One exception to my rule about not interrupting. If you genuinely didn't hear someone, or you didn't understand what they were saying, or they used a word that you just don't understand, then I think it is fine to say quickly, oh, I apologize. You're excuse me Just a moment, but then find out what it is they were saying. Ask them politely. Don't say you didn't say that clearly. Just say, Excuse me.
I didn't understand what you said there. Now, this happens on the phone a lot. Because people can be on cell phone connection, something drops out. And rather than let the person continue and you're confused, I do think it's appropriate to say, Excuse me, or pardon me, but the last 20 seconds dropped out on the phone. I didn't hear you. Would you mind just restating it?
This is good for several reasons. Number one, it allows you to actually hear What they said so much better chance of understanding it, processing it and remembering it. Number two, you're letting the person know, I really care about what you're saying. I'm listening carefully. I'm not just humoring you and doodling or off playing on Facebook. I'm actually trying to understand you, and I'm paying close attention.
Put those two things together. And it's going to work in your favor every time so don't be afraid to interrupt if it's for the explicit purpose of asking for clarification because you just didn't hear something or you just didn't understand