How to use this test
Start a source
Start microphone and allow access when prompted. Nothing is recorded or uploaded. Demo signal instead analyses a generated 440 Hz waveform without using the microphone or playing sound.
Use one steady note
Sing or play a comfortable sustained note in a quiet space. The detector works from about 65–1,400 Hz. Speech, chords, noise and attacks may not have one reliable periodic pitch.
Read the note and trace
The nearest note uses A4 = 440 Hz and international note names C through B. Negative cents are below the note; positive cents are above it. The recent trace shows roughly ten seconds. Stop releases the source.
What we check
A YIN-style normalized difference algorithm looks for a repeating waveform period in an analysis window of at least 2,048 audio samples, enlarged at higher sample rates. Quiet frames and frames without a strong periodic match do not produce a note. Pitch is an estimate, not a direct count of a singer’s vocal-fold motion.
The periodicity indicator describes how well the waveform repeats; it is not a probability that the named note is correct. Cents are 1/100 of an equal-tempered semitone. The detector does not silently smooth across missing frames, so unreliable input leaves gaps in the trace.
What this test can’t tell you
This is not a hearing test, voice-health assessment, voice-type classifier or calibrated laboratory frequency meter. Harmonics, microphone processing, room noise and mixed notes can cause octave errors or unstable readings. The demo verifies the digital processing path, not microphone hardware.
Something not working?
Microphone access is denied
Allow microphone access for this site in the browser and operating system, then try again. HTTPS or localhost is required.
No stable note appears
Move nearer, reduce background noise and hold one note. The input may be too quiet, outside the supported range or not strongly periodic.
The note jumps by an octave
An overtone may be stronger than the fundamental. Try a gentler, steadier sound and compare a single instrument note.
The demo works but my microphone does not
The demo bypasses microphone permissions and hardware. Check the selected system input, mute state and browser permissions separately.
Common questions
Is my microphone audio sent anywhere?
No. Analysis happens on this page using Web Audio. There is no recording, upload or account requirement.
What does the 440 Hz demo prove?
It supplies a known internal oscillator to the analyser. A result near A4 checks the detector’s digital path; it does not test microphone access, acoustics or calibration.
Can this identify a chord?
No. It estimates a single periodic pitch. Use one note at a time.
Why does the source stop when I leave the page?
The microphone and audio context are released when the page is hidden or unloaded, so capture does not continue in the background.