This microphone has an advantage over many others in that it has a button to amplify the microphone signal depending on which device you plug it into (= change the output impedance). So it's not a 'noise reducer' at all, but an amplifier (with a battery to amplify the signal). Some device inputs pick up very weak signals and are designed for this, and others expect much stronger signals. So depending on the impedance (signal level) of the microphone you're plugging in, if you send a signal that's too strong for what your input expects, the sound will saturate (noise), and conversely if you send a signal that's too weak for what your input picks up, your device will have to try to amplify the little signal and will therefore add noise.
So that's a fair comment, depending on what you're plugging the mic into, you can adapt the impedance with the knob (but there's no 'noise reduction' system).