This is super cool work Evelyn! The results sound great - and I must compliment your apt use of EmbeddedService for those SoundCloud players in the cloud notebook.
I played around a bit with recreating the Deep Note sound last month, and our approaches appear to be similar (although your code and presentation is much cleaner!) I like your use of AudioChannelCombine/AudioNormalize to combine the many voices - I had used AudioOverlay instead and struggled with setting the right attenuation factor for AudioAmplify to avoid clipping.
I've included my version here in case you're interested. I also attached an MP3 of the result, since I don't have a SoundCloud account. And here are some cool links about the history and creation of the Deep Note (you may have encountered these already in your research):
Attachments:
