A Zero-average filter adjusts each sample up or down so that the average of all samples becomes zero.

A Normalize filter adjusts each sample to the maximum possible volume without adding distortion. It also zeros popping signals that can occur during the first or last 6 milliseconds.

A Low-pass filter lets low-frequency sounds remain, and tries to eliminate frequencies above a specified frequency. For example, to eliminate high-pitched scratching sounds, use this with the high frequency set to 12000 Hz.

A High-pass filter lets high-frequency sounds remain, and tries to eliminate frequencies below a specified frequency.
If the track has a low-pitched hum, try a high-pass filter with the lowest frequency allowed set to 100.

A Band-pass filter lets sounds between the specified low and high frequencies remain, trying to eliminate frequencies outside this band.

A Band-stop filter tries to eliminate sounds between the specified low and high frequencies.
For example, to use this to eliminate a 60 Hz hum, set the low frequency to 40, the high frequency to 80, and set the Fast/Best slider to Best.

Note that all of these operations cannot be undone, so consider saving a copy of your song before applying them. We will support Edit / Undo for these operations in a future version. We will also be adding a real-time non-destructive EQ in a future version. In the meantime, consider using Anvil Studio with DirectX EQ addins from other manufacturers.