I just got a message back from Cardo Support. Here is what they say about it. It is kind of amazing (to me at least) because it gives another perspective on things as far as I am concerned. Read this about the Vox function and the settings:
Originally Posted by Cardo Support
"The high setting is what you want to use for the Vox setting if you have a quiet vehicle. However the technique you use to trigger the intercom is also important to how easy or hard it is to open the connection when using only your voice to start the connection. The system is looking for a long drawn out sound, like a long "Hellllllloooooooo" that lasts for a longer time than you might feel is comfortable. Short sharp sounds that are yelled are not likely to trigger the intercom, such as yelling or screaming something like a quick "Hey!" The system is looking for a long drawn out human sounding word (it does not matter what word) in order to get its attention and for it to be able to tell the difference between you and whatever background noise there is. It normally does much better with some background noise, unless you change the settings, as you can now do on the G4."