Mystery of the CO2 Balloons!
As expected, they act like a lens, a magnifier of sound. No mystery there. Just as a dense glass refracts light, the denser gas refracts sound.
The mystery is why balloons filled with co2 leak down faster than identical balloons filled by mouth. Yes, there is some co2 in my exhaled breath, but it is mostly n2, and o2. I would hav expected the n2 and o2 to leak out more quickly, being smaller molecules. So whatzup wit dat?