What is the frequency range typically considered to be ultrasonic?
Choose only ONE best answer.
A
Less than 20 Hz
B
Between 8 kHz and 15 kHz
C
Greater than 20 kHz
C
Greater than 20 kHz
Choose only ONE best answer.
A
Less than 20 Hz
B
Between 8 kHz and 15 kHz
C
Greater than 20 kHz
Greater than 20 kHz