Your browser will ask to use the microphone. The sound is drawn and thrown away. Nothing is recorded or uploaded.
Everything runs in your browser. Sound and files are never uploaded.
About the spectrogram
A spectrogram shows sound as a picture. Time goes from left to right. Pitch (frequency) goes from bottom to top. The colour shows how loud each pitch is at that moment. Bright means loud. Dark means quiet.
This free online spectrogram works in two ways. Use your microphone and the picture scrolls live while you whistle, talk or play an instrument. Or open an audio file and see the whole sound at once, with a playhead you can move.
It is also a simple audio spectrum analyzer. It tells you the loudest frequency in Hz and the musical note that goes with it. Move the pointer over the picture to read the frequency at any spot. Nothing is uploaded. Your sound stays on your device.
Features
- Live microphone — a picture that scrolls while you make sound. Browser voice processing is switched off, so the picture is honest.
- Audio and video files — drop an MP3, WAV, OGG, M4A, FLAC or a video with sound.
- Loudest frequency — shown in Hz, with the note name and how many cents away from it.
- Pointer readout — a crosshair tells you the frequency, the note and the time under the pointer.
- Play and seek — play a file and click the picture to jump to any moment.
- Your own settings — FFT size, linear or log pitch scale, highest frequency, four colour maps, speed and zoom.
- PNG download — the picture with axes and a colour legend, ready in one click.
How to use it
- Choose Microphone or Audio file at the top.
- For the microphone, press Start the microphone and allow access.
- Make a sound. Whistle, hum, talk or play a song near the mic.
- For a file, click the box or drop a file on it. Wait a moment while the picture is made.
- Press Play and click the picture to move the playhead.
- Change the colours, highest frequency or FFT size until the picture is clear.
- Press Download PNG to save the picture.
How to read a spectrogram
| You see | It means |
|---|---|
| A flat bright line | One steady tone, like a whistle or a beep |
| Many lines stacked up | A note with overtones, like a voice or a guitar |
| A line going up | A pitch that rises, like a siren or a bird chirp |
| A bright vertical stripe | A short click or a clap |
| A cloud of colour | Noise, like wind or a hiss |
Voices show bands of energy. These are the formants that make the vowels "a", "e" and "o" sound different. Low pitches are near the bottom of the picture and high pitches are near the top.
Check MP3 quality with a spectrogram
A real high-quality file has sound up to about 20 kHz. A low bitrate MP3 cuts the top away. If a "320 kbps" file stops at 16 kHz and is black above that, it was probably made from a lower quality source.
Open the file here and look at the top of the picture. Set Highest frequency to 20 kHz. The tool also shows Highest frequency with sound. This is a rough guide, not a lab test. Some music has no high sound at all, so compare more than one song.
FFT size
| FFT size | What you get |
|---|---|
| 1024 | Sharp in time, blurry in pitch. Good for clicks. |
| 2048 | A good middle. Fine for most sounds. |
| 4096 | Clearer pitch. Good for voice and music. |
| 8192 | Very fine pitch, but blurry in time. Good for steady tones. |
Frequently asked questions
What is a spectrogram?
It is a picture of sound. It shows which pitches are in a sound and how loud they are, as time goes by.
How do I find the frequency of a whistle or hum?
Press Start, then whistle. The Loudest frequency box shows the pitch in Hz and the closest note. A steady whistle is a clear bright line.
Why is the loudest frequency sometimes wrong?
A voice or an instrument has overtones. The loudest one is not always the pitch you hear. Background noise can also win. Use a quiet room and a steady tone for the best result.
Can I use a video file?
Yes, if your browser can read the sound track. MP4 and WebM usually work. If a file fails, convert it to MP3 or WAV first.
Is my sound uploaded?
No. The microphone and the files are used only in your browser. Nothing is sent to a server.
Why is the microphone picture empty?
The browser may have blocked the microphone. Allow it in the address bar. Also check that no other app is using it.
Good to know
- A spectrogram shows sound. It does not give medical or health advice.
- The level in dB is relative to a full-scale signal. 0 dB is the loudest possible, so normal sound is below zero.
- Colour map and level changes affect new live sound only. The old part of the live picture keeps its colours.
- Changing the pitch scale or highest frequency clears the live picture.
- A very long file is sampled to keep the page fast. The picture is still correct, but short clicks may be missed.
Related tools
- Noise Meter — see how loud a room is
- Tone Generator — make a tone to test your speakers
- Guitar Tuner — tune a string by ear and eye
- Mic Test — check that your microphone works
- Audio Trim — cut the part you want from a sound file
