Currently Being ModeratedJun 3, 2011 2:28 PM (in response to elizadoolittle)
Check and see if there's a red light coming from the headphone socket, if so then it's got stuck in digital audio out mode. Try inserting and removing a headphone jack while wiggling it a little to see if you can release the small switch inside the socket (some have had luck with a toothpick but you need to be very careful doing that)
Currently Being ModeratedJun 4, 2011 3:50 AM (in response to iVmichael)
Thanks Michael but there is no light. I do have sound through the headphones though. Any other thoughts?
Currently Being ModeratedJun 4, 2011 3:52 AM (in response to elizadoolittle)
Currently Being ModeratedJul 29, 2011 6:09 PM (in response to elizadoolittle)
I just got back from the Apple Genius Bar, and feel like a fool. The problem was that one of my sound settings was changed. I never thought of checking my settings, because I knew I hadn't changed anything, but it was as simple as that. Somehow "Built-in Input (Aggregated)" had been selected, and it should be set to "Internal Speakers".
I hope it's this simple for you, Eliza!
Currently Being ModeratedAug 6, 2011 6:27 PM (in response to elizadoolittle)
This works, at least until we get a patch from Apple
type the following on terminal (it will ask for your password)
sudo killall coreaudiod
Currently Being ModeratedAug 8, 2011 7:12 PM (in response to Luciano_AR)
The sudo killall coreaudioa seems to work, looking forward to get a patch for this!
Currently Being ModeratedDec 21, 2011 12:06 AM (in response to elizadoolittle)
I posted previuosy but can't edit my old post for some reason., I was having the same problem on my iMac
Previously I stated that in my instance, in the Energy Saver Preferences, I had set the hard drive to sleep whenever possible. I de-selected this option, restarted and have had not had a sound problem for the first time in weeks.
I did experience the problem again where the sound card stops functioning and discovered that the problem is actually caused when the display goes to sleep. In my case, disapbling display sleep is the work-around for this issue.
I reported this as a bug to Apple.
Hope this helps somone else.
Currently Being ModeratedOct 23, 2012 10:57 AM (in response to Luciano_AR)
Hello - I just discovered this problem - no volume control, audio icon greyed out etc.
I used the terminal command you suggested which got sound back up right away (thank you!) but now my headphones won't work. When I plug them in, sound continues to come from the speakers. If anyone has any ideas about that, or what the 'sudo killall coreaudiod' command just did to my computer I would be very grateful!
Currently Being ModeratedFeb 1, 2013 2:47 PM (in response to elizadoolittle)
I tried the pram reset twice but mine still doesn't work. But it starts to work when i turn the bluetooth on.
Currently Being ModeratedJun 16, 2013 10:18 AM (in response to elizadoolittle)
IV Michael, thank you. Your suggestion about the red light in the headphone jack worked for me.
Currently Being ModeratedJan 25, 2014 3:02 PM (in response to Br. Stream)
pretty sure it just kills the coreaudio process. 'sudo' runs the command as root user, because processes like dock and coreaudio cannot be affected by standard admin/user. 'killall' kills the process and usually restarts it, and 'coreaudiod' is the process that does all of the magic that has to do with sound on a mac.