Metronome & Tuner

On the metronome

A short companion to tempo, metre and the discipline of a steady pulse.

A short history

The mechanical metronome as we know it today was patented in 1815 by Johann Nepomuk Mälzel, building on earlier work by Dietrich Nikolaus Winkel. Within a few years Beethoven was writing M.M. markings — Mälzel’s Metronome — above the staves of his symphonies, and a whole vocabulary of measurable tempi entered the score. Today the same idea lives in a few lines of JavaScript: a precise clock, a click and a steady visual pulse.

What BPM really means

BPM stands for beats per minute. 60 BPM means one beat per second; 120 BPM means two beats per second — the natural pace of a brisk walk. Which note value carries the beat is set by the lower number of the time signature: in 4/4 that is the crotchet, in 6/8 the dotted crotchet (or, when practising slowly, the quaver). Getting that reference right matters: “6/8 at 80” can mean two very different things depending on whether you are counting quavers or dotted crotchets.

The Italian tempo vocabulary

Long before BPM numbers, composers used Italian words to describe the character and pace of a movement. These markings are still useful today because they describe the feeling, not just the speed:

How to practise with the click

The commonest mistake is to head straight for the target tempo. A better approach is to build up in stages: take a passage at a tempo where you play it without mistakes, and only then raise it in small steps. If a mistake comes back, drop down a step. Use the plus and minus buttons for fine adjustment, or set your tempo directly with Tap.

A second technique: practise with subdivisions. Set the subdivision to quavers, triplets or semiquavers, and a quieter pulse sounds between the main beats — one that immediately exposes uneven semiquavers and rushed triplets, which a single click on the downbeat hides.

Reading the visual pulse

This metronome shows every beat as its own dot. Tap a dot and it cycles between accent, normal beat and silent — which lets you build your own patterns of emphasis, such as a heavy downbeat with quieter beats after it, or an accented upbeat. The pendulum swings once per beat, echoing Mälzel’s wooden device. Use the picture when the click feels too cold, and trust your ear when it does not.

On the chromatic tuner

Concert pitch, cents, equal temperament — and how this tuner actually listens.

The pitch everyone agrees on

Modern Western music takes its bearings from A4 = 440 Hz, known as concert pitch. It was agreed as an international standard in 1939 and codified by the ISO in 1955 — after centuries of regional disagreement in which the orchestral A could sit anywhere between about 415 Hz (Baroque) and over 450 Hz (late-Romantic central Europe). Some ensembles still tune to 442 or 443 Hz for a brighter sound; much historically informed performance stays at 415 or 392 Hz. This tuner uses 440 by default — Concert pitch A lets you set any reference between 415 and 466 Hz, and both the display and the reference notes follow immediately.

Cents — the small change of pitch

A cent is one hundredth of an equal-tempered semitone. An octave contains twelve semitones, so exactly 1200 cents. Three to five cents is the limit of what a trained ear reliably hears on a sustained note; a single cent is inaudible. When the needle of this tuner sits between ±5 and ±10 cents, you are in tune for all practical musical purposes. Under five cents you are perfectly in tune. Over twenty cents the note sounds audibly off — even an untrained ear will notice.

Why the twelve notes do not quite “fit”

The piano, the fretted guitar and almost every modern instrument use equal temperament: the octave is divided into twelve mathematically equal steps. That is a compromise. Pure intervals from the harmonic series — a just major third, a Pythagorean fifth — differ slightly from their tempered counterparts. Equal temperament spreads these small errors evenly across all keys, so that every key sounds equally good (and equally imperfect). That is precisely why a chord whose strings all read 0 cents still sits a few cents away from acoustic purity. This is normal and a property of the system — not a fault in your instrument.

How this tuner hears you

When you allow microphone access, a short window of the incoming audio is analysed continuously. The signal is compared with delayed copies of itself; the delay at which it best matches its earlier shape gives the period — and from the period follows the fundamental frequency. A clarity measure discards uncertain readings, and a short rolling median smooths the rest, so the display stays calm even as a string dies away. The nearest equal-tempered note is then shown together with its deviation in cents.

Instrument, preset and reference note

Choose your instrument at the top — Guitar, Bass, Ukulele, Violin, Cello or Chromatic. The preset’s open strings appear below the needle; tapping a string plays its reference note, so you can also tune by ear. Pluck a single open string firmly, but without overdriving it, and let the note settle for about half a second before reading — a freshly plucked string is always briefly sharp at the attack. Tune up to the target note, never down: if you overshoot, go well below the target and approach it again from underneath. That keeps the string windings tight and the instrument holds its tuning longer.