Heron comes with all sorts of newfangled stuff including PulseAudio support. This is very nice, but there’s something that not everyone seems to be aware of — PulseAudio and Flash 9 don’t work together by default. You’ll have to install libflashsupport to get audio working in Flash:
sudo apt-get install libflashsupportBest part of all this? Flash audio mixes in perfectly with any other audio without the usual hickups :)