Common tone

In music a common tone is a pitch class that is a member of, or common to, a musical scale and a transposition of that scale, as in modulation (Johnson 2003, p.42). Six of seven possible common tones are shared by closely related keys, though keys may also be thought of as more or less closely related according to their number of common tones.

Related Topics:
Music - Pitch class - Musical scale - Transposition - Modulation - Closely related key

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In diatonic set theory the common tone theorem describes that scales possessing the deep scale property share a different number of common tones for every different transposition of the scale. However many times an interval class occurs in a scale, "deep" scales containing each interval class a unique number of times, is the number of common tones under transposition by that interval class. Thus modulation to the dominant, transposition by a perfect fifth, includes six common tones as there are six perfect fifths in a diatonic scale. However, transposition by the tritone includes two common tones. (ibid)

Related Topics:
Diatonic set theory - Deep scale property - Interval class - Perfect fifth

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See also: Voice leading.

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