updated 10:04 am EST, Tue February 18, 2014
Tech could even theoretically monitor mental states
Apple has won rights to a US patent on a biometric headphone system. The technology would track factors like temperature, heart rate, and/or perspiration, using embedded sensors. The sensors could be embedded into the rim of a speaker, or broken out into other components, such as ear clips or inline remotes. Apple also suggests integrating one or more accelerometers for tracking movement, in the latter case recording multiple axes.
One unusual aspect of the patent is the suggestion that headphones could track "psychological" data. Apple doesn't explain how this would be done, but it could involve interpreting the combination of various statistics, or some form of EKG monitoring.
Apple moreover proposes that the accelerometers could be used for gesture controls. Skipping music tracks, for instance, might be done by tilting or rotating the head. Because of the possibility of making mistakes, gestures would require hitting a button first.
Apple is believed to be pursuing biometrics in shipping products, but via the iWatch instead of headphones. The company has hired a number of health and fitness experts for the project during the past year. It's still unclear when the iWatch might ship, but the current expectation is late in the year, since Apple is rumored to be developing a "Healthbook" app for iOS 8.