Metre change

Usually a piece keeps its time signature from beginning to end. But there are many cases in which the time signature changes: because a text with irregular stresses is being set, because a section is to be shorter or longer than the others, or because the composer wants to create a feeling of breadth or narrowness. The new time signature is then written at the beginning of the first bar that needs it, so after the barline.

What stays the same, what changes

Mostly the basic beat stays unchanged: a quarter note lasts as long after the change as before, only the number of quarter notes in the bar changes. That sounds like a simply shortened or lengthened bar, and the pulse runs on without a break. It is different when the beat changes too, for example if an eighth note after the change is to be as long as a quarter note was before. Then the notation has an equation (♪ = ♩) or the marking l'istesso tempo.

An example from the sheet music archive

The table shows how the choral setting “Gladsome Light” changes time signature. Bar 6 with six quarter notes is longer than its neighbours, bar 10 with three quarter notes shorter. The quarter-note basic beat stays the same.

Hearing a metre change

A metre change is clear in sound only if you consciously count the stress along. Compare the two staves above: in 4/4 the next downbeat comes after four beats, in 3/4 already after three. In playing you simply keep counting at the same tempo and follow the new time signature.

• Gladsome Light SATB choral setting with guitar chords · 2 pages

  The choral setting begins in 4/4. Bar 6 is in 6/4, then 4/4 again, bar 10 is in 3/4 and bar 11 is back in 4/4. The table above gives these first eleven bars as they are printed on page 1. The tempo marking above the start reads “Не очень медленно” (Russian for “not very slowly”).