Sonic Attacks' in China could just be ultrasonic surveillance

The transcript discusses fears of sonic weapons due to abnormal sensations of sound and pressure. Researchers from the University of Maryland theorize that illnesses may result from surveillance gear being too close together. Ultrasonic devices can interfere with each other, causing intermodulation distortion, which produces audible sounds similar to those reported by patients. These devices can also cause cavitation damage by forming bubbles in body fluids, tissues, or cells.

What audible sounds do patients claim to hear when exposed to ultrasonic devices?

How can ultrasonic devices cause cavitation damage in the body?