NLW) are used. Among these, interestingly, is sound. Known as an acoustic or sonic weapon, infrasound (superlow frequency) and ultrasound (super-high frequency) greatly affect human ears. They can disorientate a target and have psychological effects as well as physical effects of nausea and damage to blood vessels. Explanation Ultrasound can be increased to 120 decibels (the same volume as a jumbo jet taking off), which is considered the human pain threshold. In contrast, infrasound feels like a damaging vibration or pressure wave, as it’s at a frequency too low for humans to hear. When exposed to high levels of sound, the influx of energy has a painful effect on the body. As well as huge decibels of volume, the variations in frequency can also cause damage. For instance, an infrasound of seven or eight Hertz can rupture blood vessels. Certain types of sound within the frequencies we are able to he