piano

i was playing some Beethoven on my keyboard the other day and realized that there was a lot of physics involved in the music i was making. Each time i pressed down on a key, sound waves were produced and came out of the speakers. These longitudinal mechanical waves moved through the medium, air, to my ear. i played the note A, and remembered that A has a frequency of 440 Hz. i moved down the keyboard and played another A. This note was an octive lower and therefore had a frequency of 220 Hz.