Please point me to the right site if Sound Design is not the correct one.
I have been trying to hide a custom piece of audio within music so that it could not be heard, but will still show up when having a spectrogram run. I did my original testing on a Beatles track, but I threw together a quick siren so I can upload the audio here. *(1)
What I have tried to do with my track is I put in the music on tracks 1 and 2 and then I put the hidden audio on track 3. As for track 4, I put the inverse of track 3 which was created by the Inverse function from Audacity.
This works in Audacity itself and when playing on my Nexus 5's singular speaker. It does not work outside of that software or wearing any kind of earbud or headphones (that I have tested).
My goal is to make this work well enough to the point where I can include the music in a video game and eventually sell the DLC without negatively effecting the quality of experiencing the tracks.
I have been thinking of how it might be possible to make a song around the image sound, but since it looks like spectrograms are produced with frequencies and not amplitude (at least according to this image produced by Sox), so I don't know if it is possible outside of having a separate track.
- (1) I will still have to see about uploading the track or the Audacity project if it is necessary to answer the question.
Edit: To ask Tetsujin to confirm this is what he means by mixing the track to mono, I am putting this picture of my Audacity project. I am still having the issues with the sound though (nothing has changed).