There are many types of talking in this recording. For this, when Siri talk, it's like to be someone talking in front of us. Then apple slices the recording into pieces and gathered them by the different algorithm. For this, Siri can answer our any question. Siri can speak which wasn't record. Apple works to develop Siri. Hope that in future, Siri will understand us more properly and solve our problems so easily. However, you can setup Siri on your iPhone 5, 5s, 6, 6s, 6 plus, 7, 7 plus, 8, 8 plus and iPhone X.