Prior to the 6S the phone had to be plugged in for the wake word ("Hey Siri") to work, but as of the iPhone 6S you can do it when running from battery. As you s

Prior to the 6S the phone had to be plugged in for the wake word ("Hey Siri") to work, but as of the iPhone 6S you can do it when running from battery. As you say, the microphone is not particular good at distance.