I work in an open plan office and find potentially relevant discussions to be the most distracting, so I'm glad that most of these now take place asynchronously over instant messaging. If you've even managed to focus in an airport lounge, or a coffee shop then you know your brain can deal with sounds which are completely irrelevant. Similarly, if it just so happens that people are talking about something directly relevant to your problem, you can join in. The potentially relevant discussions are the most insidious though, because the work of deciding whether they are relevant is sufficient to prevent deep focus.