Ultrasonic Speaker Diy Is It True That Ultrasound Generates Heat?

Is it true that ultrasound generates heat? - ultrasonic speaker diy

If so, how much heat can be generated in say, a glass of water? and how long would it take to reach the boiling point?
I read an article about a type of building a device for heating water using ultrasonic waves. Is it possible to do and how long it would take to do? What kind of drive would have to do this? I do not think a speaker can be used ...