Decibel Shield
Spectrum analyzer › Pitch detector
Pitch detector: the note and frequency you sing or play
Press Start, allow the microphone, and sing or play one steady note. The detector shows the note name and octave, its frequency in hertz, and how many cents sharp or flat it is against standard tuning, A4 = 440 Hz. It works as a chromatic tuner for any instrument that plays one clear note at a time.
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Press Start and allow the microphone
The pitch is worked out in your browser from the microphone and thrown away frame by frame. Nothing is recorded and nothing is uploaded. It reads one note at a time, from about 40 Hz (the low E string of a bass guitar is 41 Hz) to 2,000 Hz, and shows a note only when the sound is steady enough to trust.
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Tuning notes for common instruments
| Instrument | Strings |
|---|---|
| Guitar (standard) | E2 82.41 Hz · A2 110.00 Hz · D3 146.83 Hz · G3 196.00 Hz · B3 246.94 Hz · E4 329.63 Hz |
| Bass guitar (4-string) | E1 41.20 Hz · A1 55.00 Hz · D2 73.42 Hz · G2 98.00 Hz |
| Ukulele (standard) | G4 392.00 Hz · C4 261.63 Hz · E4 329.63 Hz · A4 440.00 Hz |
| Violin | G3 196.00 Hz · D4 293.66 Hz · A4 440.00 Hz · E5 659.26 Hz |
How the detector works
A steady note repeats the same wave shape many times a second, and the number of repeats per second is its frequency. The detector looks for that repeat in the microphone signal, measures its length to a fraction of a sample, and only shows a reading when the sound is clearly repeating. That is why it goes blank for a chord, a noisy room or the decaying tail of a note: it would rather show nothing than a guess. To see every frequency in a sound at once instead of the main note, use the spectrum analyzer.
Notes, octaves and A4 = 440 Hz
Western music divides each octave, a doubling of frequency, into twelve equal semitones, and each semitone into 100 cents, so each semitone is a frequency ratio of the twelfth root of 2, about 1.0595. The international reference is the A above middle C, A4, at 440 Hz (ISO 16); every other note follows from it, and middle C is C4 at about 261.63 Hz. Not everyone tunes to exactly 440, which is why the reference is adjustable.
Train your ear as well as the instrument
A tuner tells you where a note is; your ear decides whether it sounds right. The pitch test measures how small a difference you can hear, from a semitone down to 4 cents, and checks whether you can name a note with nothing to compare it against.
Is this a chromatic tuner?
Yes. It recognises all twelve notes in every octave rather than only the strings of one instrument, and shows how many cents sharp or flat you are, so it tunes any instrument that plays one clear note at a time.
Can it tune a guitar?
Yes. Play one string at a time and let it ring. Tune until the needle sits in the middle and the reading says in tune, within 5 cents. The table on this page lists the target note and frequency for each string of a guitar, bass, ukulele and violin.
What do cents mean?
A cent is one hundredth of a semitone, the step between two neighbouring notes on a piano. 50 cents sharp is halfway to the next note up. About 5 cents is close to the smallest pitch difference people can hear between two pure tones, which is why the reading says in tune within 5 cents.
Why does it show the wrong octave sometimes?
Some instruments put more energy into a harmonic than into the note itself, so the detector can lock onto the octave above or below. The note name is still right; only the octave number moves. Let the note ring steadily and it settles.
Can I tune to A = 432 Hz?
Yes. Change the A4 reference to 432, or to any value from 415 to 466 Hz, and every note is measured against that instead. The standard reference is 440 Hz.
Does it record me?
No. The pitch is worked out in your browser from the microphone and thrown away frame by frame. Nothing is stored or uploaded.
Sources: ISO 16, the 440 Hz tuning standard; HyperPhysics, equal temperament and cents.