Look around with the demo
On the tuner, press Try the demo first. A sample pitch moves the needle, the keys, and the 12-second graph. No permission prompt appears.
GUIDE
Vocal Check guide
You can see how pitch appears on screen from the demo and this page before you allow the microphone.
Updated
Three steps to start
Hold one note
Press Turn on microphone and allow the browser permission. Stay 20–30 cm away and hold “ah” for at least two seconds. One person and one note at a time is the clearest case.
Read the numbers, then measure again
Read the note name, Hz, and cents. Change the target or press Clear and sing the same note again. Use earphones when you play the reference tone so the speaker does not leak into the microphone.
Note name, hertz, and cents
Vocal Check looks for one fundamental frequency. It accepts about 60–1200 Hz, and the keyboard draws C2 through B5. The frequency is named from the reference you choose for A4: 440, 442, or 432 Hz.
| Display | Meaning | How to read it |
|---|---|---|
| Note name | Nearest note | A4 is A in the fourth octave. At a 440 Hz reference, A4 sits at 440 Hz. |
| Hz | Fundamental that was found | A larger number is a higher sound. 440.00 Hz matches A4 at that reference. |
| cents | Distance from the comparison note | 100 cents is one semitone. Near 0 matches the comparison note. + is sharp and − is flat. |
| Needle | Moves only within ±50 cents | The green center is about ±5 cents. Farther away, the needle stays at the end and only the number keeps growing. |
Examples
- A4 · 440.00 Hz · 0 cents. At a 440 Hz reference, this is A4. The needle is centered.
- A4 · about 445 Hz · +20 cents. About one fifth of a semitone sharper than that A4. Sing a little lower.
- 0 cents near C4 in auto detect. This is only the distance from the nearest note. It is not a comparison with a song’s target.
- The target is C4 and the sound is D4. In target mode that is about +200 cents, two semitones sharp. The needle stops at +50, so read the number for the distance.
Within ±5 cents the screen says the pitch is in tune. That is what this microphone and this algorithm saw. It does not replace a tuned piano or a measurement instrument.
The 12-second pitch graph
The graph connects pitch positions from the last 12 seconds. It does not draw the waveform or a recording. When the sound stops, the line stops. Leaving the page or turning the microphone off clears the line.
- A level line means the pitch held still in that stretch.
- A downward slope means the note sagged, which often happens when the breath runs out.
- A fast wobble can be an intended vibrato, or the estimate jumping because of noise or overlapping sounds. Hold one note again to tell them apart.
- No line means no pitch has been locked yet. The screen says it is waiting for a sound, or asks you to hold one note longer.
Clear removes the line and leaves the microphone on. To measure again under different conditions, use one person, one vowel, and a slightly closer microphone.
When the microphone is unavailable
The demo and this guide still open. Until you change the permission, use the demo to see how the needle and graph move.
Permission was denied
The screen says “Microphone permission was denied.” Set the microphone to Allow from the address-bar lock, then press Try again. The same failure happens when the system settings have the browser microphone turned off.
No microphone
“No input microphone was found” means the browser did not see an input device. Check the cable, the selected input, or the Bluetooth connection, then try again. The demo still runs.
The browser is unsupported, or the address is not secure
The microphone does not open on an http address. Open https://vocal-check.still-coding.cc/en/ or localhost. An old browser without Web Audio says it cannot analyze a microphone.
Another app is using the microphone
“The microphone could not be opened” means a call, a recording, or a meeting may be holding it. End that use and try again.
You switch tabs or the screen locks
During a measurement, leaving the tab turns the microphone off and leaves “The microphone turned off when you left.” That is so the input is not kept. When you return, Try again starts a new measurement. A running demo is not stopped when you switch tabs.
Noise, several notes, and microphone quality
The tool assumes one pitch. In the cases below the note name may jump, or you may hear sound while the pitch stays empty.
- A fan, air conditioner, or keyboard noise. If the input bars move and the note stays empty, there is noise without a steady voice. Move the microphone closer and sing again.
- Two people, or a chord. There is no single pitch to follow, so the line wanders. Measure one person and one note.
- The reference tone from a speaker. If the piano sound enters the microphone, it mixes with the voice. Use earphones for the reference.
- A distant or quiet microphone. A laptop microphone across the room makes the frequency wobble. Compare again from 20–30 cm on one vowel.
- Browser audio processing. The app asks to turn off echo cancellation, noise suppression, and automatic gain. If the device rejects that, it connects again with the browser default and says so. The same sound can then read a little differently.
Language
The English button at the top right opens the same screen in the other language. Opening /en/guide/ directly shows English, and opening /guide/ directly shows Korean. The page does not redirect from the browser language or region. If a measurement is running, the tuner tells you the microphone will turn off before it carries the graph and practice settings across.
Screens without ads
The tuner, microphone button, target note, keyboard, graph, help dialog, and permission notice do not carry ads in either language. This guide is a reading page that could be considered for ads later. No ad script or ad slot is included before a publisher account is confirmed.
Where the voice data goes is described in Privacy, in the same scope as the code.