plans for recording room

Hi guys, i'm plannig to build a 4mX4,5m recording room in my garage witch is (or in fact will be...) 11mX4,5m and 2,4m heigh. as it's not builded yet, all distances can be changed. (sorry if my english is not good but normalement je parle français...) i have no need in soundproofing as the garage is not in the house and the first neighbour lives at 500m... anyone can help me with plans or ideas about wall angles and treatment ???? thanks fred.