FaceOri: Tracking Head Position and Orientation Using Ultrasonic Ranging on Earphones

Yuntao Wang, Jiexin Deng, Ishan Chatterjee, Farshid Salemi Parizi, Yuzhou Zhuang, Yukang Yan, Shwetak Patel, Yuanchun Shi


Face orientation can often indicate users’ intended interaction tar- get. In this paper, we propose FaceOri, a novel face tracking tech- nique based on acoustic ranging using earphones. FaceOri can leverage the speaker on a commodity device to emit an ultrasonic chirp, which is picked up by the set of microphones on the user’s earphone, and then processed to calculate the distance from each microphone to the device. These measurements are used to derive the user’s face orientation and distance with respect to the device. We conduct a ground truth comparison and user study to evaluate FaceOri’s performance. The results show that the system can de- termine whether the user orients to the device at a 93.5% accuracy within a 1.5 meters range. Furthermore, FaceOri can continuously track user’s head orientation with a median absolute error of 10.9 mm in the distance, 3.7◦ in yaw, and 5.8◦ in pitch. FaceOri can allow for convenient hands-free control of devices and produce more intelligent context-aware interactions.