My friend down the street just finished his full size gym with a basketball court. Its 45x50x18 and he wants to remove the echoes it has, I told him I would ask for advice on here. The hardwood is just being added today.

I thought maybe hanging 4" thick panels like banners from the ceiling and add thick bass traps in the ceiling corners would help but I suspect a lot more is needed.

What should he do?

My friend down the street just finished his full size gym with a basketball court. Its 45x50x18 and he wants to remove the echoes it has, I told him I would ask for advice on here. The hardwood is just being added today.

I thought maybe hanging 4" thick panels like banners from the ceiling and add thick bass traps in the ceiling corners would help but I suspect a lot more is needed.

What should he do?

Corners in large spaces are not economical to treat, nor do the corners trap the bass and release it at "random" frequencies like a small room does. (it is not random, but when building a room it might as well be random, cause momma always said, "ya never know what you are gonna get", you can TRY to predict, but never get it exactly on). Now the banner I idea I have seen done. I have seen the "banner" idea over an indoor swimming pool, they were probably 4" traps. Now how many you need, and how far apart to put them, ask an expert.

As you suggested, fiberglass acoustic baffles are good in such a space, because there's a lot of room for them to hang from the ceiling:

http://www.perdueacoustics.com/images/Baffle_gym_beige.jpg

2-inch thickness is fine, and I wouldn't bother with corner bass traps. No fixed rules on spacing, but use as many as possible!

Regards,
Terry