It is a common problem that has been around for ages, and not related to Mavericks. The switch that detects headsets and digital connections within your headset jack is stuck. Sometimes repeatedly plugging and unplugging the headset can clear it, other times people have used forced air to clean out the port and release the switch (as have some used toothpicks), and yet others have had the switch broken and had to have the jack replaced through Apple. These are some of the fixes and just recommendations on possibilities. I don't recommend or condone sticking something in there that is not the suggested interface (such as using toothpicks and such), and you do so at your own risk, as I or anyone else on here is not responsible for your actions. Once the red light is gone (the red light signifies that it thinks it is transmitting a digital signal through the port) the sound should return as usual (some have gotten it to fix wit a reboot as well).
Good luck and hope this helps.
