Spectrogram Viewer
See a sound as a picture. Messages drawn into the frequency domain are invisible to the ear but obvious on a spectrogram.
You can also drag a file here. WAV, MP3, OGG, FLAC and M4A all work, and nothing is uploaded — the decoding happens in your browser.
Reading a spectrogram
Time runs left to right and frequency bottom to top, with brightness showing how much energy is present. A steady whistle is a horizontal line; a click is a vertical one; speech and music are messy clouds.
These puzzles work by turning an image into sound: treat the picture as a spectrogram and play it back. The result sounds like screeching static, and nobody listening would guess there's anything in it, but drawn out again here, it says whatever was written. If a cache gives you an audio file that sounds like noise, this is the first thing to try.
If the writing is faint, raise the noise floor until the background turns black. If it is squashed into the bottom of the picture, pull the top frequency down. And if it still will not resolve, send the picture to the Channel & Levels Explorer and press Auto levels.