In reply to 6ASTU: Tried it once and also found it distracting, luckily my wall tends to play pretty decent music so there is no need.
There is a bloke who always has his headphones on and consequently never speaks to anyone even tho he is there 2 or 3 times a week, maybe this is the point but it seems a bit odd to me as I enjoy the social banter at the wall, by wearing headphones you are defiantly sending out "don't talk to me" signals.
Also tried headphones while bouldering outside but found that even more distracting.
Love Pretty Lights and Opiuo to boulder to.