> For the complete documentation index, see [llms.txt](https://cajac.gitbook.io/ctf-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cajac.gitbook.io/ctf-notes/misc/steganography/spectrograms.md).
# Spectrograms
A spectrogram is a visual representation of the [spectrum](https://en.wikipedia.org/wiki/Spectral_density) of [frequencies](https://en.wikipedia.org/wiki/Frequencies) of a signal as it varies with time. When applied to an [audio signal](https://en.wikipedia.org/wiki/Audio_signal), spectrograms are sometimes called sonographs, voiceprints, or voicegrams. When the data are represented in a 3D plot they may be called [*waterfall displays*](https://en.wikipedia.org/wiki/Waterfall_display).
## Audacity
1. Open the audio file with `File` -> `Open...`
2. Select the three dots next to the Up-arrow to the right of the filename
3. Select Spectrogram
Changing view to Spectrogram in Audacity
The Spetrogram view will look something like this
Spectrogram view in Audacity
## Sonic Visualiser
1. Open the audio file with `File` -> `Open...`
2. Select `Layer` and `Add Spectrogram`
3. Zoom in/out with the `Up/Down` arrow keys, or the mouse wheel
4. Move the spectrogram with the `Left`/`Right` arrow keys
