Have you tried rebooting your computer and making sure your speakers are turned up? Sometimes the audio driver can crash and stop playing anything. (Not a problem with any particular browser, it could happen any time)
I looked into it a bit deeper: Only C2 made HTML5 audio not works in Chrome. I tried some HTML5 videos and other games witch are not on Scirra Arcade and they all had audio in Chrome. So now I'm a bit confused.
I just reinstalled Chrome, but C2 exported games still don't have any sound.. As far as I can remember it all started when I tested the Space Blaster windows demo. Maybe Awesomium broke the sound. I don't know.