This is a followup question to Can Inspire Courage be used to inspire a whole army?.
Inspire Courage Reads in part
Inspire Courage (Su): A 1st-level bard can use his performance to inspire courage in his allies (including himself), bolstering them against fear and improving their combat abilities. To be affected, an ally must be able to perceive the bard's performance. An affected ally receives a +1 morale bonus on saving throws against charm and fear effects and a +1 competence bonus on attack and weapon damage rolls[...] Inspire courage is a mind-affecting ability. Inspire courage can use audible or visual components. The bard must choose which component to use when starting his performance.
Just because an ally can hear the bardic music or see the actions of the character, doesn't necessarily mean that s/he is actually paying attention to it.
So, is simply letting the inspiration wash over your allies enough or do they need to be at least partially active participants by trying to hear/see it? What if they're actively trying to ignore the music to concentrate on something else, for instance a spellcaster casting a spell?