This checks two different things: microphone permission (if your site records audio) and autoplay-with-sound policy (if your site plays audio/video automatically). They are unrelated browser mechanisms.
Note: your browser's per-site "Sound: Allow / Block / Ask" setting (visible in the site info panel) is not exposed to JavaScript at all — not via the Permissions API, not via any other API. Chromium deliberately hides it from pages. The only thing a page can ever observe is whether audio actually plays, via the test below.