Cool concept, though not really centered around there being only 1. Could also use escalation.

Very interesting, original idea.

I personally think that there can be more done to the design. It feels like one sound but not really one same sound? One sound within 60 sec is kinda repetitive, I think having the sound moves around, or tries to avoid you in some way, or adding things like boosts? I fully understand the jam limitation, these are just some "what if" ideas. And the way that the pitch was changed was indeed very original in my opinion, using that to signal the vertical axis is a smart and original design decision in my opinion. I really enjoyed that sound only gameplay in general, thanks for the game!