Wavetek And Audiocart - Frequency Range Of Hearing
To demonstrate the approximate frequency range of human hearing.
Oscillator with amplifier and speakers on Audio Cart.
The audio system has a useful range from below 20 Hz through well above 20 kHz, although it doesn't do well below about 40Hz. Have people raise their hands when they hear the tone to see the hearing range of the group. Turn it off and tell them the frequency is about 20 kHz; you will find out who the liars are or those with tinnitus. Note also that, keeping the intensity constant while sweeping from 1 kHz to 10 kHz, people hear the tone as louder around 3-5 kHz because the ear is most sensitive in that frequency range.
Arthur Taber Jones, A Simple Demonstration of the Effect of Intensity upon Pitch, AJP 5, 139 (1937).