3.27 understand that the frequency range for human hearing is 20 Hz – 20,000 Hz

3.27 understand that the frequency range for human hearing is 20 Hz – 20,000 Hz

An average person can only hear sound that have a frequency higher than 20Hz but lower than 20000 Hz. This spread of frequency is called audible range. Frequency higher than 20000 Hz which cannot be heard by humans are called ultrasounds. Frequency lower than 20 Hz that cannot be heard by humans are called infrasound.