I run Ubuntu 12.04 classic on 10 laptops at our library and would like to tweak the guest users account to only have sound if headphones are plugged in and muted if no headphones are plugged in. This would eliminate the noise we get in between someone finding their music or video and plugging in headphones.We used to leave the headphones plugged in all the time but they were disappearing too often so now we leave them behind the desk and hence the new issue.