This could be the curve of any loudspeaker because Erik has not told us where the mic is. You can get that kind of bass out of an LS3 5A if you put the mic one foot away from it. The mic is obviously farther away as you can clearly see room nodes in the bass. There is a strong one at 30 Hz which is boosting the bass but 20 Hz is 8 dB down and is down even lower at other parts of the room. I would guess without the node the speaker starts rolling off at 40 Hz. Volume also makes a difference. This is probably a smaller tower or medium sized bookshelf speaker. Something with two 8" woofers or one 10"