It *is* designed to reduce intake noise. Its likely intended to smooth out an intake resonance. Because the pathfinder's intake is relatively short, its there to reduce noise, or increase power or both.
I thought that is what it was for, I know manufacturers usually put pipes like this in to help quiet the intake, the thing with this one upon inspecting it is that the pipe does not flow all the way from one end to the other. So what would be the point of it being the length it is when it is not open from one end to the other??