Doesn't work on FF 3.0.8 Mac Rated 2 out of 5 stars
Thanks for writing this extension, as it sucks that the Mozilla folks threw away the old popup blocker sound preference. Just now I couldn't figure out why a particular Aetna website wasn't working because it would automatically redirect to another page before I could see the popup block message. Running the site in IE, where I have popup block sounds configured, tipped me off, so I went looking for a Firefox extension, but unfortunately this doesn't work in FF 3 for Mac. After doing the installation-prompted restart, the Add-ons window still showed "This add-on will be installed when Firefox is restarted.". I hit the Cancel button and restarted again, but when FF came back up, the extension was still there! At this point, though, it was reporting that the extension was not compatible with 3.0.8, and there was an Uninstall button, so I used that and restarted yet again (which took awhile each time due to all the windows I have open in my session). After doing that, though, the broken extension was finally gone.
After that I installed Noise 1.1.3 and it's working beautifully (only limitation is that it apparently only supports .wav files).