The plots below were taken at 2, 3, 4 and 5 meter from a boxed Carver driver Goal was to get an idea what happens in the low frequencies because of floor bounce. The microphone was 1 meter above floor level. These measurements are full in-room responses, 16 k MLS with 4096 point FFT. As such some room echoes are present in this response.
Response in the lows is drastically changing with distance. A second set of plots was taken with the microphone at 1.5 meter above the floor level.
The higher position of the microphone seems to flatten (!) things out a little but the dips in the lows are still floating around in function of the distance to the driver.