What algorithm is used for pitch detection?

The tool uses an autocorrelation algorithm on the raw PCM waveform captured from the microphone via the Web Audio API. Autocorrelation finds the period of a periodic signal, from which the fundamental frequency is derived.

Why does the note reading jump around?

Background noise, harmonics, and polyphonic sounds (multiple notes at once) can confuse the pitch detector. Use it in a quiet environment and play or sing a single, sustained note for the most stable readings.

What is 'cents' deviation?

One semitone is divided into 100 cents. A reading of +15 cents means you are 15 cents sharp (above the target pitch), and -15 cents means 15 cents flat. ±50 cents is exactly halfway to the next semitone.

Does this tool store my audio?

No. All processing happens locally in your browser using the Web Audio API. No audio data is ever sent to a server.

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Pitch Detector

Real-time musical pitch and note detector using your microphone.

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About this tool

The Pitch Detector listens to your microphone and identifies the fundamental frequency of the sound in real time using an autocorrelation algorithm. It displays the detected frequency in Hz, the nearest musical note name (A4 = 440 Hz), and how many cents sharp or flat you are from perfect pitch. A chromatic tuner needle visualization gives instant visual feedback. Works with voice, guitar, piano, wind instruments, and more. Best used in a quiet environment with a single sound source.

How to use

1 Click 'Start' and allow microphone access when prompted.
2 Play or sing a note near your microphone.
3 Read the detected frequency (Hz) and nearest note name.
4 Watch the tuner needle for cents deviation — center means in tune.
5 Click 'Stop' to release the microphone.

About this tool

How to use

Frequently Asked Questions