Here's a little bit of TGL trivia. The song for the Crystal Corridors (the dark blue/white one) has a little bug in it. When the song loops it doesn't reset the pitch envelope on Square 1, so the instrument is slightly different on the first playthrough than it is on repeats.
On the first play through there is no pitch envelope at all, so it sounds solid/heavy. On subsequent playthroughs it uses a vibrato pitch envelope, which gives it a more fragile/alien sound.
I'm pretty it's unintentional, as the switch to the vibrato pitch envelope happens (intentionally) for a later section of the song. I think they just overlooked it.