It might be a Flash plugin conflict. Latest versions of Chrome have this tendency to have two to three different versions of Flash enabled at the same time. In particular, Chrome's "Pepper Flash" causes a ton of problems with TokBox. Here's some tips to try and get Flash to play nice with TokBox in Chrome. Personally, I can't get TokBox to play nice, so I just use Google Hangouts for my video chat needs.
Oh. And since this hasn't been mentioned yet, you can increase/decrease the volume of your own microphone volume settings in TokBox. In case you haven't tried it, increase your volume and have your players increase the volume on your portrait on their end too.