In System Settings > Sound > Input, select the microphone you want. Test that same input in a short QuickTime Player recording. If you can hear your voice there, check microphone access and the selected input in the app where you went quiet.
01Choose the microphone by name
Section linkOpen the Apple menu and choose System Settings > Sound > Input. Pick the built-in microphone or the external device you intend to use. A connected display or headset can add another input. Speak at your normal volume and adjust Input volume if that control is available and the signal is too quiet.
02Make a short recording
Section linkIn QuickTime Player, choose File > New Audio Recording. Use the menu beside the record button to select the same microphone if several are available. Record a sentence, stop, and play it back using a speaker or headphones you know work. If a USB microphone gives you silence, repeat the test with the built-in microphone if your Mac has one.
03If only one app goes quiet
Section linkQuit the affected app. Open System Settings > Privacy & Security > Microphone, allow access for that app, then reopen it. Check the input and mute controls inside the app too. Run its test or record another short sample before joining a call. For a web meeting, also check whether the site has microphone access in your browser.
04If the external input is missing
Section linkReconnect the microphone or audio interface and check Sound > Input again. If the internal microphone records clearly but the external device still fails, focus on the external connection and check the maker’s macOS compatibility and software guidance. If neither input records in QuickTime, recheck the selected device and permissions before using Apple Support to investigate.