The document describes research into developing a quantitative digital backchannel system to measure audience perception in large lectures. It outlines requirements for the system including supporting many devices, maximizing meaningful information while keeping it simple, and continuous backchannel activity. The system was implemented and tested in a lecture with 100 students, with findings like 75% participation rate and that activity decreased over time. The conclusion is that dimensions, BYOD support, user experience, and motivating participation are important for an effective quantitative backchannel system.