Apple introduced Siri personal assistant with the new iPhone 4S. Siri, which is activated by a short press of the home button, also gives users the option to activate Siri using a feature called Raise to Speak. On Wednesday, a tear down from iFixit revealed that Apple has embedded an infrared sensor close to the ambient light sensor in order to determine when the user raises the iPhone 4S close to their face.
When a user brings the iPhone 4S closer to the face Siri is automatically activated. The infrared sensor is lit up whenever the screen on the iPhone is lit but is not visible to the naked eye. The new IR added to the Raise to Speak feature could be yet another reason why Apple would not bring Siri to older hardware such as the iPhone 4, 3GS, and 3G.
This also brings up a number of questions about whether this will be a drain on battery life, and although IR sensors typically use the least amount of battery, it is still a concern. iFixit has posted a video on how the IR works, and how they discovered that the sensor was there. Check out the video below and let us know if you use “Raise to speak” feature often.