Rhythm & Metre

Pulse, rhythm and metre do different jobs

A pulse is a recurring reference beat. A rhythm is an arrangement of durations and events around it. Metre groups beats, often with a recurring pattern of emphasis. You can draw these relationships without making a sound. A row of evenly spaced boxes can represent the pulse, while marks inside or across boxes represent the rhythm.

In common Western notation, a crotchet is also called a quarter note and a quaver an eighth note. Their names describe relative durations: two quavers occupy the duration of one crotchet. They do not specify seconds until a tempo and beat unit are given. A rest marks a duration without a note beginning or continuing in that part.

Worked example: account for every half-beat

Here is an invented four-beat bar with a crotchet pulse: one crotchet, two quavers, a crotchet rest, then one crotchet. Count its half-beat units as 2 + 1 + 1 + 2 + 2 = 8. Eight half-beats make four beats. At a tempo of 60 crotchet beats per minute, each beat lasts one second, so this bar lasts four seconds.

Now move the rest to beat two and the two quavers to beat three. The total is still four beats, but note beginnings occur at different moments. Length alone cannot identify the rhythm. To compare versions fairly, hold the pulse and tempo constant and describe exactly which events moved.

Six divisions can have two different groupings

In a simple 3/4 example, three crotchet beats can each divide into two quavers: 2 + 2 + 2. In a compound 6/8 example, two dotted-crotchet beats usually each divide into three quavers: 3 + 3. Both bars contain six quaver durations, but the usual beat grouping differs. Counting six marks is therefore not enough to explain their metre.

A time signature is a notation convention, not an ordinary fraction that you cancel down. It also does not dictate every accent a performer might make. This introduction describes selected Western conventions; other traditions and performances may organise time differently.

Use a score as an explanation

A useful private score states its key: what one box means, how a sound continues, and which marks indicate silence. Someone looking at it should be able to distinguish an intentional gap from a missing instruction. You can revise the key when it fails to describe an idea. Accuracy here means making a chosen pattern understandable, not keeping time perfectly or demonstrating musical ability.