How do i set the microphone permissions for the Chrome extension?

The short story:

in the address bar in Chrome,  

chrome://settings/content/microphone

You can select the microphone that you use and deny access

The long story:

1. Click the Chrome menu  on the browser toolbar.
2. Select Settings.
3. Click Show advanced settings.
4. In the "Privacy" section, click Content settings.
5. In the "Media" section:
   • Ask when a site requires access to your camera and microphone: Select this option if you want Chrome to alert you whenever a site requests access to your camera and microphone.
   • Do not allow sites to access your camera and microphone: Select this option to automatically deny any site requests to access your camera and microphone.

6. Click Manage exceptions to remove previously-granted permissions for specific sites.