Just because things couldn't be heard, didn't mean they weren't happening, but eventually Fred and George did come out of the backroom, and Fred clapped his brother on the shoulder as George went to put something on a shelf, and he went to join Roger at the counter.
"First day and it's slow business? Weren't you supposed to be dragging in the crowds and all, big injured Quidditch star? Have you learned your way around the shop yet?" He could guarantee that Roger hadn't, since there were quite a few nooks and crannies that you had to be either him or George to know about, but he figured there were some things he did probably need to show him, too.