It's been so quiet at work this week

Although I am the only librarian in the library, there is another person who is my cubicle-mate who oversees an outcomes programme, and a research director in what used to be my storage closet. This week, the cubicle-mate is away visiting relatives for a wedding, and the other person worked Monday and Tuesday, but is off the rest of the week, so needless to say, with the exception of an occasional printout (the library has the two main copiers, a heavy-duty black-and-white one, and a colour one). It's been quiet enough that instead of listening to music while I do the data entry job on my earphones, I've been listening (softly) via the speakers. But, when that happens, and someone calls me, the music cuts out as its supposed to for the call, but there's crackling and popping on the other end and the person can't hear me unless I hold the phone directly in front of my face and speak into the microphone, if that. I recently had an update to my phone via my carrier. Granted, the reception is not always great in the hospital, but I have better luck than most because I have windows. It hasn't happened before. It doesn't seem to be an issue when I'm elsewhere, but I haven't been listening to music anywhere else, either. I have a Samsung Galaxy S5 with Android 4.2.2, with the latest firmware T-Mobile is providing. Any ideas? I did look through the settings and there was noise-cancellation feature (like if there's a siren or something in the background) that I turned off, thinking that the copiers or some other background noise could be working with that to cause the problem. But I doubt it. I don't think they've been printing at that point, and if anything, it's been quieter in the library this week than normal. So, I'm thinking it may have been the update, which was supposed to bring greater stability to the system, and I'm not sure, audio may have been affected. I searched for anything like this problem, and I haven't found anything as of yet. The latest update was yesterday; there was another a couple of weeks ago, I think. What I really wish is that they would go ahead and upgrade me to Android 4.4.4, or at least 4.4.3!