Also, and completely tangential to the point, I want to mention that Korean mobile-phone / meeting etiquette is very interesting. You don't leave the room to take a call. Instead, you turn toward the wall, lean over, say "yo bo sae o", and then hold a conversation that is audible to the rest of the room only as a series of quiet murmurs. I think Korean phonemes are somehow optimal for very quiet conversations like this. Maybe because there aren't very many, and they're pretty distinct from each other. I have no science to back that up.