Add Rhythm

You will build a four-note rhythmic phrase — quarter, eighth, eighth, half — and then change the tempo without touching a single note.

Prerequisites: Build a Major Scale.

Time in RMT Compose

Three properties carry the timing:

Property	What it is	Unit
tempo	beats per minute — a BaseNote property	BPM
startTime	when the note begins	seconds
duration	how long it sounds	seconds

Start times and durations are in seconds, but you almost never write seconds. You write beats, and let beat() do the conversion:

beat(base)

beat(base) is one beat at the BaseNote's tempo: 60 seconds divided by the tempo. At the default 100 BPM that is 0.6 seconds. Write durations as multiples of it and they stay musically correct at any tempo.

WARNING

Write the beat as beat(base). Spelling the division out by hand does not work — the parser does not accept 60 / tempo(base), and the failure is silent.

Duration reference

Note	Beats	Expression
Whole	4	beat(base) * 4
Half	2	beat(base) * 2
Quarter	1	beat(base)
Eighth	1/2	beat(base) * (1/2)
Sixteenth	1/4	beat(base) * (1/4)
Dotted quarter	3/2	beat(base) * (3/2)
Double-dotted quarter	7/4	beat(base) * (7/4)
Triplet eighth	1/3	beat(base) * (1/3)

Step 1: Clear the workspace

Click the BaseNote, scroll to DELETE ALL NOTES, click Clean Slate, confirm.

The BaseNote stays at 263 Hz, 100 BPM, 4 beats per measure.

Step 2: The quarter note

1. Click the BaseNote to reopen its widget.
2. In ADD NOTE / SILENCE, the defaults are already what you want:
   • Frequency: base.f
   • Duration: beat(base)
   • Start Time: base.t
3. Click Create.

Note 1: one beat long.

Step 3: Two eighth notes

1. Select Note 1. Position stays on At End.
2. Set Frequency to base.f * (9/8) and Duration to beat(base) * (1/2).
3. Click Create Note.

Note 2 starts where Note 1 ends ([1].t + [1].d, filled in for you) and lasts half a beat.

Now do it again from Note 2:

1. Select Note 2. At End.
2. Frequency: base.f * (5/4). Duration: prefilled as beat(base) * (1/2) — inherited from Note 2, so leave it.
3. Click Create Note.

Step 4: The half note

1. Select Note 3. At End.
2. Frequency: base.f * (3/2). Duration: beat(base) * 2.
3. Click Create Note.

Step 5: Listen

Press Play. You should hear: taa — ti-ti — taaaa.

The four durations add up to 1 + ½ + ½ + 2 = 4 beats — exactly one 4/4 measure. In the workspace, Note 4 is twice as wide as Note 1, and Notes 2 and 3 are half as wide.

TIP

Shift-click Play (or long-press it) to loop the phrase. The play icon's bars shrink into dashes that orbit a figure-8 while the loop runs. Shift-click again to exit.

Step 6: Change the tempo

1. Click the BaseNote.
2. On the tempo row, set the Raw: field to 60.
3. Click Save.

Everything slows down and stays in proportion. You wrote every duration as a multiple of beat(base), and every start time as "when the previous note ends" — so the rhythm is a set of relationships, not a set of timestamps.

Try 160. Then put it back to 100.

Duration without typing

Two faster ways to set a duration.

The icon buttons. Select a note, find the duration row, and click one of the five note-length icons: whole, half, quarter, eighth, sixteenth. The two dot buttons multiply what you picked — . by 3/2, .. by 7/4 — and clicking a selected dot again removes it.

WARNING

The icon buttons write the expression into the Raw: field and reveal the Save button. They do not commit. You still have to click Save.

The widget pre-highlights the icon matching the note's current duration. If the duration is not one of the five (a triplet, say), no icon lights up. That is correct, not a bug.

Dragging. Grab a note's right edge in the workspace — the cursor becomes a horizontal resize arrow — and drag. The duration follows, and the note's expression is rewritten for you in beats. Dragging the note's body moves it in time instead.

Silences are real notes

To put a rest in your phrase, do not fake it with an inaudible frequency. Use a silence.

1. Select the note the rest should follow.

2. In ADD NOTE / SILENCE, switch the kind radio from Note to Silence.

   The Frequency field disappears — that is what a silence is: a note with a start time and a duration and no frequency.

3. Set the Duration to how long the rest should last.

4. Click Create Note.

The silence takes an id and appears in the workspace with a dashed outline. Its widget is titled Silence [N] Variables. Notes can reference its startTime and duration like any other note, so a silence chains a phrase exactly the way a sounding note does.

Exercises

1. Dotted rhythm

Select Note 1. On the duration row, click the quarter icon, then the . dot. The Raw field becomes beat(base) * (3/2). Click Save. Now shorten Note 2 to a sixteenth so the bar still adds up.

2. Triplets

Set three consecutive notes to beat(base) * (1/3). Three notes in the space of one beat. No icon will highlight for these — expected.

3. Syncopation

Give Note 1 a duration of beat(base) * (3/2). Because Notes 2, 3 and 4 are chained with [N].t + [N].d, they all shift later automatically, and the accents land off the beat.

4. Rest on the downbeat

Insert a silence of beat(base) before Note 1's material and watch the whole phrase slide right, still intact.

Chaining, in one line

Every note after the first uses this start time:

[1].t + [1].d

"Start when Note 1 ends." The At End radio writes it for you. It is the single most useful expression in the app — change any duration anywhere in the chain and everything downstream re-flows.

Legacy JavaScript syntax

module.getNoteById(1).getVariable('startTime')
  .add(module.getNoteById(1).getVariable('duration'))

What you learned

• beat(base) converts beats to seconds, so durations survive a tempo change.
• The duration icons and dots write an expression; Save commits it.
• Dragging a note's right edge resizes it; dragging its body moves it.
• Silences are a first-class note kind, created from the same section.

Next

• Working with Measures — measure chains and time signatures
• Note Dependencies — the general rule behind chaining
• Transport Controls — play, stop, loop, playhead tracking