Audio Spectrogram — See the Frequencies in a Recording, Online Free
See the frequencies in a song or a recording, then download the picture — drawn on your device.
Drop an audio file, or click to browse
MP3, WAV, M4A, OGG, FLAC, and more
Processed locally — your file never leaves this tab
Time range
Processed locally — your file never leaves this tab
A spectrogram shows which frequencies are present as time moves across the picture: speech, bass, and anything drawn into the sound. Drop a file, pick a log or linear axis, and download a PNG. The browser computes the FFT locally — nothing is uploaded.
What people look for in it
- Check where the bass, voice and hiss sit before you EQ a track.
- Find a picture or a word someone hid in the frequencies.
- Export a still of a song for a post, a lesson or a lab note.
How to use the Spectrogram Generator
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Drop your audio
Any MP3, WAV, M4A, OGG or FLAC file. Decoding stays on your device.
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Set the view
Log frequency is the usual music view. Narrow the top frequency, and move the dB floor and ceiling if a hidden picture is too dim or too bright. Limit the time range if you only want a section.
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Download the PNG
Preset sizes download at double resolution. The picture is not audio — you cannot play the PNG back into the song.
Frequency over time, as a PNG
Each column is one moment. Height is frequency, high notes at the top. Brighter color means more energy. Viridis, inferno, and gray are the same data with a different scale. The dB floor and ceiling decide what counts as quiet and loud.
The picture is an FFT of the file, drawn in this tab. It is not audio. You cannot play the PNG back into the song.
How to read a hidden picture
A few tracks draw an image by putting energy on chosen frequencies. This page can show that. It does not create one:
- Keep the log axis for the usual music view. It stretches the low end.
- Raise the dB ceiling if a hidden picture is faint.
- Shorten the time range if you only want one span of the file.
Waveform, and the reverse trick
The waveform generator is loudness over time, the shape for a cover image. This page is which frequencies are there.
To build a WAV so a spectrogram shows your picture or a short line of text, use image to audio, then open that WAV here. Log frequency, ceiling around −20 dB. The shape sits between about 400 Hz and 12 kHz. This page only displays.
Spectrogram Generator FAQ
Is my audio uploaded?
No. The browser decodes the file and runs an FFT on it in this tab. There is no upload. After the page loads you can go offline and it still works.
What do the colors mean?
Each column is one moment. Height is frequency, high notes at the top. Brighter color means more energy. Viridis, inferno and gray are the same data with a different scale. The dB floor and ceiling decide what counts as quiet and loud.
Can I turn the picture back into audio?
No. The PNG is a drawing of levels, not the waveform. To hear the file, keep the original. To put a picture into audio, use Image to Audio, then open that WAV here.
How is this different from the waveform generator?
A waveform is loudness over time — the shape on a music player. A spectrogram is which frequencies are there. Use the waveform page for a cover image. Use this page to inspect or reveal frequencies.
Does it work on a phone?
Yes. The controls stack on a narrow screen and the download stays in reach. It works in current Chrome, Edge, Firefox and Safari, on desktop and mobile. A long file takes a moment because each column is an FFT.
Why do some songs hide a picture?
A few tracks, famously Aphex Twin, draw an image by putting energy on chosen frequencies. Raise the dB ceiling if the picture is faint, and keep the log axis. This page only shows it. It does not create one — that is Image to Audio.
Related tools
Waveform Generator
A waveform picture of your audio — colors, size and a transparent PNG, drawn on your device.
Open Waveform Generator
Image to Audio
Paint a picture or a line of text into a WAV. A spectrogram shows it back.
Bass Booster
A real low-shelf EQ: up to +15 dB below 150 Hz, preview and export — nothing leaves your device.