I think like double tap to wake.... If it isn't on the low voltage core, like moto x always listening is, its never gonna be battery friendly. But people wanted....they got it...kinda. Better than having to be on a certain screen anyway. Just now audio in is listening to every sound it hears.
Sent from my new HTC One M8, N7, Moto X, GTab3 or S2.

Need help with poor battery life? Any device welcome, even tho its an N5 thread. Please specify if on a device other than N5. Lots of info in first 4 posts! >>>>
[Battery Life Help] Troubleshoot Battery Issues Here....and Tips