In general, a window causes the fading in and out of the amplitude of the impulse at the beginning and end.
Like the fade-in or fade-out of a piece of music, it prevents an abrupt stop. An abrupt stop can create high-frequency energy in the impulse that is not intended or desirable.
Window type:selects the window function, see Wikipedia article above. Blackman Optimal is standard in Acourate.
Result Curve : stores the result in the specified memory bank.
Orientation symmetric : fades mirror-symmetrically from the absolute center of the pulse file
Orientation right / left of pos : only fades to the left or right of the peak position (peak is determined automatically)
Orientation pos symm : fades mirror-symmetrically from the peak position (peak is determined automatically)
Orientation R window width : fades out to the right of the specified position within the given sample length.
An impulse can be brought smoothly to zero at the end or the beginning or both.
If a pulse does not begin or end with 0, the resulting sharp “corner” in the impulse creates high freqency components in the impulse that are usually not intended or desirable.
After multiple convolutions or in some extreme cases, comb filtering or interference can occur. Then check the endpoints of the impulse, which may be non-zero. Secondary impulses can also appear at the end after such calculations. These can be eliminated by windowing.
If an already windowed pulse is shortened to an extreme, it can possibly be cut off before it has naturally dropped to zero. Windowing gently fades this out.
The Blackman Optimal Window offers a wide, gently tapered window, ideal for long impulses or high-frequency corrections.
The cosine-tapered 50% window offers a short fade in / out which can be useful for the maximum use of particularly short filters (1024 tabs for MiniDSP), or extreme phase correction in the deep bass.