Can anyone tell me whether I can install double glazing AND secondary glazing at the same time - in the shape of a sash timber double-glazed window, together with secondary glazing for the same window? I own a flat opposite a noisy pub and need the most effective sound insulation available. Also, should I hire an acoustic surveyor first to find out whether double + sec glazing will be effective - I've heard that sometimes it isn't as noise CAN seep through house walls & roofs.

I'd really appreciate any advice or comments.

Thanks a lot in advance.