Firefox set to silence auto-play audio with Version 66

Mozilla this week announced that the next upgrade to Firefox, due for release March 19, will automatically block all auto-play audio by default.
Only when the user explicitly interacts with the website to launch audio or video content – Pearce cited clicking a “Play” button as an example – will Firefox allow sound to stream.
Auto-play blocking will be enabled by default in Firefox 66, currently scheduled for release March 19.
Users may set site-specific controls to allow some destinations to start playing audio as soon as the browser pulls up a page. And auto-play video will be allowed when muted, Pearce said. He recommended that site developers adopt the latter practice, perhaps with an “Unmute” button for users to click. “Note that muted auto-play is also currently allowed by default in all major browsers which block auto-play media,” Pearce said.
On personal computers, Google tracks user behavior and “if the user has frequently played media on the site, according to the Media Engagement Index” (MEI), audio will pour from the speakers. The MEI, according to a Google explanatory document, “provide[s] a metric reflecting the engagement of a given user with regards to media playback on a given origin.” Sites with high MEI scores – a prime example would be youtube.com – are given a pass on the no-sound rule.
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Chrome also already blocks auto-played Web Audio content, something Pearce said Firefox would only get to sometime later this year. The Web Audio API (application programming interface) is a newer make-sound standard for web applications.