From Stephen Chen's 9-19-19 South China Morning Post article entitled "Chinese Scientists Develop Handheld Sonic Weapon for Crowd Control":
China has developed the world’s first portable sonic gun for riot control, the Chinese Academy of Sciences said.
rifle-shaped instrument, which was jointly developed with military and
law enforcement, is designed to disperse crowds using focused waves of
low frequency sound, the academy's Technical Institute of Physics and
Chemistry website said on Wednesday.
device’s “biological effect” would cause extreme discomfort, with
vibrations in the eardrums, eyeballs, stomach, liver, and brain,
dating to the 1940s found that low frequency sound energy could,
depending upon intensity and exposure, cause dizziness, headaches,
vomiting, bowel spasms, involuntary defecation, organ damage and heart
weapons are typically large and have to be mounted on vehicles. Until
the Chinese development, which has no moving parts, they were powered by
electricity to drive a magnetic coil to generate energy. This meant
they needed a large and stable source of power....