HTML5音频如何防止浏览器麦克风拾取所有声音

In my sample asp.net/vb.net project for HTML5 audio, using Matt Diamond's recorder.js, when I grant any browser access to my microphone, I can hear every noise around me in the headset speakers (e.g., someone typing next to me, people speaking, etc). I'm using a Logitech USB headset, but am not sure the specific model as they're provided through work.In my sample asp.net/vb.net project for HTML5 a