Ultrasonic waves are those sound waves having frequency __________?
Options:
- A. between 20 hertz and 1000 hertz
- B. between 1000 hertz and 20000 hertz
- C. less than 20 hertz
- D. more than 20 kilohertz
View Answer
D. more than 20 kilohertz
D. more than 20 kilohertz