Google Chrome adjust volume per tab

You can active one of chromes flags on chrome://flags

Simply enable the called: Tab audio muting UI control. This works for Mac, Windows, Linux, Chrome OS.

Then if you're using an old browser restart Chrome but on newer ones simply right click on the tab and the option to mute the tab should be there.

Reference: http://www.omgchrome.com/how-to-enable-tab-mute-chrome-feature/

You could run Chrome Canary at the same time as Chrome; and then use the Windows volume mixer to turn up or down the volume for either app, independently.

https://www.google.com/intl/en/chrome/browser/canary.html

Unless you break each tab into a separate browser, it is not possible, as windows sound control will just see chrome as one browser, not the multiple tabs within the browser.

This doesn't address your question exactly, but it's as close as I can get. Considering it's been over three years since this was posted and there isn't a better solution, this is probably the best we can do. This is, essentially, an expansion on Rowe's solution.

You can't.

Sorry, but them's the breaks. But what you can do (at least in windows) is individually control the volumes of different running programs. So if instead of visiting different websites on different tabs, you visit them with different applications, you can control the volume by clicking the "speaker" icon on the windows taskbar and then clicking "mixer". For example, visit one website in chrome, and the other in firefox or IE. Rowe suggested installing chrome canary as your second browser, but any browser application will work.

Here's a step-by-step for accessing the mixer in windows 7:

http://www.thewindowsclub.com/the-new-windows-7-volume-mixer-control