I'm writing a song that changes to 7/8 and I'm wondering if or when dotted rests are appropriate (assuming that dotted rests are appropriate for compound meters).
Elaine Gould's Behind Bars addresses this question indirectly, in two places:
- p. 160: "Grouping rests according to the metre"
Rests must be grouped to clarify the divisions of the bar. Rests with the duration of one or more beats may start only on a beat.
- p. 178: "Metres of variable stress"
Where possible, bar division is indicated by beam grouping or by the particular division of longer notes and rests.
From those principles
It's fine to use dotted rests as long as they are consistent with the pulse subdivisions within the measure. For example, if 5/8 time breaks down into a 3+2 beat structure, a dotted quarter rest in the first part of the measure is okay, but not in the second part. Similarly, in a 2+3 context, a dotted quarter rest would be fine in the latter half of the measure, but not at the beginning.
Smaller rests (e.g., dotted eighth rests) are fine as long as they don't cross the beat boundaries.
Larger rests (e.g., dotted half rests) are generally broken down into two or more smaller rests that delineate the pulse pattern.