Waves don't work like that. Otherwise it would be impossible to hear bass through (good) headphones.
The issue is that, because of reflections, waves whose wavelengths are on the same order of magnitude as the distance from the speakers to the wall are getting cancelled out, depending on where you listen from. It is a well-known phenomenon.
(Higher frequencies which are multiples of the missing bass frequencies will also be attenuated, but this is less immediately noticeable.)
For instance, if OP has his speakers located 57cm / 22 inches from the back wall, there is going to be a very deep null at 150Hz, due to the reflection from the back wall. (150Hz is 227cm long.)
If OP is listening in the nearfield, that dip will be obnoxious.
On the other hand, if OP is listening at a distance of two meters, the dip will be LESS obnoxious because there will be dozens of dips and peaks in the response, contributing constructive and destructive interference, simultaneously.
This is one of the reasons that loudspeakers are generally measured under two conditions:
1) very very close. For instance, a woofer can be measured with the microphone less than a centimeter from the cone
2) But the preferred method of getting a full range measurement is to measure the speaker outside, far away from any reflective surfaces.
> there is going to be a very deep null [...] due to the reflection from the back wall
That's exactly what I said.
I read the grandparent to imply that distance from the source was the only factor, that one needs to be a certain distance from a source to hear bass frequencies at all, which I'm sure you'll agree is incorrect, as we both seem to have a correct understanding of the physics involved.
The issue is that, because of reflections, waves whose wavelengths are on the same order of magnitude as the distance from the speakers to the wall are getting cancelled out, depending on where you listen from. It is a well-known phenomenon.
(Higher frequencies which are multiples of the missing bass frequencies will also be attenuated, but this is less immediately noticeable.)