Window treatments

[summo]

Hey guys,

In Australia (and most countries i think), it is the law to have any new room built with a certain sized window for ventilation

So my massive theatre in my new home now has a window which is a real pain in the ***.

My question is, what can i do to sound proof or sound treat this window?

I was thinking of just sticking a blockout curtain to cover it but having a random curtain in the corner of the Theatre isn't all that attractive

Thoughts?