Stop your Mac switching the microphone to your AirPods

Why the microphone moves

macOS has one rule for choosing your audio device: whatever connected most recently wins. There is no notion of preference, and no way to tell it that one device matters more than another.

That rule applies to the microphone as well as the speakers. macOS keeps one default input and one default output, chosen separately, and a pair of AirPods is both at once. When they connect they are the newest device in both lists, so they can take over your microphone as well as your sound.

Why it makes everything sound worse

Bluetooth headphones work in two modes. One is for listening and carries good quality audio. The other is for talking and listening at the same time, and carries much lower quality in both directions. Apple describes this in its own support article on reduced Bluetooth sound quality.

The headphones switch to the second mode whenever an app uses their microphone. So the moment your AirPods become the input on a call, your voice drops to Bluetooth call quality, and anything you are listening to gets quieter and can start to crackle, until nothing is using that microphone any more.

One surprising cause: Apple's own advice includes closing System Settings if it is showing your Sound settings, because that page can hold the headphones in the low-quality mode too.

The quick fix

Open System Settings ▸ Sound, choose the Input tab, and select your Mac's built-in microphone or your USB microphone. Then close System Settings.

With a different microphone doing the talking, your AirPods only have to listen, so they can stay in the good-quality mode. Most meeting apps also have their own microphone setting, and it is worth checking that it says the same thing rather than naming your AirPods.

Making them connect less often

If your AirPods also move between your iPhone and Mac on their own, open System Settings ▸ Bluetooth with the AirPods in your ears, click the info button next to them, and change Connect to This Mac to When Last Connected to This Mac.

That makes them join the Mac less often. It does not give macOS a preference, though. Whenever they do connect, they are still the newest device, and your microphone can still move.

Keeping the microphone where you put it

The lasting fix is a ranked list for inputs, separate from outputs: the microphone you want first, the AirPods lower down. Then an AirPods connection can take over your sound without taking your voice with it.

That is what Tunestack does. Output and input are ranked separately, and whenever a device appears it puts each one back on the highest device on its list. One honest limit: a meeting app that insists on a particular microphone can still take it, because no app can prevent that. Tunestack can notice and switch back if you turn that option on.