The autoplay-muting setting is located in the beta version's permissions bar, which can be accessed from the icons next to the URL (either an 'i' for info or a green padlock), notes 9to5Google. You'll have to do this with each and every website, but it should still block sound when navigating to other pages within the site.
The beta includes other upgrades too, like a stronger pop-up blocker and better protection from malicious prompts that try to automatically redirect users to other websites. It also adds HDR video playback for Windows 10 users in HDR mode, a "Split View" multitasking feature for Chrome OS and other developer tweaks. If you're interested, download the beta here.