My macbook pro running Snow Leopard stopped making sounds a couple hours ago. I've found other reports of people with sounds working through headphones, but that's not the problem I'm seeing. I get no sound when my headphones are plugged in either.

I'm wondering if there's a LaunchAgent or LaunchDaemon to restart which would remedy this. I've already tried killing the coreaudio daemon (and it dutifully automatically restarted) but that didn't fix it.

I need to reboot for an OS update, so I think that'll probably rectify things.

Is there another way?

  • I'm fairly new here but can ask a question that might help. Have you have recently updated to 10.6.8? Many users are reporting audio issues as well as problems with networking and printing after updating to 10.6.8. You may need Apple to issue a patch or you could try some of the interim solutions people are suggesting for these 10.6.8 issues.
    – bg2011
    Jul 1 '11 at 22:54
  • When this happened, I was on 10.6.7. After I restarted, I'm now on 10.6.8. Jul 2 '11 at 12:34
  • Sound came back after a reboot. Jul 2 '11 at 12:34
  • @Doug I wonder if there was an update that installed after you rebooted....
    – daviesgeek
    Dec 29 '11 at 23:22
  • No, just rebooted without any system updates Dec 30 '11 at 15:40

You can kill the CoreAudio process by opening Terminal and running sudo kill -9 `ps ax|grep 'coreaudio[a-z]' | awk '{print $1}'`. It will restart automatically after a couple seconds.

That fixes some problems my aging MBP has been having, where it sometimes fails to detect headphones or decides the speakers aren't connected. No guarantees it will work for every audio problem, but it's worth a shot.

Source: zakgreant on macosxhints forums.

  • 94
    sudo pkill coreaudiod
    – berto
    Mar 7 '16 at 18:12
  • 2
    Worked for me on High Sierra (10.13.2). Feb 12 '18 at 19:04
  • 1
    Worked for me on High Sierra (10.13.6). And I wonder why this problem prevails even after it is 7 years now from the question has been firstly asked..
    – Ramvignesh
    Apr 26 '19 at 9:10
  • 1
    Worked and unfortunately still necessary for Mojave (10.14.6) Oct 3 '19 at 8:04
  • 1
    This got audio back on MBP15 2015 running Catalina 10.15.* Nov 20 '19 at 11:26

sudo pkill -9 coreaudiod kills the coreaudio process immediately. MacOS will automatically restart the coreaudio daemon, which will fix audio output in most cases.

This works on all MacOS versions.

  • 1
    This answer was already provided. You'll be subject to downvotes until you either delete the answer or add additional, supporting, or new info that hasn't already been provided.
    – fsb
    Aug 16 '19 at 13:14
  • 8
    I scrolled through the main answer list and there were only the more complicated commands. But indeed this answer is somewhere in the comments. It seems stupid to delete it though.
    – Joel'-'
    Aug 20 '19 at 9:36
  • On this site, if you can provide additional info to an existing answer, and you have enough reputation, you can edit that answer to add that info. Your answer here is a good example of that opportunity. You don't have to delete your answer but, as I mentioned, you're risking receiving downvotes because of it.
    – fsb
    Aug 20 '19 at 13:09
  • 1
    2020, and brand new MacBook Pro still having the same issue...
    – ofri cofri
    Jun 25 '20 at 13:38
  • 3
    This should be the accepted answer. No need for awk shenanigans.
    – jottr
    Jul 29 '20 at 17:10
sudo kextunload /System/Library/Extensions/AppleHDA.kext 

sudo kextload /System/Library/Extensions/AppleHDA.kext

These two commands will unload then reload the audio kernel extension.

  • 2
    Nice, worked for me on Mavericks.
    – Bombe
    Feb 28 '14 at 22:08
  • Just crashed my comuter (OSX El Capitan)... I would not recommend it, though I guess it worked after restart :-p Dec 11 '15 at 13:31
  • 3
    This actually worked with me on OSX Sierra (whereas the most popular answer did not)
    – rburhum
    Nov 13 '17 at 19:37
  • 1
    Doesn't work for me on Catalina,fails with "has X instances" message.
    – Kheldar
    Dec 18 '19 at 13:11
  • 1
    Can confirm this worked on Mac OS 10.14.6 (and that this problem still happens with a ~8 month old MacBook Pro in 2020 🙃). First command output Failed to unload com.apple.driver.AppleHDA - (libkern/kext) kext is in use or retained (cannot unload) but it worked anyway
    – Jess
    Jan 27 '20 at 10:05

I am on 10.9.2 and have the same problem. Since there are two answers, I wanted to document my findings:

sudo kextunload /System/Library/Extensions/AppleHDA.kext 
sudo kextload /System/Library/Extensions/AppleHDA.kext

These two commands will unload then reload the audio kernel extension. This post fixes my problem 100% of the time, So please upvote that original post

This solution did not work for me:

sudo kill -9 `ps ax|grep 'coreaudio[a-z]' | awk '{print $1}'`

It shuts down the internal speakers and sends the sound to my 27" monitor but does not bring back the sound to my internal speakers or headset. Perhaps in some cases it works, but hopefully this post might explain when to use one solution vs the other.

  • 1
    Apple High Definition Audio kext? Neat, I would not have figured that acronym without this context. Apr 3 '14 at 7:26
  • IMHO, the 'kill -9 `ps ax|grep 'coreaudio...' should always work without the need for a reboot. The restarted coreaudio daemon may pick an audio device which it finds first (no idea how the audio device is selected in that case), but you can reset to the wanted audio device by 'System Preferences...' -> 'Sound' settings. Also, for a browser session, you might need to select the appropriate audio device as well.
    – huch
    Nov 6 '18 at 7:11

In my experience, a reboot is required to fix this. It's a poor fix since it seems to recover from the failure and not address the root cause. I would like to have, but have not yet discovered if there is another quicker/simpler method to get sound back...


Use killall command with _coreaudiod user as parameter:

echo -e "# CoreaudioD restart\nalias audiorestart=\"sudo killall -u _coreaudiod -SIGKILL\"\n" >> ~/.bashrc
source ~/.bashrc

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