Middle and High School teachers, do you allow your students to listen to music on their personal devices (phones, mp3 players) during class?

We have begun trying it from time to time, and I must say, I really like it. They’re quiet, they’re more focused…

I play music aloud sometimes and they’re stuck with it, but this seems to work well, especially with my 8th graders.

What do you think, teachers of the tumblrverse?