In music, the pitch of a note means how high or low the note sounds. For example, a violin usually has a higher pitch than a string bass. Pitch mostly depends on the frequency of the sound — how fast the air vibrates back and forth. In physics, frequency is measured in a unit called Hertz. A note that is vibrating at 261 Hz will be caused by sound waves that vibrate at 261 times a second. This will be Middle C on the piano.
Not all musical instruments make notes of a certain pitch. Many percussion instruments like drums, triangles and cymbals are instruments used for rhythms. They do not play tunes because they have no definite pitch (although often a definite pitch can just be heard when listening carefully.)
Some musicians have a sense of absolute pitch or perfect pitch. This means that they always know what note is being played, even without comparing it to another note. Having a sense of absolute pitch does not necessarily make someone a good musician, although it can be very useful.
Pitch is not exactly the same as frequency. Frequency is used as a scientific means for measuring and changing sound and its possible pitches. Pitch is a more psychological quality. It depends on how the ear perceives sounds, and how the brain interprets them.
- Pitch (music) Citizendium