Music is all about tones.
As soon, as something moves in the air in regular intervals and the waves in the air hit your ear - you perceive it as a tone. If these waves cycle faster, with shorter intervals, you hear a higher tone. On the opposite, you perceive slower waves cycles as a lower tone.
A large amount of your brain is dedicated analysing all the waves in the air around you and trying to interpret them as tones. That is the reason, why you can even think to hear tones in random noise.
Therefore, a tone is repeating air movement over time.