Akai MPC X User Manual page 216

The Silence process replaces the region between the start
point and end point with silence.
The Extract process deletes the regions before the start
point and after the end point and saves it as a new sample
(with a name you enter) in your current project.
Tip: This is useful if you recorded a drum loop and wanted
to remove just a snare drum hit, a kick drum hit, etc. to use
separately in the project.
The Normalize process increases a sample's level to the
highest level possible without distortion. This is essentially
a kind of digital gain optimization, so you do not have to
worry about excessive level settings when working with
samples with a wide range of amplitudes.
The Reverse process reverses the region between the start
point and end point.
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