Rhythm, Pulse, Tempo, and Meter

Four words come up again and again when people talk about musical time: rhythm, pulse, tempo, and meter. They are related but not interchangeable, and mixing them up gets in the way of both listening and practicing. Each one describes a different aspect of how music organizes itself in time.

Pulse: the beat we feel

The pulse is the regular series of beats we perceive in a piece of music, the one that makes someone nod along or tap a foot without thinking. It works as the internal clock of the piece. It can be played explicitly, for example by the bass drum, or merely implied by the other voices.

An important point is that the pulse is a perception, not necessarily a sound. In many pieces no instrument marks every beat, and yet the listener still feels it. It is also common for the pulse not to be the fastest note value in the music: it is the counting unit over which the notes are distributed.

To find the pulse, listen to a song and try to clap along steadily without speeding up. If you keep the same speed all the way through and the clapping fits naturally, you have found it.

Tempo: the speed of the pulse

The tempo tells you how fast the pulse is. It is usually measured in beats per minute, abbreviated BPM. A metronome set to 60 clicks once per second; at 120, it clicks twice per second.

In the concert tradition, tempo appears in the score through Italian terms such as:

• Largo and adagio: slow;
• andante: at a walking pace;
• moderato: moderate;
• allegro: fast and lively;
• presto: very fast.

These terms describe character rather than an exact speed. Only from the early nineteenth century, with the spread of the metronome, did composers begin to give numerical values more often. Beethoven is one of the first major figures to have recorded metronome markings for his works.

Tempo can also change within a single piece. Terms such as accelerando (gradually speeding up) and ritardando (gradually slowing down) guide the performer. Rubato, an expression that suggests "stolen" time, refers to the small liberties a musician takes with a rigid pulse, pushing notes closer together or stretching them apart to add expression.

Meter: grouping the pulses

If the pulse were always identical, music would sound like a monotonous string of clicks. What organizes our perception is hierarchy: some beats are naturally stronger and others weaker. Meter groups these beats into repeating blocks, which are separated in the score by vertical lines called bar lines. Each block is a measure.

The time signature, written at the beginning of the staff, has two numbers:

• the top one tells how many beats there are in each measure;
• the bottom one tells which note value equals one beat (4 for a quarter note, 8 for an eighth note, and so on).

Some examples:

1. 2/4: two quarter-note beats. The first is strong and the second weak, which gives the feeling of a march.
2. 3/4: three quarter-note beats, with the accent on the first. This is the typical meter of the waltz.
3. 4/4: four beats, with the main accent on the first and a secondary accent on the third. It is the most common meter in popular music.
4. 6/8: six eighth notes, usually felt in two groups of three, which produces a rolling, triple-based sway.

Notice that the meter does not determine speed. A slow waltz and a fast waltz share the same 3/4 meter but have different tempos.

Rhythm: the pattern of durations

Rhythm, in the strict sense, is the pattern of durations of notes and rests. While the pulse is regular, the rhythm is what is drawn on top of it: long notes, short notes, groupings, and silences. Two melodies can share the same pulse and the same meter and still sound quite different because their rhythms are different.

A few rhythmic devices deserve special mention:

• Syncopation: a note that begins on a weak beat and extends across the strong beat, displacing the accent. It is a central element in many popular styles.
• The dot: a dot next to a note lengthens it by half. A dotted quarter note, for example, lasts a quarter note plus an eighth note.
• Tuplets: groups that divide the beat differently from the usual way, such as the triplet, which fits three notes into the space of two.

Percussion instruments are the most obvious keepers of rhythm, as shown in how percussion instruments are classified. In practice, the parts of a drum kit tend to divide up the work: the bass drum and snare define much of the pattern, while the cymbals mark subdivisions, as the article on the parts of a drum kit explains.

Simple and compound meters

Meters fall into two large groups, depending on the natural subdivision of the beat. In simple meters, such as 2/4, 3/4, and 4/4, each beat divides into two equal parts: a quarter note becomes two eighth notes. In compound meters, such as 6/8, 9/8, and 12/8, each beat divides into three parts: the beat corresponds to a dotted note value, and the triple subdivision creates a rounded swing, close to that of a barcarolle or a gigue.

There are also asymmetrical meters, such as 5/4 and 7/8, in which the beats are grouped unevenly, for example as three plus two. They appear in twentieth-century concert music as well as in folk traditions from many parts of the world. The sense of imbalance they create is exactly what makes them interesting.

How to train your sense of time

One effective exercise has three stages. First, set the metronome to a comfortable speed and clap on every click. Next, count the beats of a measure out loud, stressing the first one more strongly. Finally, try clapping only on the first beat while keeping the others in your head.

When reading music, the habit of counting out loud before you play helps fix the connection between pulse and note values. This work goes hand in hand with reading sheet music, in which duration appears in precise symbols. And because rhythm interacts with the melodic line and the accompaniment, it is worth seeing how it combines with melody, harmony, and timbre.

Another good habit is to practice difficult passages at half speed with the metronome on. Slow practice exposes uneven beats that are easy to hide at full speed, and raising the tempo a few clicks at a time builds accuracy without tension.

Where to Go From Here

Choose three songs you know well and, for each, find the pulse, the likely meter, and the approximate tempo in BPM using a metronome. Write down what changes from one to the next. When you want to check what you have learned, test your knowledge in the quiz.