Changing the rhythm

At 96 beats per minute, eight bars of four beats last exactly 20 seconds.

Pitch is only half of a melody. The other half is rhythm: when each note starts and how long it lasts. Play the same seven notes with two different rhythms and many listeners will think they are two different tunes. This unit explains beats, bars and note lengths, and then uses the song maker to give one set of notes a new rhythm.

Beats, bars and tempo

The beat is the steady pulse you tap your foot to. Beats are grouped into bars (also called measures). The songs in this course are in 4/4 time: four beats in each bar, with beat 1 a little stronger than the others. Tempo is the speed of the beat, measured in beats per minute, or bpm. At 60 bpm one beat lasts one second; at 120 bpm it lasts half a second. In general, one beat lasts 60 divided by the bpm, in seconds. The tempo slider in the song maker runs from 60 to 160 bpm.

BackgroundFor most of music history, composers did not write down exact speeds; the right tempo was thought to be obvious from the music. In 1815 Johann Nepomuk Maelzel patented the metronome, a clockwork pendulum that clicks a set number of times per minute. Beethoven took it up quickly, and in 1817 he added metronome marks to his first eight symphonies, which had already been published. Musicians still argue about those marks, because many of them feel very fast. One study in 2020 suggested that he may have read the scale on the wrong side of the sliding weight.

Note lengths

In 4/4, a quarter note lasts one beat, a half note two beats, a dotted half three beats and a whole note four beats, a full bar. An eighth note lasts half a beat, so two eighths fill one beat. A dot after a note adds half its length again: a dotted quarter is one and a half beats. Silence counts too. A rest is a measured gap, and on the grid it is simply an empty cell. Rests let a phrase breathe and make the next note land with more force.

Six ways to fill one 4/4 bar: 1 whole note; 2 two halves; 3 dotted half and quarter; 4 four quarters; 5 four eighths and two quarters; 6 dotted quarter, eighth and half.

Note	Beats in 4/4	Seconds at 96 bpm	Cells (split beats on)
eighth	1/2	0.3125	1
quarter	1	0.625	2
dotted quarter	1 1/2	0.9375	3
half	2	1.25	4
dotted half	3	1.875	6
whole	4	2.5	8

Same notes, new rhythm

A quick way to write a second phrase is to keep the notes and change the rhythm. Lengthen the first note and shorten the next one, and a plain walk turns into a lilt. Turn two quarter notes into four eighths and the line gets busier. Hold the last note of a phrase for a whole bar and it sounds like an ending. Long notes on strong beats feel stable; short notes and notes that start between beats push forward. A melody that uses only quarter notes is a good draft, but it rarely sounds like a song yet.

Try it

This grid has Split beats switched on, so each cell is an eighth note and a bar has eight cells. Bars 1 to 4 walk in plain quarter notes. Bars 5 to 8 use the same pitches with a new rhythm: a dotted quarter and an eighth, two quick eighths into a long G, a run of eighths and a whole-bar C. Play it and compare the halves; the Rhythm line in the panel counts each kind of note. Then change bars 1 to 4 yourself by dragging notes longer or splitting them, and try the tempo slider.

Drag to turn. Scroll or pinch to zoom.

Split beats on: one cell is an eighth note. Bars 5 to 8 repeat the pitches of bars 1 to 4 with a new rhythm.

Whole 4, dotted half 3, half 2, quarter 1, eighth one half. A dot adds half again.

At 120 bpm, how many seconds does one beat last?
At 96 bpm, how many seconds do 8 bars of 4/4 last?
How many beats does a dotted half note last in 4/4?
How many eighth notes fill one 4/4 bar?
At 80 bpm, how many seconds does a half note last?
A dotted quarter note lasts...
- 1 1/2 beats
- 2 beats
- 3/4 of a beat
On the song maker grid, what is a rest?
- An empty cell
- A pale note
- A chord
Which change usually makes the end of a phrase sound finished?
- Holding the last note longer
- Adding fast eighths
- Starting the last note between beats
Who patented the metronome in 1815?
- Johann Nepomuk Maelzel
- Ludwig van Beethoven
- Wolfgang Amadeus Mozart
You keep the notes and change only the rhythm. What does the listener hear?
- A related but new phrase
- Exactly the same phrase
- A different key

Key points

4/4: four beats per bar, beat 1 strongest.
One beat lasts 60 / bpm seconds; at 96 bpm, 8 bars last 20 s.
Whole 4, dotted half 3, half 2, quarter 1, eighth 1/2; a dot adds half.
Empty cells are rests; same notes with a new rhythm make a new phrase.

Sources for this course (13)

Fundamentals of Music Theory, UMass Amherst, Unit 14 Melody: repeated notes, conjunct (stepwise) and disjunct (skip, leap) motion, melodic contour (fundamentalsofmusictheory.umasscreate.net/unit-14)
Humanities LibreTexts, Music Appreciation II 1.1 Melody: contour, conjunct and disjunct, range, motive (human.libretexts.org)
Open Music Theory (Lavengood, Peterson et al., CC BY-SA)
chapters Roman Numerals (uppercase major, lowercase minor, I ii iii IV V vi vii° in major)
Introduction to Harmony, Cadences and Phrase Endings (authentic cadence V-I, half cadence ends on V)
The Phrase, Archetypes and Unique Forms (period = antecedent ending with a weaker cadence, often a half cadence, and consequent ending with a stronger one; antecedent often four bars)
Glossary (sequence model and copy) (viva.pressbooks.pub/openmusictheory)
Robert Hutchinson, Music Theory for the 21st-Century Classroom 7.4 Cadences and 11.4 Phrase (most phrases are four bars) (musictheory.pugetsound.edu/mt21c)
musictheory.education 2.14 Degrees I, IV and V: tonic, subdominant, dominant
Duke University Sonic Dictionary, Melodic Sequence (a motive repeated at a higher or lower pitch)
Wikipedia and IMSLP, Twelve Variations on "Ah vous dirai-je, Maman" K. 265/300e (French melody first printed 1761; Mozart, 1781 or 1782, Wolfgang Plath's dating; first published 1785)
PLOS ONE 2020, Martin-Castro and Ucar, "Conductors' tempo choices shed light over Beethoven's metronome" (Maelzel patented the metronome in 1815; Beethoven added marks to his first eight symphonies) and Boston Baroque, Martin Pearlman (the marks were added in 1817)
All melodies in the lessons are written for this course except the French folk melody of 1761, which is in the public domain. Timing values computed: one beat = 60 / bpm seconds.

Checked: 2026-10-17