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Pitch

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-212

2025-11-23

585

The pitch of a tone depends upon the number of vibrations made per second by the vibrating body that produces it, the pitch being relatively high when the vibrations are rapid, and low when they are slow.

Since the velocity of sound is the product of the wave length and the number of vibrations per second, it is evident that the wave length is greater for tones of a low pitch than for those of a high pitch. It is also evident that as the period (or length of time of one vibration) becomes greater the pitch becomes lower.

When the corner of a stiff card is drawn across the cover of a cloth-covered book, a certain sound will be heard. On moving the card more rapidly, the pitch of the sound produced is made higher than at first.

The speed at which a circular or "buzz" saw is running can be judged by the pitch of the tone which it gives when sawing a log. A knot in the log lessens the speed and lowers the pitch of the tone.