Screen recorder with no audio on macOS

The picture is fine and the recording is silent, or it has the Mac's own sound but no voice. These are two separate switches in iRecord, and each fails on its own.

Cause. Microphone is your voice. System Audio is the sound your Mac is making — app sound, video sound, alerts. Both are rows in the Audio card of the New Recording window, and both are off unless you turn them on. The microphone also needs macOS to have granted iRecord microphone access.

Fix

1. Open the New Recording window and find the Audio card.
2. Turn on Microphone for narration, System Audio for the Mac's own sound, or both.
3. If the row Microphone access needed is showing, press Grant and turn iRecord on in Privacy & Security → Microphone.
4. Speak, and watch the level meter next to the Microphone row. It moves with real input — if it is flat, the wrong input device is selected in the picker beside it.
5. Record.

When recording a connected iPhone or iPad, the System Audio row is labelled iPhone Audio and carries the device's own sound instead of the Mac's.

Audio that was not captured cannot be added afterwards. If narration matters, check the meter before you press Record.