On the intake hose for a 2001 Honda Prelude SH there is this U shaped tube with one closed end (sorry about blurry shot):
(The tiny thing sticking up on the top left isn't a tube it's just a solid structural support piece.)
The part is only identified as "TUBE, SIDE BRANCH". It's also discontinued for some reason:
What does this tube do, exactly?
Some clarification from comments; here is where the throttle / MAP sensor / intake manifold is in relation to this: