Pitch

Pitch is the characteristic of a sound determined by the frequency of vibration of the sound waves. High-pitched sounds have higher frequencies than low-pitched sounds. When violin players tune their instruments, they adjust each string so that it will vibrate at the desired frequency.

The pitch of most sounds we hear is actually due to a blend of various frequencies. The sounds produced by a musical instrument, a whistle, or a siren have several frequencies at the same time. The lowest frequency, called the fundamental frequency, is produced by an object vibrating as a whole. The higher frequencies, called harmonics or overtones, are produced by an object vibrating in parts. For example, a violin string vibrates as a whole, and in halves, thirds, and so on at the same time. The overtones are whole number multiples of the fundamental frequency. A tuning fork produces a sound wave of a single frequency. So do pitch pipes, which are used to get the correct number of vibrations for certain notes. Physicists distinguish between pitch and frequency. They use the term pitch to refer to the psychological judgment of frequency, which depends on the loudness of the tone.

The notes we play and sing today did not always have the same pitch. Composer George Frideric Handel tuned the A above middle C as low as 422.5 vibrations a second. Today, the standard for pitch is the Stuttgart, or concert, pitch. It places A at 440 vibrations a second.

Contributor: Thomas A. Griffy, Ph.D., Prof. of Physics, Univ. of Texas, Austin.

Pitch

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