So I am looking for a way to wake the phone by voice, is it possible?
How about simply preventing the phone from going to sleep?
No need to root the phone, just put it in developer mode.
I forget the exact steps but it is something like tap Settings > About Phone
scroll down to Build Number near the bottom and tap that 7 times.
The first few times it wont look like it is doing anything, then it will count down with each tap.
This creates a new menu entry called Developer Tools, or maybe its Developer Settings which are mainly for debugging. But developers do not want the phone to sleep while debugging, so there is an option to prevent going to sleep while the phone is plugged in.
So all you need to do after that is keep the phone plugged into a charger and it will not go to sleep.