Abbreviation for Radio Frequency Interference. RFI is a specific type of EMI relating only to signals produced by radio and television systems. These hi frequency RF signals can find their way into our audio equipment where they can produce hums, buzzes, and occasionally even reproduce the actual audio of the radio station through the equipment. Most audio circuits are not designed to deal with RF frequencies, which is what turns them into problems, so the normal course of action is usually to prevent them from entering in the first place. This is typically accomplished by shielding, filtering, and proper grounding among other things.