hi, i've been researching and researching on the best way to get rid of untreated room sound when recording vocals. i saw this on you tube Build A Portable Vocal Booth - YouTube and got the idea but was thinking of using bonded logic ultratouch denim instead of oc 703 because it's specs are higher. and also making it a three panel instead of two. the thickness i would like to have is 3.5" but this was replied to me on another thread (In all cases if you have less than 4" you use rigid, if you have 8" or more you use fluffy, unless you need rigid for structure.) i don't understand why this rule applies. also would i need another panel behind this three panel semi booth. the dimensions i was thinking of using would be 24.5" x 6'. i am completely new to recording vocals so please excuse me for my lack of knowledge. can someone please help me out because the more research i do on this the more hair i pull out of my head. also because of the place i am living in i can't have anything screwed into the walls. thanks every one.