SW is kind of fun to play with, isn't it? :>

If you right click on the chart, you can change the frequency range of the chart. If you only showed above say 50hz or 100hz, that would allow you to see an expanded version of what you have above. SW will also usually fill in more grid lines when you do this, so you would have 100, 200, 300, 400hz, etc. showing up. Also, you can make a new chart and add in frequency responses you measured in order to directly compare your measurements. Alternatively, you can add in a measured response right on top of another one (right click on the chart and select 'add').

If you kept all the volume controls at the same settings (windows volume, amp volume, RS meter setting, line-in vol, SW vol) for all your outdoor measurements and kept your mic, etc. in the same place, then your results actually show that the throat gaps are reducing the sensitivity at the low frequencies, hence making the response flatter compared to the measurement with no gap. Further, if all volumes were the same, the rear chamber looks like it increases the sensitivity in the highs a bit while reducing the lows a bit (or at least damping the peak). Actually, it may just be that it's reducing the cancellations you get from the open back driver and/or the throat gap.

John