https://www.youtube.com/watch?v=bCm6VpCE9Qc&t=4s
Noise VS Note
Both noise and notes are mixtures of sound waves at different frequencies. A note is made up of a ripple pattern which repeats itself over and over again in an ‘ordered’ way. While a noise is made up of individual ripples which have no relationship to each other and do not repeat - and so are ‘disordered’.
If an object moves, it causes a disturbance in the surrounding air which ripples out as soundwaves. If the object vibrates with a fast and repeating pattern, like a string, then the sound waves will be evenly-spaced and regular; that is, the air particles are squeezed together into evenly-spaced waves. These evenly-spaced, regular sound waves are heard as notes with distinct pitches.
But, if you drop a vase or slam a door shut, you hear a noise which is made up of a lot of unrelated frequencies with no repeating pattern – and so will be a heard as noise with no defined pitch. To be a note, it doesn’t really matter how complicated the individual ripples are, as long as the pattern repeats itself.