Menage à Trois Bingo

I've been working on my next podfic, and it's frustrating. About every three-to-five minutes of the recording (and it's over 2 hours long), there is a few seconds of very intrusive buzzing that causes my words to be lost. I will have to rerecord and edit back in about thirty sentences.

Does anyone have an idea how to prevent this? We had been thinking it was interference, perhaps from my phone receiving messages. But it's so very consistent on timing that that seems less likely.