Thanks Johan - I will investigate the omni speaker at the acoustics centre -- thanks for the tip.
I hadn't thought of trying a speaker on the floor. I tried three different configurations last night i.e. two speakers facing sideways (perpendicular to mic), one speaker facing forward, and one speaker in the corner - and saw some significant differences in room response. I will try the floor suggestion tonight and see how this compares with the others. Oh and I found out that C and D are only calculated when bandwidth = octave is selected.