It sounds like a creepier version of google now which listens for many keywords instead of just one, is it not?

Question for the experts: How much battery would it actually drain if the mic was constantly activated and the app was scanning for keywords. I mean, you could limit the scanning to times were someone actually speaks and otherwise remain in a sleep mode. The keywords are then synced only when the user opens the app.

Did anyone ever check if something similar was mentioned in the google now TOS?