On the iPhone 4S, you can trigger Siri in one of two ways. You can either long press the home button, or you can turn on the “Raise to Speak” option under System Preferences and trigger Siri just by lifting your 4S towards your face.
That might not seem like a big deal, but that little feature led to Apple redesigning the way the iPhone’s IR proximity sensor works in the iPhone 4S.
As the video above shows, on the iPhone 4, the IR proximity light only came on when you made a call, started Skype or launched another app that might need to dim the screen to conserve battery life by shutting down the screen when it is close to your face.
With the iPhone 4S, though, the IR sensor is, in the words of iFixIt, almost neurotic about wondering how close your face is to the device. Not just when you’re on a call… all the time!
As it turns out, it all has to do with Siri’s “Raise to Speak” feature. The IR light has to poll constantly to see if it is being raised to a user’s face, at which point, it will launch Siri.
Christian Zibreg over at 9to5Mac seems to think that this is why Siri can’t run on any pre-iPhone 4S hardware, but I don’t see anything here that suggests this is a hardware limitation: it’s the iPhone 4S operating system that is telling the IR sensor to keep polling. That should be emulable when a proper Siri jailbreak solution comes out. It is, however, a nice example of Apple getting even the small details right.
John Brownlee is a writer for Fast Company, and a contributing writer here at CoM. He has also written for Wired, Playboy, Boing Boing, Popular Mechanics, VentureBeat, and Gizmodo. He lives in Boston with his wife and two parakeets. You can follow him here on Twitter.
16 responses to “Why Siri Is “Neurotically” Obsessed With How Close Your Face Is [Video]”
“…app that might need to dim the screen to conserve battery life by shutting down the screen…”
So which is it, dim or shut down? Editor, where are you…
I wonder if this (the IR sensor/camera turned on) is the cause of the low battery life that many users are reporting.
I fell in love when she said “Infrared LED proximity sensor.”
Be still my beating heart!
The hot nerdy type… love it.. now what was she talking about? lol
additional cause for battery drain??
No, IR is not a battery-intensive task.
Yea, was about to point that out too…
I’d say it’s shutting it off as that is what phone and skype does based on the proximity sensor, the only screen dimming going on is just the normal adjustment to ambient light.
Further, when making a call the screen isn’t shut off to conserve battery, it’s shut off so you wont accidentally “press” any of the the onscreen buttons with your cheek…
I was thinking the same thing as Kai. It may not be an intense use of the battery, but it’s a constant use, so it’s more than previous phones.