Make sure that:
-your microphone is correctly connected to your computer
-make sure that your microphone is not blocked in the Chrome browser. See troubleshooting steps here http://interstaricp.com/forums/topic/how-to-allow-chrome-browser-access-to-your-camera-microphone/
-your microphone switch [if any] is not muted
-your microphone is selected in the microphone menu in InterStar ICP
-the microphone button in your console is red [microphone on]
– when you speak the “out” indicator above the microphone button is showing the audio signal
-your boothmates who are listening to you did not accidentally click “mute boothmates” button
-your boothmate audio volume is sufficiently loud [boothmate volume slider]