Doubling

What it means

One speaks of doubling when a note of a chord occurs in more than one voice — mostly an octave apart. This becomes necessary as soon as there are more voices present than chord tones: a four-part setting over a triad must give one of the three notes to two voices.

Musical use

Which note is doubled is not a matter of indifference. As a rule, in root position the root is doubled, because it supports the sonority most firmly. The third is doubled with restraint, because it determines the mode and easily stands out when doubled; the leading tone is not doubled, since both voices would then have to strive toward the root and parallel octaves would result. With the six-three chord, doubling the third in the bass is likewise to be avoided, while with the six-four chord the bass is as a rule doubled.

Behind these rules stands no formalism but consideration for sound and voice leading: doublings easily produce forbidden parallels, and a clumsily doubled note makes the chord heavy or lopsided.

In orchestration, doubling means something related but broader: two instruments carry the same line, in unison or in octaves. This serves carrying power and above all timbre, for a new colour arises from the mixture. A doubled voice gains considerably more weight than the number of notes would suggest.

In four-part writing, one mostly doubles the root in root position, because it is sonically the most stable. With six-three chords, one doubles the root or the fifth, more rarely the third. The leading tone and dissonant notes such as the seventh are as a rule never doubled, because otherwise both voices would demand the same resolution and parallels would result. In orchestration, doubling also designates a further instrument playing along with a voice in unison or in the octave.

Performance practice

When balancing, take care that a doubled line does not take over — two instruments on the same voice sound more than twice as present. With octave doublings, match articulation and vibrato, or two lines arise instead of one colour. And intonate octaves with particular care; deviations stand out most strongly there.