If my Android phone is off, it's off. It doesn't turn itself on, period. If it's just idle, screen off, with lots of stuff asleep, sure it will "wake up" in that the screen turns on, and sound an alarm. But that's it.
That is not true at all for Android. Ask any Android developer. it is entirely possible to code an alarm callback that will not activate the screen at all, but can use a network to send and recieve data.
That's generally what's meant by "wake up." This would seem to indicate the phone's not really "off," though I couldn't say how possible it is to tap into the mic in this state.
If my Android phone is off, it's off. It doesn't turn itself on, period. If it's just idle, screen off, with lots of stuff asleep, sure it will "wake up" in that the screen turns on, and sound an alarm. But that's it.