Mumble is an open-source VoIP program that allows people to connect and communicate with a microphone or other input device. It is comparable to other popular programs like Ventrilo, TeamSpeak, or Roger Wilco. The main difference is that it's open source, uses the CELT high quality voice codec and is completely
free to use or host. It also has unique features such as customizable in-game overlays, copy / pasting images, HTML, and tons of other stuff.
Download Mumble here:
http://mumble.sourceforge.net/
Then just click here to connect to the NoXiousNet server!
IP: mumble.noxiousnet.com
Port: 64738
Text-to-speach is on by default. You can turn it off by pressing Configure at the top and ticking off "Text-To-Speach"
You can read more by clicking the "C" next to a channel's name once you get in.