I think the way that it works is that by default sound is muted, but browsers allow onClick event handlers to unmute the tab. So if you have a page that tries

I think the way that it works is that by default sound is muted, but browsers allow onClick event handlers to unmute the tab. So if you have a page that tries to make sound after it has loaded but there has been no user interaction, it will be muted. But as soon as you interact with the page, all bets are off.