If you've been browsing the Internet at all over the past couple of months, you've probably come across several Flash advertisements on pages that produce sound.
While this isn't a problem if the sound is muted by default, several of these ads begin playback immediately while also defaulting to max volume. Flash Control, an extension for Google Chrome, blocks these Flash applets from loading until you say it's OK.
Begin by downloading and installing the Flash Control extension.
Navigate to a page with a Flash applet on it. You'll notice it no longer automatically loads. You can load individual applets by left-clicking on them.
Alternatively, you can choose to enable Flash applets by clicking on the Flash Control icon in the navigation pane.
A menu of options will appear from which you can choose to enable Flash until the session closes (that is, until you close this window), just for this page, or you can add the Web site to your whitelist (recommended for sites like YouTube).
Not only does this extension improve user experience by blocking really annoying ads, there are other practical bonuses to it as well. For one, the applets that don't load won't be wasting any of your bandwidth. On top of that, any dangerous Flash vulnerabilities sometimes present in ads won't be exploitable.