Metronome & Tuner

On the Metronome

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

A brief history

The mechanical metronome as we know it was patented in 1815 by Johann Nepomuk Maelzel, building on earlier work by Dietrich Nikolaus Winkel. Within a few years Beethoven was writing M.M. markings — Mälzels Metronom — over the staves of his symphonies, and an entire vocabulary of measurable tempo entered the score. Today the same idea lives in a sliver of JavaScript: a precise clock, a click, and a steady visual pulse.

What BPM really means

BPM stands for beats per minute. A setting of 60 BPM means one beat every second; 120 BPM means two beats per second — the natural cadence of a brisk walk. The note value that receives the beat is set by the lower number of the time signature: in 4/4 the quarter note is the beat, in 6/8 the dotted quarter (or, for slow practice, the eighth). Setting the right reference note matters; a "6/8 at 80" can mean two very different things depending on whether you count eighths or dotted quarters.

Italian tempo vocabulary

Long before numerical BPM, composers used Italian words to describe the character and pace of a movement. These markings remain useful because they describe feel, not just speed:

How to practise with a metronome

The most common mistake is to begin at performance tempo. Start instead at a speed where the passage is genuinely clean — every note in place, every rhythm honest. Once it sits comfortably, raise the tempo by four to six BPM and repeat. Two short, focused sessions of fifteen minutes a day produce more lasting accuracy than an hour of frustrated approximation.

A second technique: practise subdivisions. Set the click to half the working tempo and place two notes on each click, or use a 6/8 grouping to feel the inner triplet. Subdivision exposes uneven sixteenths and rushed triplets that a single click on each downbeat will hide.

Reading the visual pulse

This metronome lights the first beat of each bar in gold. That downbeat is the harmonic and rhythmic anchor: in 3/4 it carries the waltz, in 4/4 it shapes the phrase. The remaining beats are softer pulses around it. The pendulum swings once per beat, mirroring the wooden Maelzel device. Use the visual when the click feels too clinical, 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 we all agree on

Modern Western music is anchored to A4 = 440 Hz, the so-called concert pitch. It was formalised as an international standard in 1939 and codified by the ISO in 1955, replacing centuries of regional disagreement in which orchestral A could sit anywhere from roughly 415 Hz (Baroque) to above 450 Hz (late-romantic central Europe). Some ensembles still tune to 442 or 443 Hz for a brighter sound; many historical-performance groups stay at 415 or 392 Hz. This tuner uses the global standard of 440.

Cents — the small change of pitch

A cent is one hundredth of an equal-tempered semitone. There are twelve semitones in an octave, so the octave contains exactly 1200 cents. Five cents is the limit of what a trained ear can reliably detect on a sustained note; one cent is inaudible. When the needle on this tuner reads ±5 to ±10 cents you are, for practical musical purposes, in tune. Below five cents you are perfectly in tune. Above twenty cents the note is audibly sour and a casual listener will hear it.

Why all twelve notes do not "fit" perfectly

The piano, the fretted guitar and almost every modern instrument use equal temperament: the octave is divided into twelve mathematically equal steps. This is a compromise. Pure intervals derived from the harmonic series — a just major third, a Pythagorean fifth — are slightly different from their tempered counterparts. Equal temperament smears those small errors evenly across all keys so that every key sounds equally good (and equally imperfect). It is the reason a tuner reading 0 cents on every string still leaves a chord that is a few cents away from acoustic purity. This is normal and a feature of the system, not a defect of your instrument.

How this tuner hears you

When you grant microphone access, a short window of the incoming audio — roughly 4096 samples, about a tenth of a second — is analyzed with the YIN algorithm. 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 the fundamental frequency follows. The result is smoothed with a short rolling median to suppress the wobble of pick attack and string decay, and the closest equal-tempered note is reported with its deviation in cents.

Practical tuning advice

Pluck a single open string firmly but without forcing it. Let the note settle for about half a second before reading — the pitch of a freshly plucked string always sharpens briefly under the attack, then drops as it stabilises. Tune up to the target, never down: if you have overshot, drop well below and approach from underneath. This keeps the wraps of the string taut around the tuning post and helps the instrument stay in tune longer.

For guitar in standard tuning the six open strings are E A D G B e — from the low sixth string (82.41 Hz) up to the high first (329.63 Hz). After every string is at zero cents, play a clean open chord and listen: if anything sounds beating or restless, your saddle intonation or your string age may be the cause, not the tuner.