Daniel wants to know how "Hey Siri" in iOS 8 can affect battery life. Leo says it always listens, so it's going to affect battery life, which is why it only works when the phone is plugged in. The good news is, he can turn it off. But it doesn't listen how he thinks it does -- it's comparing wave forms and if the wave form matches the wave form of "hey siri," then it wakes up. So it's not really eavesdropping on him, per se.