Use REW to run test on your room.. REW is very handy, and once you understand the graphs, can tell you virtually all you need to know.. i can give you a formula to use that can give you a reasonably tight ball park figure, and i did it on my studio pre REW testing and the result s match near perfect to what i was expecting from measurements.

first you need to measure the length, width, and height of your room and also the temperature, this is critical.

next we need to do some physics. work out the speed of sound for your room, speed of sound varies with temperature. sound travels at 332.5 Mtrs/sec at 0 degrees C. use this calculation

V= 331.5 =0.6T {V=Velocity(speed) T=temp in C} so.

room temp at 20c will give you (0.6x20)+331.5=343.5m/s

using the next calculations we can work out the fundamental (loudest) frequency for your room. {F=frequency}

F=343.5/(length of room x2) = ??

i.e F=343.5/(4.56x2)= 37.6 0r 38Hz

do the same measurement for the 3 axis of your room then you can create a chart with the frequencies of your room, my room looks like this, L - 4.56m W - 4.56m H - 2.37m

this gives me 38Hz, 38Hz, 73Hz as my fundamental frequencies.

Mode Mode 1 Mode 2 Mode 3 Mode 4

Height 73Hz 146Hz 219Hz 292Hz

Length 38Hz 76Hz 114Hz 152Hz

Width 38Hz 76Hz 114Hz 152Hz

this gives me a rough idea of where i need to treat my room as this is where the standing waves are going to build up, I'll have especial trouble at 38HZ.

room modes are the harmonics of the fundamental. room modes are of less importance as they get higher, (multiples of the harmonics become less important)

its a bit in depth but that's acoustics for you.. hope it helps, if you can follow what I'm saying.