I'm using Ubuntu 14.04. I've just switched from my aging Logitech headset to a nice comfy GameOne Sennheisser which is not using USB (it plugs in to the pink and green audio sockets).
The GameOne headset is excellent but I have one really annoying bizarre problem.
If I use skype it works perfectly.
If I use Clementine to listen to music, it works perfectly.
If I am using Clementine to listen to music and I get a skype call, when I pause Clementine and pick up the call, the caller cannot hear me and I cannot hear them. After a few seconds I can hear them and after a few more, on the rare occasion when they have not hung up in annoyance, they can hear me.
As I use Skype a lot, this means I can no longer listen to music while working :(
I don't know how to even begin investigating this - I've tried google but not seen anyone else with a similar issue.
Clementine eventually proved innocent.
I found that turning off the skype wifi setting in skype's advanced settings does the trick. I've no idea why this works but a patient friend called me repeatedly so I was able to confirm that it was causing the problem.
Ultimately, I suspect all you can do here is 1) report the bug 2) find a work around until the bug is (hopefully) fixed.
First you have to make sure Clementine is definitely where the problem is. There are plenty of other music players to try. If the problem is not specific to Clementine, I would blame Skype.
You could also try upgrading (or downgrading) Skype and Clementine and maybe another version will work.