Pitch: The highness or lowness of a sound, such as the different notes produced on a piano.
Frequency: The number of complete cycles of a sound wave that occur in one second. In relation to a piano, this is what determines the pitch of each note played.
Auditory Perception: The brain's ability to interpret and make sense of sounds received from the ears. It plays an important role in appreciating the different musical notes produced by a piano.