Update Chrome to find out which tab is making all that racket
If you consider yourself a power surfer, then it's probably not uncommon for you to have a dozen or so tabs open at any given time. Provided you have enough system RAM to handle that kind of load, there's nothing inherently wrong with loading up a bunch of tabs, but it sure can be annoying one of them starts playing music or an ad out of the blue. One way to track down the culprit is by reloading each tab one-by-one until the noise cuts out -- BAM, there's your culprit. Or you can run the latest version of Chrome (version 32) and see at a glance which tab is blaring through your speakers.
Starting with Chrome 32, there are three new icons that might appear in your tabs. One is an audio icon to let you know that it's playing audio, and the other two reveal which websites are accessing your webcam or are being cast to your television. You'll find the icon on the right side of the tab next to the X.
In addition to the icon, which is even visible when your tabs are squished, a message will appear when you hover your mouse cursor over a tab that's performing one of the three above mentioned actions. For example, it might say, "This tab is playing audio."
If Chrome hasn't yet updated to the newest release, you can force its hand by hitting up the Preferences button and selecting "About Google Chrome."