Fixing a MacBook Stuck on Mute

Occasionally, my MacBook Pro will get "stuck on mute"1 if I pull the headphones out too quickly. When you try to increase or decrease the volume, you see this:

When this happens a red LED shines out of the headphone jack:

With some clever Googling, I found out that what is happening here is that the MacBook is stuck on digital optical out (that is, it thinks you have a fiber-optic line -- for high-fidelity output -- stuck in the laptop).

The frustrating thing is that when you open the Mac OS Sound preference pane, it simply confirms that it is stuck and won't let you change it to the normal speakers (called "Internal Speakers"):

The articles linked above explain that this appears to be due to some sort of stuck sensor in the headphone jack and that, most of the time, sticking a toothpick or matchstick in the headphone jack (or blowing with compressed air) can get it to reset itself.

However, I found a way to fix it without blowing or sticking anything in your heaphones jack (something you'll appreciate if you do want to use the thing for optical out!).

Here's what you do:

1. Plug your headphones back in.
2. Play a bit of sound through them (e.g., a song), then stop the sound.
3. Make sure Preferences is quit.
4. Launch Preferences and open the Sound pane.
5. While the Sound pane is open and set to Headphones, pull out the headphone plug from the jack.
6. It will reset itself to "Internal Speakers" and you are good to go.

My theory is that running the Sound preferences pane fresh does some sort of check on the sensors that clears this up. Others noted that you can launch Garage Band and this same check is performed and that can fix it too (but Garage Band is a seriously lame sound editing tool... I uninstalled it in favor of Amadeus Pro a long time ago).

1 (Technically, this isn't "mute" as that is just the volume icon with the indicator all they way greyed out whereas this one has the indicator at full audio but the speaker icon greyed out.)