After you have selected a target with DIMFIC, the signal might be a little noisy. When you are outside, there might be cars, people, wind, or other noises. These distractions can will make it harder to hear the birdcalls. DIMFIC can remove these distractions.
The second stage of DIMFIC is the "Filtering Stage". To be useful in the field, DIMFIC removes ambient and extraneous noise. Computer simulations run by Loftingware have shown that removing the frequencies below 5kHz removes most of the noise while leaving the birdcalls intact.
These two pictures show how the filters remove the extra noise.
The pictures are sort of like the graphic equalizer on your stereo,
but more detailed.