What about lip-reading with reflected Wi-Fi signals :) : https://people.eecs.berkeley.edu/~guanhua/paper/WiHear_MobiCom14.pdf https://people.eecs.berkeley.edu/

What about lip-reading with reflected Wi-Fi signals :) : https://people.eecs.berkeley.edu/~guanhua/paper/WiHear_MobiCom14.pdf https://people.eecs.berkeley.edu/~guanhua/paper/WiHear_MobiC... "WiHear aims to detect human speech by analyzing radio reflections from mouth movements. It requires individual user to train the system extensively, and can recognize only a limited number of words (6 words) with high accuracy."