In plain language
If audio autoplays for more than 3 seconds there must be an easy way to pause, stop, or lower it.
Who it affects
Screen-reader users competing with page audio, and people with auditory sensitivity.
How to check
Load each page: if sound starts by itself, look for an obvious, keyboard-usable pause/stop/volume control near the top. Worked example — A food delivery app's restaurant menu: load the page: if an embedded iframe (ad, carousel) starts playing audio and the hosting page offers no way to stop it, it fails.
Common misconception
Muting a video by default feels safe, but the rule is about anything that plays automatically, including background music and unmuted ambient video, not just voice audio. Real example: on a car-rental site's checkout flow, sound starts playing automatically, lasts longer than 3 seconds, and there is no way to turn it off or lower it separately.