Tune your guitar by matching microphone input to reference pitches using Web Audio frequency analysis.
This tuner listens to your guitar through the browser's microphone and uses Web Audio frequency analysis to find the dominant pitch of whatever you play. It names the closest note in standard tuning - the open strings E2, A2, D3, G3, B3, E4 at concert A4 = 440 Hz - and shows how far the pitch sits from it in cents, the unit that splits a semitone into 100 steps. Pluck one string and let it ring; the readout settles on a note name with a sharp or flat offset. The usual surprise: the microphone hears the whole room, not just the guitar, so noise and other instruments can take over the reading.
A concrete input and expected output from the current implementation.
Input
Pluck the open A string and let it ring; the microphone signal peaks at 111.0 Hz.
Expected output
A, roughly 16 cents sharp of A2 (110.0 Hz): the readout shows the note A with a +16 cent offset toward sharp, so the string needs to come down slightly.
The tuner compares the measured 111.0 Hz against the nearest open-string reference, A2 at 110.00 Hz, and converts the ratio to cents: 1200 x log2(111.0 / 110.0) = 15.7, which rounds to 16 cents above the reference. Positive means sharp.
The tool requests microphone access through the browser's getUserMedia API and routes the live audio through a Web Audio AnalyserNode. It estimates the dominant frequency of the captured signal, so the note reported is the strongest periodic component in the audio at that instant. One clear plucked string reads cleanly; noise, voices, or another instrument compete for the same estimate.
The measured frequency is compared against the equal-tempered scale anchored at A4 = 440 Hz, where adjacent semitones are 2^(1/12) apart, about 6 percent. The tool picks the nearest open-string reference (E2 82.41 Hz, A2 110.00 Hz, D3 146.83 Hz, G3 196.00 Hz, B3 246.94 Hz, E4 329.63 Hz) and shows the offset in cents, 100 per semitone: positive sharp, negative flat, near zero in tune.
No. The analysis runs entirely in the browser: the microphone stream is processed locally with the Web Audio API and nothing is sent over the network. The only gate is the browser's permission prompt, which every page must pass before it can touch the microphone, and that permission is about the mic, not about uploading.
Pitch detection follows the loudest periodic sound it hears. Pluck one string at a time, let it ring, and quiet the room; on thick low strings the tuner may lock onto the second harmonic, which reads an octave above the true pitch. If the display still jumps, the environment is too noisy for a reliable reading.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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