Surround:Dynamic Range Compression

Standard

This mode has the widest dynamic range (the difference between the quietest and loudest sounds).

Quiet remains quiet, loud remains LOUD (i.e. explosions will "blow your socks off!")

Medium

This mode has a medium difference dynamic range.

Making quiet sounds louder and louder sounds quieter (not as big a difference in sound volume)

Maximum

This is maximum compression

Making quiet sounds louder and louder sounds quieter (not as big a difference in sound volume and "keeps your socks on")