Around a decade and some change ago, SONY entertainment patented the use of ultrasound as a virtual reality inducer. One would wear a helmet that sent ultrasonic waves through certain parts of the brain to illicit a certain emotion, or sensation.
Today, they are still studying how ultrasonic stimulation affects sensory input. In the future, it is very likely that this stuff will be used for the treatment of various diseases and peripheral nervous disorders. Excellent. Medicine needs a boost like that.