Metronome

Why the tempo does not drift

The obvious way to build a metronome is a timer that fires every so many milliseconds. It does not work: browser timers are approximate, they are delayed by whatever else the page is doing, and the error accumulates until the click is audibly uneven.

This one schedules each click at an exact time on the audio clock, a fraction of a second before it is due — so the sound is placed by the audio hardware rather than by the browser's timer. The result is a click that stays steady while the page is doing other things.

The dot follows the sound rather than leading it, and it is deliberately small: a screen that flashes on every beat would be a genuine problem at these rates, so this page does not do it.

Using it

1. 1

   Set a tempo with the number, the slider, or by pressing Tap tempo in time with the music — two taps is enough, more makes it steadier.

2. 2

   Choose the beats per bar. The first beat of each bar is higher and slightly louder, so you can hear where the bar starts.

3. 3

   Practice slower than feels right. The oldest advice about metronomes is still the best: if you cannot play it cleanly at the slow tempo, the fast one is not ready.

Honest limits

The click is placed by the audio system, so it is steady — but Bluetooth headphones and speakers add a delay, often a tenth of a second or more. That does not make the tempo wrong, but it does mean the click you hear is behind your own playing, which matters if you are recording. Wired is better for anything where timing counts.

Nothing is stored: the tempo and the bar length reset every visit. For a tone rather than a click, use the Tone Generator; for timing a run rather than pacing one, the Stopwatch.