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Prior to joining a BigBlueButton session, you should ask your learners to run the test found at https://testwww.webrtc-experiment.orgcom. If any of the tests fail, it's possible that one of the services (e.g. audio, video and/or screen sharing) will fail. When running the "Microphone" test, the user should be speaking into their microphone. Even if the microphone is connected, if the user is silent during this test, the test will report a failure because it cannot hear the user.
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