By comparing the frequency of the produced sound to what it is actually supposed to be, the sound pattern is corrected with trackers. Using an already-made mod file, the trackers tell the user the frequency of the produced sound and what the note is intended to be. Finding the difference between those two, the tracker recliberates the pattern to produce the ideal sound quality. Graph of the orchestra A with the frequency of 440 Hz. The ideal note should produce a smooth graph as the one shown above.
Sounds produced by the computer however usually deviates from it.