Here is an interesting promo idea for a competition Easter Egg hunt with a difference – but first – here is an example of what I want to talk about: Have a listen to the audio file of the latest ADF (Australian Defence Force)
If you want to run it through your own spectrum analyser – this is what you will come up with:

And it is done by using a very simple paint program and a free piece of software – but it’s not just limited to ads – it has been done with songs too:


And the computer game FEZ also has some images hidden in it’s soundtrack too…


OKAY – so enough teasing – you can do the same thing with some patience and a good clean high contrast or a white text or image on a black background created in a paint program.
Save the file as a 900×300 BMP image – your station logo and a hidden ‘password’ would be a great thing to hide in the audio file for listeners to find!
Next you need a free program called Coagula – you can get that – HERE – it is freeware – the download link is at the top right of the page – but, as always scan for viruses! Coagula is an old program now and hasn’t been updated in a while – but it is “essentially an image synthesizer; it is both an image editor and a sound generator from an image. It can generate rich and complex sounds. It has all the useful tools to draw and to create images. It includes lots of specific tools that cannot be found in other image editor.”
What you then do is use your created image (created in landscape format – use the 900×300 as suggested above) otherwise your image will be a little compressed to one edge.
Next… TURN YOUR SPEAKERS DOWN!
Then run the COAGULA program, add an image – load your image – then go to TOOLS – RENDER OPTIONS – change your pitch range to HIGH = 11,000htz and LOW = 210htz – then press RENDER it will play it, but because your speakers are down you didn’t get blasted by static – right?
Next go to RENDER WITHOUT BLUE (you can experiment and try the other settings – but this is GREAT for a white on black logo or text) again the sound file will play, but this time it will be slightly different. Next SAVE SOUND AS – and change the file name to what you want.
Now go to your sound editor import your ad audio and this new sound file layer it on the DAW and watch where you put it so that the audio file isn’t hidden too much behind the music or the voice over. Check it on your spectrum analyser to make sure they can read it. Then mix it down and play it on-air – or drop the audio file on your website or on your socials for listeners to ‘discover’.
The tutorial below is the simplest one I was able to find to show you step by step how to do it.
I’d love to hear any promos you do with this as it is an idea that’s just crying out to be used!
Catch you next time!