2. Rhythm: beats and their parts
▶ Open in Aratu to hear and change the examples
Three rules describe every rhythm in a bar.
Rule 1. A space separates beats. A line in 4/4 has four groups. If a bar
has the wrong number of beats, Aratu says so in those words: "bar 2 of
bass has 5 beats, but the meter is 4/4".
Rule 2. Symbols written together share their beat equally.
| Written | In one beat |
|---|---|
c |
a quarter note |
cc |
two eighths |
cccc |
four sixteenths |
ccc |
an eighth-note triplet |
ccccc |
a quintuplet |
Rule 3. _ holds the sound before it for one more part; - is a rest.
| Rhythm in one beat | Written |
|---|---|
| sixteenth, sixteenth, eighth | ccc_ |
| sixteenth, eighth, sixteenth | cc_c |
| eighth, sixteenth, sixteenth | c_cc |
| dotted eighth, sixteenth | c__c, or the shorthand c.c |
| eighth rest, eighth | -c |
A _ on its own is a whole beat held, so c _ is a half note and c _ _ _
a whole note. A _ at the start of a bar ties across the bar line.
Rests follow the same rules: - takes one part, as a note would.
| Rest | Written in 4/4 |
|---|---|
| a whole bar, in any meter | | - | |
| eight bars | | - x8 | |
| half | - - |
| quarter | - as a beat |
| eighth | -c or c- |
| sixteenth | -ccc, c-cc |
| dotted eighth, then a sixteenth | -__c or -.c |
Accents. An upper-case symbol is accented: cC cc accents the "and" of
beat one.
Bar lines. | is a bar line, as in a score. A line can hold several
bars: | cc cc | co cc |. A line with no bar line is one bar.
Groups. Square brackets make a group that shares one part, and spaces
are allowed inside them: c[cc] is an eighth and two sixteenths. The .
shorthand stands for __, so c.c is c__c.
Euclidean rhythms. A symbol followed by two numbers in parentheses
spreads that many hits as evenly as can be over that many steps:
b(3,8) is b- -b -- b-, the tresillo, and b(5,8) is b- bb -b b-, the
cinquillo. Alone in its bar it spreads over the whole bar, in any meter, as
a rest alone does; next to other beats it is one beat, and 2[b(3,8)]
spans two. A third number turns it later by that many steps, as rotate
does: b(3,8,2). Marks count for every hit (S(2,4), c(5,8)?), and it
works on drums, percussion strokes, strums and notes (c2(3,8)).
drums {
bd = b(4,16)
hh = c(5,8,1)
sd = - s - s
}