Jon McLaughlin wrote an answer about Salomon Brigade Helmet on September 17, 2011
I just got tho helmet today and was wondering the same thing. It does not appear that these ear pieces are designed to open up to add speakers. However, they are removable, so there my be the option to add different (audio) ear pieces. I will update if I figure it out.
Otherwise, the helmet is great for the money. Looks awesome in person and seems to fit very comfortably!