An Invisible Wave:
A Short Explanation of Sound

Sound consists of a pressure wave, varying above and below the ambient pressure. Properties such as frequency, wavelength, amplitude, speed and direction are used to characterize these waves.

The amplitude, or sound level, corresponds to the loudness of sound, and is measured in decibels (dB) whereas the frequency, which corresponds to pitch, is measured in cycles per second – also called hertz (Hz).

The quietest sounds that humans are able to hear correspond to
a hearing level of approximately 0 dB, the average hearing threshold.