Just because something is soft, and therefore might seem absorptive to sound, does not mean it is.
There is no way, without doing some pretty extensive tests, to see at what frequencies the specific carpet you have, will absorb.
And maybe, your particular room does not need absorption at those frequencies.
And finally, deflection may be better (and usually is) behind the speakers, where absorption is usually better on side walls and ceiling.
You are just rolling the dice, with the odds against you, that some random carpet will help in your particular room.
There is no way, without doing some pretty extensive tests, to see at what frequencies the specific carpet you have, will absorb.
And maybe, your particular room does not need absorption at those frequencies.
And finally, deflection may be better (and usually is) behind the speakers, where absorption is usually better on side walls and ceiling.
You are just rolling the dice, with the odds against you, that some random carpet will help in your particular room.