For the practice a plain click can't give you: triplets and quintuplets against the beat, eighths swung at the ratio you choose, or two pulses at once — three against two, four against three — each with its own sound.
Swing is measured as the ratio between the long and the short note of each pair of eighths — the definition used by Friberg and Sundström in their study of jazz timing (Music Perception, 2002). 1:1 is straight, 2:1 is the triplet feel (the long note takes two thirds of the beat), 3:1 is a dotted-eighth-and-sixteenth. Their measurements found that soloists swing below 2:1 and drummers above it at medium tempos, so try the range rather than one fixed value. With sixteenths, the ratio applies to each pair of sixteenths instead.
In polyrhythm mode the bar is split evenly two ways at once: pulse A as the high click, pulse B as the low one, both starting together on the downbeat. With 3 against 2, the three clicks fall at 0, ⅓ and ⅔ of the bar and the two at 0 and ½ — they meet only on the downbeat. Start slowly, tap one pulse with each hand, and watch where the dots on the circle line up.
How accurate is the timing?
The clicks are scheduled ahead on the browser's audio clock, not with timers, so they stay
exact even if the page is busy. Each click's position in the bar is computed exactly from
the settings.
What swing ratio should I use?
Start at 2:1, the triplet feel, and move it until it feels right for the style and tempo.
Does this replace the regular metronome?
No — for a plain click with accents, the
Metronome is simpler. This one is for
subdivisions, swing and polyrhythms.