This problem started occurring around 10.9.0, might have been in earlier version too, but it still exist now in 10.9.2. The sound disappear on the mac after you wake it from sleep mode, but it’s not consistent, there can go days without it happening. There doesn’t seem to be a specific time interval it needs to be in sleep mode, it can occurred with and without headphones or other external audio plugged in. A lot of people has this problem and posted several topics about it on Apple’s forum. There isn’t any official fix for this problem, but there is a workaround by resetting the audio. This solution has been extended a bit so you only need to call one command after setting it up. We create a file which reset the audio, add an alias to .bashprofile which will call the file.
1. Open a terminal. Run the following command which will create a file and open it (Note: The ~ character means your home folder e.g /Users/john)
touch ~/resetsound && open ~/resetsound
2. Paste the following which will to the resetting of the audio, by unloading and loading
#!/bin/sh sudo kextunload /System/Library/Extensions/AppleHDA.kext sudo kextload /System/Library/Extensions/AppleHDA.kext sudo killall coreaudiod
3. Save and close the file. Back in the terminal we open up .bash_profile to create the alias, which is a shortcut command
4. Append the following line to the file. It will make the resetsound file runable and then run it
alias rezsound='chmod +x ~/resetsound && ~/resetsound'
5. Save and close the file. Reload the .bash_profile so you can call your new command from anywhere
6. Now you can reset the sound by calling “rezsound” from anywhere in the termimal
When ever the mac comes back from sleep and there is no sound, you can now call rezsound from the terminal and it will reset the sound and it will come back to life.