When I have my bluetooth headphones connected to my mac, if an application is using the Input, the quality of output is extremely degraded. Why is this? How can I fix it?

This can be reproduced by going to the input tab of system preferences while listening to music in the background.

Here's video of whats going on in Audio MIDI setup, the Format seems to be degraded to 16kHz.


Kinda of relevant. I found this app and in the description it says something interesting:

Get the best audio quality. macOS will normally use the SCO codec if it think you're going to use the microphone.

Could this be the issue I am having?

I just checked by holidng the option key (suggested by @bmike) on the menu bar icon. The codec does indeed switch from ACC to SCO when the mic is activated.

Also relevant:

https://discussions.apple.com/thread/7814292?answerId=31255072022#31255072022 https://audaciousfox.net/2017/airpods-macos-call-quality-fix

  • I don’t have any degradation with AirPods AirPods Pro and Logitech Bluetooth on several Macs. What Mac and what headphones are you using - I’m sure you’re getting issues, but wondering if it’s relating to your headphone hardware.
    – bmike
    Commented Nov 25, 2019 at 4:04
  • @bmike had issue with AirPods (see vid) and beats. Commented Nov 25, 2019 at 4:10
  • 1
    @bmike are you sure your blutooth headphones are selected for both input and output and both are being used at same time? If so, it must be an issue with my Mac. Commented Nov 25, 2019 at 4:11
  • I use them with MS Teams, FaceTime, WebEx, Zoom, BlueJeans and one other software tool I forget the name of routinely. Some meetings I also play music - most it’s purely for meetings / collaboration. Sorry for not reviewing the vid - I go on text almost always - I’m sure it will help someone get an answer, though. This should be solvable is my hunch.
    – bmike
    Commented Nov 25, 2019 at 4:13
  • @bmike Odd. I have this issue with every app that seeks input from my headphones. Commented Nov 25, 2019 at 4:26

2 Answers 2


I'm just going to say it.. the "fix" of switching to the internal mic is not really a fix. It's a workaround, for a broken experience and promise. Lots of people post this as a fix. It's not. Imagine Apple advertising their headphones like this - "Enjoy bluetooth music and talking with your iPhone, iPad, and MacBook*(quality will be significantly degraded when using bluetooth microphone). That would be a joke, but it's actually what is happening. When people buy bluetooth headphones, they want to listen AND talk with them, not switch to a MacBook internal microphone. To be fair, all of my bluetooth headphones have this issue. You can see in the Audio MIDI app that bluetooth input is set in stone to use a lower quality. I even tried a tutorial I found online where the person said that changing the bluetooth plist file would fix it, but I tried it and no fix. For whatever reason, Apple choose to set the bluetooth input to the lowest possible quality on a MacBook.. but that's not the case for iPad and iPhone. So why is it like this on a MacBook? Apple? We are waiting for you to give us a true "fix".

-Here's a link to the fix that worked for someone, but not for me.. maybe it'll work for you. https://discussions.apple.com/thread/6879939

  • 1
    It's a Bluetooth protocol issue. A2DP, the profile used for high quality audio, doesn't support a microphone channel. To use a microphone you need to switch to HFP, which only supports low quality audio. It's awful, but a protocol issue. I'm honestly surprised that they haven't made their own extension. Hopefully LE Audio will solve this situation.
    – Paul
    Commented Dec 6, 2021 at 12:52

When connecting headsets and using the microphone macOS will switch to using SCO.

SCO is good for calls as it provides lower latency.

But it's also terrible for audio-quality as it has much lower bandwidth!


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