You probably don't want noisy videos playing in your browser if you can't work out which tab they're coming from, and you may want to manage your privacy at the tab level. The latest builds of Chrome and Firefox cover both these problems.
The Next Web reports that both Chromium and Canary (the experimental bleeding edge of Chrome builds) are carrying audio tab visualisation features, making it simple to spot which tabs are currently playing audio — or as is so frequently the case, which ones are playing annoying autoplay advertisements so that you can quickly kill them.
Firefox isn't boasting audio killing features, but instead the latest pre-release of Firefox 20 for PC and Android is taking private browsing to the tab level. Where you'd previously have to launch an entirely new browser window in private mode, the new release will allow you to declare specific tabs as private tabs within the same browser window.
If you're exceptionally keen, you could try out the pre-release version of either browser, bearing in mind that they're pre-release for a reason. You might gain audio notification and private tab browsing, but it may cost you in stability terms.