I am unable to reproduce this (I'm using chrome), so this is very strange.
Can you give me definite instructions on how to produce it? I'd love to fix this, or at least know what causes it:
The audio sounded ok through headphones, I never tested it out loud so maybe that's the issue!
And yeah, sadly HTML5 audio control is not that great, and the audio gets out of sync randomly. All the party sounds are exactly the same length so in theory there should be no issues. On PC it stayed in sync fine so I never noticed this during testing. I tried to add code to keep it in sync in my latest build but I missed the deadline as I said so sadly if you want the best experience, go to the middle immediately while the audio is in sync!