Periodically review and summarize. Listen between the lines. Catalog the content by key words. Attach a key word to each idea and try to build an outline of the whole communication. This won't only help us listen better, it will also help us remember better.
External distractions are such things as traffic noise or people whispering elsewhere in the room.
Physically stop the noise if possible. It's hard not to concentrate if you're taking notes. Assume an attentive posture. Hold eye contact. When these activities fail to run on a reasonable schedule, maybe because discussions are simply more active than we expected or, worse, too much time is taken up by folks who try to interrupt or dominate our time, our concentration can break and interfere with our listening.