In short
A Mac changes its audio devices during a call for three reasons: AirPods or Beats moving automatically between your Apple devices, a Bluetooth headset dropping and reconnecting, or a new device being plugged in and becoming the default.
You can stop the first with one setting per device, and reduce the other two with habits.
This guide explains each, what it does to the call and to a recording running beside it, and what to change.
AirPods switching between devices
AirPods and recent Beats headphones are signed in to your Apple Account and can move between your iPhone, iPad and Mac on their own. Start playing something on the phone and they may leave the Mac, in the middle of your call.
Turn off automatic switching on the Mac
- Put the AirPods in your ears so they connect to the Mac.
- Open System Settings. Choose your AirPods in the sidebar, or open Bluetooth and click the Info button beside them.
- Find Connect to this Mac and choose When last connected to this Mac instead of Automatically.
With that set, the AirPods connect to the Mac only if the Mac was the last device they were connected to. They stop being pulled over by the Mac, and are less likely to be pulled away from it.
There is a similar setting on the iPhone, in the AirPods' settings under Bluetooth. Set both if the phone keeps taking them.
What it does to the call
When the AirPods leave, macOS moves the output to the next device, usually the built-in speakers, and the input back to the built-in microphone. The call continues. The other people may hear a gap and then your voice through a different microphone. You may now be on speakers without noticing, which puts the other side's voice into your microphone; see fixing echo in call recordings.
A Bluetooth headset drops out
Bluetooth headsets disconnect when the battery runs low, when you walk away from the Mac, or when interference is bad. They then reconnect a few seconds later, sometimes as a different mode.
Many headsets have two modes: one for listening, with good sound quality, and one for calls, which carries the microphone at lower quality in both directions. A reconnection can land in either. If the call suddenly sounds worse, the headset has probably switched to call mode.
To reduce it:
- Charge the headset before long calls.
- Keep the Mac within a few metres and with nothing solid between you.
- Use the headset for listening and the Mac's own microphone for speaking, so a headset reconnect does not also change your input. Recording a call while wearing AirPods or a Bluetooth headset explains the setup.
A new device takes over
Plugging in a display, dock, webcam or USB headset can make it the Mac's default output, input, or both. If it happens mid-call, your voice may suddenly come from a microphone across the desk.
Connect devices before the call, then check System Settings › Sound › Input and Output. Choosing the right microphone on a Mac covers the settings, and why the call app may keep its own choice regardless.
What a device switch does to a recording
A recorder running beside the call has two things to follow: your microphone and the sound the Mac plays.
- Your microphone. If the default input changes, a recorder either follows it, carries on with the old device, or stops. Following is the useful behaviour, but even then there is usually a short gap at the switch while the new device starts.
- What the Mac plays. A recorder that captures the Mac's output before it reaches a device is not affected by which headphones are connected. One that records a particular output device loses the other side when that device goes.
After any call where devices changed, listen to a few points in the recording before relying on it. Meeting recording silent or transcript empty covers what to check if a side went quiet.
How Notey handles a switch
Notey records your side from the Mac's default input and follows it when it changes, including during a recording. The sound your Mac plays is captured with a Core Audio process tap, which does not depend on which headphones or speakers are connected.
Notey watches each side while recording and tells you if one stops arriving: "Notey has stopped hearing your microphone." stays on screen until it comes back. If one side stops arriving for part of the meeting, the meeting is marked incomplete and says why, rather than being presented as whole. Why a recording is marked incomplete explains what the mark means and what is still usable.
Notey also treats the call app briefly letting go of the audio, which happens when you switch headphones, as part of the same call, so the floating button does not report the call as ended and a new one as started.
Frequently asked questions
How do I stop AirPods switching between my iPhone and Mac?
Open your AirPods' settings on the Mac while they are connected and set Connect to this Mac to When last connected to this Mac instead of Automatically. Do the same on the iPhone if you want it to stop taking them from the Mac.
Why does my call audio suddenly come out of the Mac's speakers?
The headphones disconnected or moved to another device, and macOS fell back to the next output, usually the built-in speakers. The call continues on the new device.
Does switching headphones during a call ruin a recording?
It depends on the recorder. A recorder that follows device changes carries on, with a short gap at the moment of the switch. One that is tied to the original device can stop hearing that side until you restart it.