If you're operating an intercom in a noisy environment, the best approach for keeping racket out of the intercom is to use noise-cancelling microphones. These mikes internally cancel out the ambient noise around them, and (mostly only) transmit sound that is spoken directly into them.
If you've ever heard a news story, or seen part of a documentary, where someone is talking over the headset in a helicopter, they're using a noise-cancelling mike. Without that, there'd be a hell of a lot of noise from the engine and the blades outside the aircraft.
A good noise-cancelling mike is very effective, and you can buy headsets with them. You can buy aircraft headsets, hearing protector headsets with mikes, and computer gaming headsets with noise-cancelling mikes. Though beware that some computer headsets lie, and do not have actual noise-cancelling mikes. Either they'll merely have a directional mike, which is not the same, and only marginally better than a non-directional mike. Or they're relying on computer software to act as a vox, or try to mathmatically remove background noise. i.e. They achieve their trick inside a computer, not the headset, and they don't do as good a job as a real noise-cancelling mike.
There's three common ways that mikes can be noise-cancelling.
There can be two back-to-back mike capsules wired together, so they electrically cancel out background noise that's common to both capsules.
The mike can have a single capsule, and the front and back of the capsule element are carefully exposed to the outside world, so that it's most sensitive to sounds spoken directly into it, and rejects ambient sound coming into both sides.
The mike can be placed inside a chamber, and there's a labyrinth in the chamber with a couple of openings leading to the outside world, one facing the speaker, the other to pick up the ambient sound, and they'll cancel out acoustically inside the chamber.
As to which will be better, I can only say it'll depend on how well the microphone was made, more than anything else.