pitch
The perceived highness or lowness of a sound, determined by its frequency.
In Depth
Pitch is the perceived frequency of a sound — how high or low it sounds to the listener. It is determined by the rate of vibration: a string vibrating at 440 times per second produces the note A4, the standard tuning reference used by most Western orchestras today.
The relationship between pitch and frequency is logarithmic — each octave doubles the frequency. Human hearing spans roughly 20 Hz to 20,000 Hz, while the piano covers approximately 27 Hz to 4,186 Hz. Perfect pitch (the ability to identify any note without a reference) is rare, but relative pitch (the ability to identify intervals) can be developed through training.
Concert pitch (A=440 Hz) wasn't standardised until 1955. Before that, orchestras tuned to wildly different pitches — some as low as A=415 and others as high as A=460.