Google is experimenting with a new feature that would allow users to silence audio notifications in the Chrome browser tab. Admittedly, Google says that it is experimenting with this new UI feature after users had mistakenly assumed that they could click on the tab to mute alert tones, and that it is not promising that the feature will make it to a stable release of Chrome in the future.
Here is what Google says of the experimental audio mute control UI, which is off by default:
This change consolidates all of the existing media indicator UI into a new MediaIndicatorButton class. When the indicator is transitioned to the audio playing or muting state, the button functionality activates; and, when clicked, will toggle tab-wide audio muting. Otherwise, the view only serves to paint the indicator icon with all mouse/gesture events handled by Tab (its parent View).
To learn more about being able to toggle audio alerts on your Chrome tab, you can visit the Chromium page.
Source: Peter Kasting