High quality audio communication is one of the most important factors of a successful live interactive e-Learning system. Echo cancellation technology plays critical role in ensuring high quality audio communication. The current echo cancellation technology works only when the audio goes in and out of a single computer in a given room. Our Smart classroom e-Learning system [1, 2] requires 3 computers for a given classroom to capture and stream HD video from 5 video cameras placed at different angles or perspectives. It is done to achieve gaze alignment across all the remote participants by showing the appropriate perspective at each remote classroom display based on the current teaching mode of either lecturing or interaction. Since the audio is processed through three computers in a given room, we had to augment traditional echo cancellation technology with new techniques to achieve echo cancellation. In this paper we present 3 echo cancellation techniques, evaluate them against the criteria of factors of smart classroom, and analyze their pros and cons along with the user's feedback.