As you audio guys know, the sound for my web series is abysmal. The production reality that I have to live with is that I am shooting in an actual concrete and steel bunker. I also do not own the property so cannot drill into the walls. The space that I use is 13'4"X17'2"X9'. What can I do to help the sound that does not attach to the walls or ceiling, won't interfere with camera and light placement too badly, and does not cost a truck load of cash?