Do mobile browsers automatically block the autoplay of sound on web pages?

Yes, essentially all modern mobile browsers block autoplay of audio by default. Here are the key rules:

What's Blocked

• Any audio or video with sound that tries to play without user interaction

What's Allowed

• Muted autoplay (very commonly permitted)
• Autoplay triggered by a direct user gesture (tap, click)
• Sites the user has explicitly granted autoplay permission

By Browser

• Chrome (Android): Blocks unless the user has interacted with the page or the site has high "media engagement" from prior visits
• Safari (iOS): Strictest — blocks all autoplay with sound, period. Muted autoplay is fine.
• Firefox (Android): Blocks audio autoplay by default
• Samsung Internet: Follows Chrome's rules roughly

Why This Happens

The underlying reason is that mobile users are often in public or on headphones, and unexpected audio is a particularly bad UX on mobile, plus it can burn data.

The Standard Workaround

The standard workaround for things like game audio or ambient sound is to show a "Tap to start" screen that captures a user gesture, then unlock the audio context from within that handler.