Which of the following statements regarding soundwaves is incorrect?
1
The audible range of sound for human beings extends from about 20 Hz to 20000 Hz
2
Frequencies of sound waves higher than 20 KHz are called ultrasonic sound waves
3
Ultrasound is produced by dolphins, bats and porpoises.
4
Earthquakes produce high frequency ultrasound before the main shockwaves begin which possibly alerts the animals.