Where is the audio low pass rolloff curve GUI? (Unity 3)

According to (local docs): file:///E:/Program%20Files%20(x86)/Unity3/Editor/Data/Documentation/Documentation/Components/class-AudioLowPassFilter.html

There is supposed to be some curve editor GUI for setting the rolloff curve that controls the low-pass frequency based on distance from audio source.

However, I've looked everywhere I think, and I don't see such an interface with such a curve, even though I add the Audio Low Pass Filter component. Do I need to add some sort of new curve component, or is the documentation just erratic?

I really like this feature as it makes for realistic sound effects in large environments, so I'd love to get it running.

It's in the Audio Source Component, under "3D Sound Settings".