With the iPhone 4S it appears the biggest thing is the new voice assistant Siri, and with anything new to the game, most want to know every little detail as to just why the feature works the way it does, and today we learn a little more about Siri and how it works courtesy of a video, which we have for your viewing pleasure below.

Apparently if you have every wondered just how Siri reacts so quickly when you bring the iPhone 4S up to speak, well it’s all down to a tiny little sensor, an infrared LED to be exact that has been added to the proximity sensor.

Now the use of a proximity sensor on the iPhone isn’t anything new as its always been there using infrared all the time your are speaking on your iOS device, however with the iPhone 4S that little sensor has been tweaked a little.

The How Siri knows you are there video below, which comes our way courtesy of the guys over at TiPb shows MJ of iFixit explaining that the tweaked proximity sensor now turns on every time the screen is activated rather than only when placing a call as in previous iPhone handsets.

Anyway, the iFixit people can explain it far better than I, so I’ll leave it right there and let you head on down to check out the footage.

The big question is though is, perhaps the tweaked infrared LED proximity sensor is the reason why Apple isn’t delivering Siri to older devices, however no doubt the cleverness of the hackers out there they will find some way of making Siri fully work on other devices regardless…enjoy the footage.

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