Sound

Sound refers to fluctuations in air pressure caused by a vibrating object that occur at a frequency and amplitude perceptible to the ear. The changes in air pressure can, in some cases, cause analogous variations in some other medium such as water or metal, such that the sound can travel through walls and other materials and be propagated back into the air.

Harmonic tones are made when partials (individual frequencies that when grouped together make a harmonic tone) are combined. When the partials are integers of each other, then they make a ''harmonic spectrum. ''