How can the same notes become different music?

A speaker makes sound by moving its cone back and forth, disturbing nearby air. Those disturbances travel outward as changing pressure. The cone can repeat its motion hundreds of times during one note. The number of cycles per second is its frequency; a faster repeating vibration generally produces a higher pitch.

Rhythm describes a different layer of timing: when notes begin, how long they last and where silence falls between them. A 200 Hz note contains 200 vibration cycles in each second that it continues. Playing that note four separate times instead of twice changes the sequence of events without requiring a different vibration frequency inside each note.

A musical string adds another relationship. Waves reflect from its fixed ends and overlap with waves traveling the other way. Patterns that fit the string can reinforce into standing waves, with some points remaining still. In an ideal string, the allowed frequencies are whole-number multiples of the lowest one. Their mixture helps give an instrument its characteristic sound.

A melody can keep the same rhythm while its notes move higher and lower, or keep the same pitches while their spacing changes. Vibration size affects another feature associated with loudness. Pitch, rhythm and loudness can vary together, but each names a different part of the sound. Separating them explains how the same few notes can become recognizably different music.