You can, though it's mostly used to keep out excessive noise and hiss from
the recording process. But yeah, that's how it works.
>Most effects like reverb & delay are also gated, to prevent them from
>sounding too mushy on the recording. I suppose they can be used to process
>samples, is this how Roni Size creates the snapping cut-off effect with the
>double bass on 'Brown paper bag'?
Actually, that's done by truncating (chopping short) the upright bass sample.
Noise gates can also be used to make a DJ mixer "transform" effect. Most
noise gates have "key inputs" which mean any signal that goes in the input
can switch on (or off, depending on how it's set up) the sound going
through the noise gate. It's a mess to deal with, though, since you need
not only a gate but a key input device (like a drum machine) and some cables.
Elson