Live microphone pitch analysis
Pitch Detector
Identify the nearest musical note, frequency, octave, cents, confidence, and pitch stability in real time.
Detector controls
Set the tuning reference, sensitivity, and display response.
Recent detected notes
Stored only in this browser tab.
Detected notes will appear here.
Nearest note
Pitch history
Recent note and cents movement.
Pitch Detector
This online pitch detector listens through your microphone and identifies the nearest musical note, octave, detected frequency, and cents deviation in real time. It also shows whether the pitch is sharp, flat, or in tune, along with confidence, stability, signal strength, session range, and a scrolling pitch-history graph.
The plugin processes microphone samples locally through the Web Audio API. An AnalyserNode provides real-time time-domain audio data that browser tools can inspect and visualize.
How to Use the Pitch Detector
- Choose an A4 reference between 420 and 460 Hz.
- Select Low, Medium, or High sensitivity.
- Choose Responsive or Stable smoothing.
- Select Start microphone and grant permission.
- Sing or play one clear, sustained note.
- Read the note, frequency, cents, tuning status, confidence, stability, and signal strength.
- Use Freeze, Copy result, Reset session, or Stop microphone as needed.
For clearer results, use one note at a time in a quiet room. Online microphone tuners commonly become less stable when ambient noise or overlapping sounds are present.
How Pitch Detection Works
The detector reads blocks of 2,048 time-domain microphone samples and calculates their root-mean-square amplitude. RMS is used as a signal gate: input below the selected sensitivity threshold is ignored.
For accepted input, the plugin performs an autocorrelation search. It compares the waveform with delayed copies of itself and finds the strongest repeating period. The delay is converted into a frequency using the browser audio sample rate.
The implemented lag range corresponds to approximately 55–1,200 Hz. Frequencies outside that detector range are not directly accepted, even though the resulting note-number validation covers a wider theoretical note range.
Detection Sensitivity
| Setting | Minimum RMS | Minimum correlation | Practical effect |
|---|---|---|---|
| High | 0.006 | 0.48 | Accepts weaker and less-clear input |
| Medium | 0.010 | 0.56 | Balanced default |
| Low | 0.018 | 0.68 | Requires a stronger, clearer signal |
High sensitivity may help with quiet input but can react more easily to noise. Low sensitivity rejects more weak or uncertain signals.
Sensitivity does not increase microphone quality or guarantee a more accurate note. It changes when the detector accepts a signal as usable.
How Notes and Cents Are Calculated
The detected frequency is converted to a MIDI-style note position using the selected A4 reference:
note position = 69 + 12 × log₂(frequency ÷ A4 reference)
The note position is rounded to select the nearest note name and octave. The target frequency for that note is then calculated from the same A4 setting.
Cents deviation is:
cents = 1200 × log₂(detected frequency ÷ target frequency)
Changing A4 from 440 Hz to another value changes the note and cents interpretation. It does not alter the frequency arriving from the microphone.
In Tune, Sharp, and Flat
| Cents result | Status |
|---|---|
| Below −5 cents | Flat |
| −5 to +5 cents | In tune |
| Above +5 cents | Sharp |
The cents meter displays a visual range from −50 to +50. Values outside that range are still calculated, but the marker remains at the nearest end of the meter.
Other online tuners use their own in-tune windows, so their status may differ even when they detect a similar frequency. For example, Muted’s voice tuner describes a wider in-tune area than this plugin’s ±5-cent rule.
Responsive vs Stable Smoothing
Responsive mode keeps up to six recent note-position estimates and displays their arithmetic mean. It reacts more quickly to changes.
Stable mode keeps up to 16 estimates and uses the median. It is less affected by occasional outlying readings and usually produces a steadier note display.
Pitch stability is evaluated separately:
- Responsive allows a recent spread below 0.30 semitones.
- Stable requires a spread below 0.18 semitones.
- Both require detection confidence of at least 70%.
- At least five recent estimates must be available.
Stable mode is useful when the display flickers between nearby notes. Responsive mode is better for observing faster pitch movement.
How to Read the Results
| Output | Meaning |
|---|---|
| Nearest note | Rounded note name and octave |
| Frequency | Raw detected frequency estimate in Hz |
| Cents | Difference from the nearest note under the selected A4 reference |
| Tuning status | In tune, sharp, or flat using the ±5-cent threshold |
| Confidence | Strength of the autocorrelation match |
| Stability | Consistency of recent note estimates |
| Signal strength | RMS amplitude divided by 0.25 and capped at 100% |
| Session minimum | Lowest rounded note detected during the session |
| Session maximum | Highest rounded note detected during the session |
Confidence is not a guaranteed accuracy percentage. A strong repeating waveform can produce high correlation while still being interpreted at the wrong octave because of harmonics.
Pitch History, Freeze, and Stored Notes
The pitch-history graph adds a point approximately every 100 milliseconds and keeps up to 180 points. It plots the smoothed note position rather than microphone volume or waveform amplitude.
Freeze reading stops visible updates so you can inspect the current result. Microphone analysis continues, and selecting Resume reading returns the display to live detection.
Stable detected notes are added to Recent detected notes. The plugin avoids repeatedly saving the same note unless enough time has passed, and it retains up to eight entries in current-tab sessionStorage.
Reset session clears the current result, graph, smoothing window, and session minimum and maximum. It does not erase stored note history. Clear history removes the stored entries without resetting the active detector.
Tips for Clearer Detection
Hold one steady vowel or instrument note and avoid accompaniment. Keep your microphone distance consistent and reduce wide vibrato when checking a fixed pitch.
Use Stable smoothing when the note jumps rapidly. Try Low sensitivity when background noise triggers false readings, or High sensitivity when a quiet signal is repeatedly rejected.
Octave errors can occur when the detector follows a strong harmonic rather than the fundamental frequency. Consumer microphones and browser audio processing can also affect results, so this tool should be treated as a practical estimate rather than a calibrated professional tuner. Competitor pages often present note, Hz, and cents as their main outputs, while some add voice-type ranges, uploaded files, or instrument-specific modes that this plugin does not provide.
Frequently Asked Questions
What note am I singing?
Start the microphone and hold one clear note. The detector displays the nearest note name and octave based on the detected frequency and selected A4 reference.
What do cents mean?
Cents show how far a pitch is from the nearest equal-tempered note. A positive result is sharp, while a negative result is flat.
What does changing A4 do?
It changes the tuning reference used to calculate note names, target frequencies, and cents. The available range is 420–460 Hz.
Why does the note jump between values?
Noise, vibrato, breathiness, changing pitch, and harmonics can make the estimated period fluctuate. Stable smoothing and a clearer sustained note can reduce display movement.
What does detection confidence mean?
It is the strength of the autocorrelation match used to detect waveform repetition. It is not a guarantee that the displayed note or octave is correct.
What does signal strength measure?
It represents microphone RMS amplitude on the plugin’s internal percentage scale. It is not a decibel measurement.
Can I use this as an instrument tuner?
It can identify sustained single notes from instruments within its detection range. It does not include instrument presets, string targets, alternate tunings, or professional calibration.
Does Freeze stop microphone analysis?
No. Freeze pauses visible result updates while the microphone detector continues running.
Why does it show the wrong octave?
A strong harmonic may be detected instead of the fundamental frequency. Changing microphone position, producing a cleaner tone, or reducing background sound may help.
Does the tool record or upload audio?
No. Microphone data is processed locally in the browser and is not recorded or uploaded.