idea
Sound in the air
A vibrating string pushes the air next to it, squeezing it and letting it go. These small changes of pressure pass from one bit of air to the next and travel outwards at about 343 metres per second. That travelling pattern is sound. The air itself does not travel to your ear, only the pattern does. The size of the pressure changes decides how loud the sound is, measured in decibels. The distance from one squeeze to the next is the wavelength: about 78 cm for the A at 440 Hz, and more than 12 metres for the lowest note of a piano.