Audio [Q] Video calls start fine, then goes very quiet (skype, hangouts)

Trying to skype or hangout with the kids and my parents on their Nexus 7 (from my SGS3), and the sound goes really quiet (eg I can barely hear them). The volume doesn't 'change', infact its still on max, it just seems to drop considerably.

I hang up and call back, loud and clear, then eventually will go again. Seems to last 30 seconds to a couple of mins, but always happens. Def my end, swap to my mrs's N4 and its fine.

Originally thought it was just Hangouts, but Skype does it too. No idea what it could be. Infuriating

I am running Cyanogenmod 10.2.0-i9300 / android 4.3.1

Any ideas? Can't seem to find anyone having the same issues / a relsolution