Audio Isolation

In this quick tutorial, we will once again use a free audio tool called Audacity (https://www.audacityteam.org/download/), to create a stereo panned audio isolation puzzle. When we isolate audio across stereo channels, we create layered audio that can be taken into software and treated as multiple tracks. This is an excellent technique to hide content in those additional layers. For our tutorial, we are hiding a spectrogram message.

The technique we’re going to use this time is very primitive. It is advised to use this as a foundation tool, and build complexity on top of it.

Simple Audio Isolation in Audacity:

We’re going to be using the same file we used in the Metadata and Histogram tutorials (not required, just using for the sake of simplicity) to generate a new audio file, containing another layer of audio.

Our first step is going to be getting both the “secret” audio, and the Host audio into Audacity.

With both files in audacity, we will now modify the panning, or stereo Left/Right Values, between the tracks.

Take your secret audio, and move it to either the left, or the right, 100%. Take the host audio and move it opposite, 100%. Once you have done this, take the secret audio volume down a bit, and then the host audio up a bit. Seeing as we’re using Audacity for this, you may need to render a few different test audio files, to get the volumes right.

Once you’ve fine tuned your audio, your rendered file should have a distinct, visually noticeable split. It will be readable in spectrograms, but with volume modification, it should sound like regular strange noise in the file. You can increase the volume to accentuate the secret audio’s… strangeness… Or decrease it, and make it less audibly visible. What you choose is really up to you, and your need.

Now, I mentioned at the beginning of this tutorial that this should taken as a foundation step, and not typically used as the final product… Although it could. There are other softwares that allow for significantly more masking ability, and are also free. Reaper, and Cakewalk, are two examples. I may cover more advanced techniques in a later tutorial. But this should be a good step in the right direction.