You look up by bending your neck and your upper back, so when your body is bent forward, looking up will actually move your head (incl your ears) further away from the glass bin.

What the other kind commenters said. I just found it worked. I like the analogy of the funnel, pointing it 90 degrees from where it usually is. OH&S wasn't such a thing back in my day (and I'm not even that old), smoking inside was still a thing (banned in that Australian state I was in a long time ago now). I'd use the air conditioners as a break to get some fresh air.

But anyway, a big bin full of glass being emptied was damn loud, but all the concerts I went to wouldn't have helped.

rather than your ears concentrating/funneling the sound into your ear canal, they would be muffling it since the direct sound wave direction would basically now point into your earlobe