Sound Lock does what the name says, it essentially allows you to limit the sound output level of your playback, and it does this by detecting the loudness of playback and decreases it to the level you set. This way you no longer have to be frustrated by the loud action scenes or soundtrack going through the roof. To achieve this goal effectively, Sound Lock adjusts the system volume per channel (up to 14 channels), and generates smooth sound output throughout the playback. It actualy turns the volume down for you during the loud scenes and winds it back up after they finish, so you can continue to watch the movie without having to adjust the volume manually.
The controls provided allow you to easily set the sound output limit by draging the bar to the desired level.