To a point it helps to have non-parrallel walls (and floor / ceilings) because the audio energy gets redirected around the room, hopefully dying out before it hits your ears (or the microphone) again as ringing or echo.
But when a room is really small there is just so much audio energy bouncing around it actually excites the room and dependant on room dimensions certain frequencies will bloom loudly. The best way to handle this is with absorption.
I dont mean those inadequate purple foam things you hang on the wall. Those have only limited sucess on mid to high frequencies. I mean some panels made of 2 to 3 inch compressed fiberglass batts covered in cloth, possibly some 4" set in the corner of the room for bass frequencies.
You'll like the room a lot more.
Tom
