We need a vibrating body for the production of sound. But we cannot hear the sound of all vibrating bodies.

⇒ Range of frequency for every vibrating body is different.

⇒ The sounds of frequencies less than about 20 vibrations per second cannot be heard by us. Such sounds are called inaudible sounds.

⇒ The sounds of frequencies higher than about 20,000 vibrations per second are also cannot be heard by us.

⇒ The range of frequency which is audible to us is 20 Hz – 20,000 Hz. This range is called audible range.