iPhone 4S Incorporates Revamped IR Sensor for Siri's 'Raise to Speak' Feature

Apple's new Siri personal assistant feature on the iPhone 4S includes a "raise to speak" feature that allows Siri to be activated whenever an active iPhone is raised to the user's ear. The device is able to sense the raising action using a proximity sensor capable of detecting how close the user's face is to the screen. The iPhone has always incorporated proximity sensors in order to turn off the device's display during phone calls to prevent accidental input, but Siri's raise to speak feature requires that the device be ready to sense proximity to the user's face at all times.

siri raise to speak
Teardown firm iFixit has gone back to its original teardown of the iPhone 4S to highlight the sensor involved and show how it emits infrared light at all times to support Siri's raise to speak function.

During our iPhone 4S teardown, iFixit buddy Markus noted that the new iPhone had a rather unusual-looking black component next to the ambient light sensor. We didn’t make much of a fuss about it since we were knee-deep in disassembly pictures, but the little black box certainly piqued our curiosity.

Now that the teardown is wrapped up, we’ve re-opened the mystery and made a neat discovery about the 4S: that black component is an infrared LED, and the little bugger almost always wants to know if you’re nearby.

In a video, iFixit demonstrates how the iPhone 4's proximity sensor is only activated while on a phone call, while the sensor on the iPhone 4S is active whenever the device's display is on.

Top Rated Comments

Pooshka Avatar
118 months ago
Does 'Raise to Speak' work for you 100%?

For me, it's hit-and-miss; sometimes the phone registers 'Raise to Speak', sometimes it doesn't. Can be very frustrating. Not sure if something's wrong with my device.
Score: 11 Votes (Like | Disagree)
guzhogi Avatar
118 months ago

I like the private idea of being able to raise the iPhone to speak with Siri, so it's a shame that you can't get it to reply to you in private too.


I wouldn't mind a private chat with the girl in the video. She's kinda cute! :D
Score: 9 Votes (Like | Disagree)
840quadra Avatar
118 months ago
This could potentilaly be why they don't want to support Siri on older devices. :confused:

I am sure Siri would still work, but perhaps they could simply remove the raise to speak feature, or just use the gyroscope and accelerometer to tell the software that the phone is being raised.

Wouldn't an other use for this sensor be for detecting proximity of a person's face? I have seen threads on proximity detector not working well on the iPhone 4 causing spurious inputs for various people. I would be curious if 4s users have less of a problem with this ( my 4 hasn't had issues with the prox sensor, but I may just have a big face :o )
Score: 8 Votes (Like | Disagree)
CaptSaltyJack Avatar
118 months ago

That girl looks funny. Don't really know if I find her very attractive or not attractive at all. Sort of hybrid attractiveness. Very weird.


Cute, but wow, what an irritating & harsh nasally voice :(


You know she's ON this very thread, right? Reading and participating? My god, you folks are socially inept. You two are carved from the same block of people who are like "OMG, A GIRL!!" D.T. is right, some of you need to get out more.
Score: 6 Votes (Like | Disagree)
D.T. Avatar
118 months ago
Some of you guys (and gals?) need to get out more often :D
Score: 6 Votes (Like | Disagree)
melissajenna Avatar
118 months ago

Careful, she lurks here. :D


Cannot believe you just called me out as a lurker. Owned.

As much as "always-on" IR might affect battery life, I'm doubtful that it's responsible for a battery draining at a rate of 10% per hour. My bet's on software.
Score: 5 Votes (Like | Disagree)

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