Benjamin Mayo, writing for 9 to 5 Mac:
When using ‘Hey Siri’ voice activation in a room with multiple nearby devices, only one device will respond. For example, with iOS 10 installed, an iPhone 6s is smart enough to stop listening for voice input if an iPad Pro is also listening.
I wonder how this works in practice. Would it prevent my wife’s iPhone, in close proximity to mine, from activating when I say “Hey Siri” or does it only work for devices with the same iCloud account?