Comment 35 for bug 183917

Unfortunately the flash sound issues are not possible to be resolved until Flash 10 is released. Flash 9 currently has a problem that cannot be worked around in libflashsupport, and can't be fixed in flash 9. however, flash 10 beta appears to have this problem fixed. So either obtain and install flash 10 beta, then in stall libflashsupport, or continue using flash 9, and use firefox or other applications one at a time.

Alternatively, you can install libasound2-plugins and run the following command to force flash to go through pulseaudio""asoundconf set-pulseaudio