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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. – Doug Harris Jul 2 '11 at 12:34
  • Sound came back after a reboot. – Doug Harris 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 – Doug Harris Dec 30 '11 at 15:40
84

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.

  • 1
    Thanks this helped! I just had to kill the core audio service. It restarted after a few seconds. – Moussa Apr 10 '13 at 3:06
  • <3 This also works on Mavericks!! :))) – OZZIE Feb 21 '15 at 9:59
  • 9
    sudo pkill coreaudiod – berto Mar 7 '16 at 18:12
  • Just adding, for future reference, I just rebooted on 10.11.6, after a small update (no version number increase), and there was a lag between events and sounds and between video and sounds. While the line above gave me an error about killing the wrong PID, I used grep on the ps command, got the PID for the coreaudio process, killed it using sudo kill -9 and it worked perfectly. Audio restarted and the lag was gone. – Tango Sep 14 '16 at 2:44
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    Worked for me on High Sierra (10.13.2). – Mike Collins Feb 12 '18 at 19:04
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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 – Carles Estevadeordal Dec 11 '15 at 13:31
  • This crashes my macOS Sierra 10.12.1. I do not recommend using this fix. – ejmin Nov 15 '16 at 13:05
  • Works on my old iMac (Snow Leopard) when it fails to recognize my USB sound card. Previously a reboot was needed to fix this, so neat! – Ákos Feb 25 '17 at 10:08
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    This actually worked with me on OSX Sierra (whereas the most popular answer did not) – rburhum Nov 13 '17 at 19:37
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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. – Jason Salaz 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. – Thomas Kettenbach Nov 6 '18 at 7:11
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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...

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