Hi folks, maybe I have some things to add to this discussion, but no permanent fixes yet.
I've had similar problems getting sound from internal speakers on my MacBook Air, OS Mavericks. Upon startup one day, I suddenly had no sound. Here is a list of what happened. It’s weird. Sort of a hodgepodge of the symptoms and fixes I've read about so far.
1. At first, the volume buttons on the keyboard would cause the transparent image with the white blocks and speaker emblem to appear, but this would lag horribly (sometimes up to 10 or 15 seconds after pressing the buttons), and they still weren't making the characteristic mac "pop" that you're used to when you turn the volume up and down.
2. After checking System Preferences/ Sound and toggling the buttons a few more times, the volume icon at the top of the desktop went gray, the "internal speakers" option in the sound preferences pane disappeared and read "no output device found" or something like that, and of course I still had no sound.
3. I tried rebooting, but this changed nothing.
4. I tried plugging headphones in and out a few times, but this changed nothing.
5. I tried repairing permissions in the disk utility, but this changed nothing.
6. I tried playing sound a number of ways including through iTunes, youtube, and Reason, but this did nothing. Interestingly, when I pressed space bar on some .wav files to “preview” them in finder, they would not play. That is, not just no sound, they also did not play in the reel even though I pressed the “play” button.
7. I tried deleting the file Library/Preferences/com.apple.BezelServices.plist, but this did nothing.
8. I tried deleting the files Library/Preferences/Audio/com.apple.audio.DeviceSettings.plist and ./com.apple.audio.SystemSettings.plist, but this did nothing.
9. I tried logging in as a different user, which took me back to the situation described in 1., but still no sound.
10. I tried restarting in safe mode, which seemed to do nothing, but then when I restarted in normal mode everything was fixed!!! I had sound, and “internal speakers” was selected in the Sound preference pane. But this only worked for about 10 minutes, and everything went back to how I described it in 2.
11. I tried a bit of prodding in the headphone jack with a toothpick, but nothing.
12. I tried deleting the file Library/Preferences/com.apple.audio.AudioMIDISetup.plist, and this brought the sound back!!! But as soon as I tried “previewing” .wav files in finder as before, the situation described in 1 came back. Now it’s laggy volume buttons and no sound.
13. Upon rebooting in safe mode and rebooting in normal mode, I’m in situation 2 with the grayed out volume control at the top of the desktop, the circle with the slash through it when the transparent sound thing pops up, “no output devices found” in the sound preference pane, and of course no sound.
14. Tried wiping the PRAM with control + option + p + r at startup, and this worked!!! Sound is back!!! Until… yeah, of course, I tried “previewing” some audio files with space bar in finder and I’m back to situation 1 with the laggy volume buttons and no sound output. This time I tried previewing .m4a files in finder rather than the pesky .wav files I had tried before, just in case there was an issue with file type or the .wav’s were corrupted.
Anyway, I’m at a loss. I think for round 15 I’ll try dancing, chanting, and burning incense, or maybe I'll just order a beer. Unless someone has an idea, I’m headed to the genius bar when I get home.
