Audio dying during phone calls consistently
I've been having an odd issue with my GSM Gnex lately (probably past month or two). During a phone call, after a short amount of time (usually within 5 minutes), the outgoing and incoming audio will quickly fade away with some garbling. I can call back and have the audio return, only to die again. I don't make/take many phone calls, so I don't have a lot of data on it. I can't say if it happens on every phone call, but it has happened enough times that I know it's a problem.
This has persisted through various clean installs. I'm not sure, but I think it started with a ROM whose name I can't remember, then in CM 10.1 for a few weeks, and it just happened again tonight, after a clean install of the stock 4.3 JWR66Y image directly from Google last night. Although I did flash the newest UGLL1 radio, as well as SuperSU for rooting.
I'm thinking it's hardware, but I don't know enough to make a decision on it; I've had this phone since last summer.
Sorry for the vagueness and lack of detail. Does anyone have any ideas? Experiences? Things I could test?
Thanks in advance.