tone. In music, a tone is distinguished from noise by its definite pitch, caused by the regularity of the vibrations which produce it. Any tone possesses the attributes of pitch, intensity, and quality. Pitch is determined by the frequency of the vibration, measured in cycles per second; intensity (or loudness) is determined by the amplitude, measured in decibels. Quality is determined by the overtones (see harmonic), the distinctive timbre of any instrument being the result of the number and relative prominence of the overtones it produces. When two fairly loud tones of equal volume but different pitch are sounded together, a fainter resultant tone, representing either the sum of their two rates of vibration (summation tone) or the difference (difference tone) may be heard. The term whole tone or whole step refers to the interval of a major second or its equivalent; the term half tone, semitone, or half step denotes a minor second (see scale).
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