Room with glass windows as a walls.

I have a similar issue. The solution was to apply Marigo Audio dots to the windows.

These were developed by a PhD at Princeton, and they work! 

Call them, and they will help you decide which dots to use based on the size of the windows, and exactly where on the window to place each dot.

Happy Listening! 

@unreceivedogma 

She has never been interested in my advice.

My is reasonable. She is not shy to ask for my advice in tech questions, audio system, cars etc. recently she asked for good old movies. For music she has own taste, but when some times she listened to my stuff at home or in my car, she is asking me for a names. When advice is coming by my initiative it could be ignored for some time but when she rolled it in her head for a while she returns to it and asks  me like nothing happened, makes it look like it her initiative:)

@toddalin are those black-out drapes custom made or sold as a precut panels? Is color choice available?

there is no evidence that glass performs differently than drywall...except in the lower frequencies. 

the challenge with glass is that you can't really hang art or other things like you can with drywall...so you get bad flutter echo. 

Modern rooms also typically don't have carpet. I'm guessing this is true for your daughters new space....so rugs with carpet pads will help. 

Furnishings can also help. Again modern furniture won't be as helpful as it's typically reflective compared to soft and plushy. Clutter can also be helpful. You don't want a sparce room.

best of luck  

If she can afford to live in an apartment on the 43 floor .God Bless Her.. li