coreaudiod

An app may still be holding an audio stream open, for example a browser tab, a call app, or a paused video that has not released the output. Quitting the app usually lets coreaudiod settle.

Virtual audio devices and third party audio drivers can also keep it active. If the problem started after installing audio software, check that software first.

First check the output device in System Settings, Sound. Restarting the Mac is the simplest fix after that. Quitting coreaudiod in Activity Monitor is a common workaround, since macOS starts it again right away, but sound will cut out briefly and apps playing audio may need to be restarted.

If checking the output device did not help and you do not want to restart the whole Mac, you can restart just the audio service. Sound drops for a moment and apps that were playing audio may need to be reopened.

1. Save any recording or call in progress, and quit apps that are playing or recording audio.
2. Open Activity Monitor and type coreaudiod in the search field.
3. Select coreaudiod, click the Stop button (the X) in the toolbar, and choose Quit. Because it runs as the system user _coreaudiod, you may be asked for an administrator password.
4. macOS starts coreaudiod again right away. Reopen your app and test sound.
5. The Terminal equivalent is sudo killall coreaudiod. It changes the running system, so use it only for this purpose.

Audio drivers from other companies, such as those installed by video call apps, noise cancelling tools, and screen recorders, add virtual audio devices. On recent versions of macOS these drivers run in their own processes, which appear in Activity Monitor with names like Core Audio Driver (Name.driver).

Search for Core Audio Driver in Activity Monitor to see which ones are loaded, and check their % CPU. Open Audio MIDI Setup in Applications, Utilities to see every audio device macOS knows about, including virtual ones.

Drivers of this kind are installed in /Library/Audio/Plug-Ins/HAL. If one is causing trouble and you no longer use the app that installed it, remove it with that app's uninstaller rather than deleting files by hand.

Normal: coreaudiod uses a small amount of CPU while sound plays, a microphone is on, or a call is running, and close to nothing when everything is silent.

Worth looking into: coreaudiod stays busy when no app is using audio, sound crackles or cuts out, or the busy period started right after you installed audio software. To see which app is using the microphone, look for the orange indicator in the menu bar and open Control Center, which names the app.

Crackling and dropouts often come from the device or a driver rather than from coreaudiod itself. Work through these from the least disruptive to the most.

1. Open Apple menu > System Settings > Sound and confirm the right output and input devices are selected.
2. Quit apps you are not using that might hold audio open, such as call apps and browser tabs with media.
3. For Bluetooth headphones, disconnect them and connect them again.
4. Open Audio MIDI Setup and look for virtual devices you do not recognize. Remove the app that added them if you no longer use it.
5. Restart coreaudiod as described above, and if that does not help, restart the Mac.