> I say excuse me when I want to pass through. How good is the audio to convey that intent?

Perhaps a bicycle bell would help?

https://www.youtube.com/watch?v=k7oGk-ozhKI&t=26

That's a "prank" video, but I'm quite serious - it does demonstrate that people will instinctively move out of the way when they hear a bike bell. And towards the end of the video (1:38-1:47), he even uses it successfully on an escalator, and in the aisles of a grocery store - so the effect isn't limited to places where you'd expect to encounter bikes.