Hi, there is no more about:permissions page.

The usual behavior is for pages to ask for permission and for Firefox to drop down a panel from the left end of the address bar to get your confirmation. If you don't see that panel, you can try using the Permissions panel of the Page Info dialog. Here's how:

While you are on the page that you want to have permission, call up Page Info using any of these:

• right-click a blank area of the page and choose View Page Info > Permissions
• (menu bar) Tools menu > Page Info > Permissions
• click the padlock or "i" icon to the left of the site address, then the ">" icon, then More Information > Permissions

Scroll down to "Use the Microphone" and uncheck the "Use default" box; a bullet should appear in front of "Always Ask". Click the permission you prefer, presumably "Allow".

Changes you make in this dialog are saved as you go, so after making the change, you can close the dialog.

Does that work?

Note that some sites may use the Flash plugin for audio. The plugin notification icon would appear at the left end of the address bar and looks like a small gray Lego block. If it you see it there, click it to check whether the page has permission to use Flash.

Hmm, actually, your browser reported a very old version of Flash:

Shockwave Flash 19.0

Please see this article for update steps: Flash Plugin - Keep it up to date and troubleshoot problems.