Rhythm decoder: how to count a rhythm, then tap it back

How to count a rhythm

Counting turns notation into timing. You say the beats — 1 2 3 4 in 4/4 — and when a note is shorter than a beat you say the parts of the beat too: 1 & 2 & for eighth notes, and 1 e & a for sixteenths. Every count is said whether or not a note starts on it; you play only on the counts where one does. The decoder writes the counts you play in bold, the counts a held note lasts through in brackets, and rests in grey. It only counts as finely as the rhythm needs: four quarter notes are 1 2 3 4, not 1 e & a.

Take a dotted quarter and an eighth, then two quarters. Count it 1 (&) (2) & 3 (&) 4 (&) and tap on 1, 2&, 3, 4. The dot makes the quarter note on beat 1 last as long as three eighth notes (counted 1 & 2), so the next note comes on the & of 2. Reading the figure as “long, short” is not enough to place that eighth; counting the & is.

How rests change the count

A rest is counted exactly like a note — it takes its place in the bar — but you do not play on it. Rests are where people rush: with nothing to play, the next note comes in early. In the bar “beat 4 starts with a rest”: Beat 4 begins with an eighth rest, then the note enters on the & of 4. Say the “4” out loud, silently play nothing, and the note lands on the &.

Do you tap again on a tied note?

No. A tie joins two notes of the same pitch into one sound, so the second note is held, not played again. Two quarter notes are two taps; a quarter tied to a quarter is one tap held for two beats. Written, they look almost the same — which is why the decoder shows the difference on the grid (3 taps against 2), plays it, and, if you tap the tied note again, tells you so. See dotted notes and ties for how both lengthen a note.

How to count syncopation

Syncopation puts a note where the beat does not expect it — most clearly, a note that starts between beats and is held through the next beat, so that beat gets no new attack. The decoder only calls a note syncopated when it does exactly that. Count the subdivision and the figure becomes ordinary arithmetic: 1 (&) 2 & (3) & 4 (&). The tie carries the note from the & of 2 through beat 3: tap once, on 2&, and hold through 3. That is syncopation: the note starts between beats and the beat itself gets no new attack. Notes that simply fall on the & after a rest are described as entries between beats rather than labelled. The syncopation lesson covers why it only works against a steady pulse.

6/8: two beats, counted in six

6/8 is not 3/4 played faster. A bar holds six eighth notes in two groups of three, so you feel two beats — each a dotted quarter — and count all six: 1 2 3 4 5 6, leaning on 1 and 4. The tempo in 6/8 is the dotted quarter’s, and the count-in clicks all six eighths with the two beats accented, so the three-way split is heard before you start. More in time signatures, and hear 3/4 against 6/8 in the time signature player.

Tap it back: how the timing is judged

After a count-in, you tap the rhythm with a finger, the mouse, Space or any letter key. Each tap is timed against the audio clock that plays the count-in, and compared with the moment each note should start — one expected tap per note, none for a rest or a tied continuation. Taps are matched to notes in order, so one missed or extra tap affects one note, not the rest of the bar.

How close counts as “on time” depends on the tempo: 7.5% of a beat, never tighter than 35 ms or looser than 70 ms; up to twice that is “a little” early or late; further is early or late. A tap can only belong to the note it is nearest — never more than half-way to the next one. The results say which notes were off and how, in words, rather than in milliseconds a browser cannot promise: screens, touch input and especially wireless headphones add delays of their own.

If your results keep showing early or late notes between beats while the notes on the beat are fine, the usual remedy is to say every count, not just the ones you play: slow the tempo down, turn on the beat clicks, and count out loud while you tap.

Knowing note values is not the same as playing them

You can name every note value and still fall apart on a bar that mixes them. The fix is not more theory but a physical habit — count, hear, tap — which is what this tool drills. For the values themselves, start with note values and rests and beat and rhythm.

Covers 2/4, 3/4, 4/4 and 6/8; whole, half, quarter, eighth and sixteenth notes and rests; dotted notes; ties; and syncopation. Triplets and other tuplets are not included yet. Nothing you tap is recorded or saved.