You join a Zoom call. The mic icon in the bottom-left isn't crossed out. Zoom's little indicator next to your name shows a green ripple when you speak. You drop into this site's microphone test in another tab and the level meter dances around exactly as it should. Chat lights up: "we can't hear you". And then: "are you muted?". And then: "try leaving and rejoining".
The mic is working. The OS sees it. The browser sees it. Zoom says it sees it. Something between you and the speakers on the other end is silently dropping your audio. The cause is almost always one of four specific things.
Cause 1 — Zoom is listening to a different mic than you think
Zoom remembers the last microphone you used. If you joined yesterday's call on your laptop's built-in mic, and today you plugged in a USB headset before opening the app, Zoom is still pointing at the built-in mic — which is probably now disabled by the OS in favour of the new headset, or buried inside your closed laptop lid.
The symptom matches exactly: a mic is selected, it just isn't the right one. Zoom's level indicator may or may not register sound, depending on whether the wrong mic is still alive at all.
The fix is in Zoom: open Settings → Audio → Microphone dropdown. Pick the device you actually want to use. If a name doesn't appear, click the dropdown while Zoom is in the call — sometimes the live list differs from the pre-meeting list. The same trap applies to Teams (Settings → Devices), Google Meet (gear icon → Audio), and Slack huddles.
If you frequently swap headsets, pinning the default device in Zoom's settings — or unchecking "Automatically adjust microphone volume" — makes the selection sticky between sessions.
Cause 2 — A Zoom mute that isn't the obvious toggle
The big mute button in the bottom-left is the obvious one. There are at least two less-obvious mutes in Zoom that produce identical symptoms:
- Audio not connected. If you joined and dismissed the "Join with computer audio" prompt — or had the "automatically join audio" preference off — your video is connected but your audio isn't. Look for a "Join Audio" or "Connect Audio" prompt where the mute icon would normally be. Until you click it, no audio goes in or out.
- Host-enforced mute. Some meetings are configured so participants can't unmute themselves; the host has to grant permission or unmute you directly. The visible mute icon may show you trying to unmute, but the host's setting overrides. The fix is to raise your hand or message the host in chat — it's a meeting-policy issue, not a technical one.
A useful diagnostic: if the obvious mute toggle looks fine and audio still isn't going out, mouse over the bottom-left mic icon. The tooltip often reveals the actual state — "Connect Audio", "Unmute (host)", "Mute (you're unmuted)".
Cause 3 — OS-level microphone privacy
Modern operating systems have a separate permission layer for the microphone, independent of the app-level permissions. Zoom can have its mic access enabled inside the app, while the OS-wide toggle silently blocks every app from accessing the hardware.
On Windows 11: Settings → Privacy & security → Microphone. There are two switches here — "Microphone access" (global) and "Let apps access your microphone" — and a per-app list further down. All three have to be on for Zoom to receive audio. The same applies on Windows 10 with slightly different menus.
On macOS: System Settings → Privacy & Security → Microphone. The list shows every app that's requested mic access; the toggle next to Zoom has to be on. After a macOS update or a Zoom re-install, this toggle occasionally resets to off without warning — particularly common after major Ventura and Sonoma updates.
The symptom that gives this away: the mic level meter on this site's microphone test works (because you granted the browser permission separately), but Zoom shows no input even though the device is selected. The fix takes thirty seconds in the OS settings, but is invisible from inside Zoom.
Cause 4 — Browser Zoom vs desktop Zoom
Joining a meeting through the browser instead of the desktop app is a separate code path, with its own permission model. The browser asks for mic access once per origin, the OS sees Chrome or Firefox as the consuming app rather than Zoom, and any failure in the chain has a different fix.
Look at the address bar. Most browsers put a microphone icon there once the page has requested access — click it to confirm the permission is granted and to see which device is selected. If the icon shows a crossed-out mic or asks you to allow again, the page has the permission denied or revoked.
Browser-Zoom is also more sensitive to the OS-level permission gap from Cause 3. The browser has to have OS mic permission, on top of the page having site permission. Either gap silently disables audio input.
If you're stuck in browser Zoom and the call won't wait, the fastest fix is usually to leave the meeting, click the "Open in desktop app" link, and rejoin through the native client. Different permission model, different bugs.
A diagnostic flow
- Run this site's microphone test. If the level meter doesn't move, the problem is at the browser-or-OS layer; Zoom isn't even in the picture yet.
- Open Zoom's own audio test: Settings → Audio → Test Mic. If the meter here doesn't move while it does on this site, Zoom has the wrong device selected.
- Check the OS-level mic permission for Zoom. Windows: Settings → Privacy & security → Microphone. macOS: System Settings → Privacy & Security → Microphone. Zoom has to be enabled.
- Inside the meeting, hover the mic icon and read the tooltip. "Connect audio" and "Host muted you" both produce the same silent-input symptom.
- If you joined via the browser, try the desktop app instead. Different permission stack, often different result.
Practical takeaways
- Test the mic in the browser before opening Zoom. This separates "mic broken" from "Zoom configured wrong" in twenty seconds.
- Pin the correct microphone in Zoom's settings rather than relying on the auto-detection. The setting survives device swaps and meeting rejoins.
- If a host has restricted unmute, raise your hand in chat. No amount of clicking the mute button will fix a permission the host has revoked.
Related reading
The mic-works-in-one-app-not-another guide goes wider than Zoom and covers per-application audio routing on Windows and macOS. The pre-meeting check is the five-minute routine that catches every common audio problem before anyone joins. The microphone test and camera test tools are the two thirty-second checks that confirm the hardware itself is fine before you go hunting through settings menus.