PE is related to the ability to do work, If an item is sitting on a shelf
it has potential energy relative to its position on the floor, However, if the object were to fall it would hit the floor with a KE equal to the PE that it had sitting on the shelf.
Sounds are caused by compressional waves in the air - when a piano key is struck or a TV is turned on, then compressional waves are produced in the surrounding air due to a disturbance. The human ear recognizes the disturbed air as due to the object that created the disturbance.
