Volume Trigger Multiplier?

[Thorozar]

Greetings. I am playing around with adding some custom sounds in a scene and I want to raise the volume above 1 on the HeadAudio, but the slider only goes to 1. I assumed that VolumeTriggerMultiplier was going to do the trick, but the volume is the same. What does this action do exactly, and how can i get the volume above the standard 1 if I want?