Setup > Voice (Tab)
Uncheck "Use Push To Talk Hotkey (PTT mode)" - left side, second from top.
Adjust Sensitivity and Silience Time. Sensitivity is obvious. Silence time is the required duration of silence after you stop talking before it will stop transmitting. If you set it too low, it can result in your transmission cutting out during a regular speaking pattern. Too high means that you end up with long trails of an open mic after you stop talking, which is annoying to listeners.
Use the Monitor and/or Test modes at the bottom to determine if your settings work well.
Keep in mind that while voice activation mode is nice for the user, it can often prove very annoying to other people on the server. They don't want to hear you munching on some chips, breathing loudly or yelling at your dog, so use it responsibly.
Sindraya, Assassin
<Ravensflyte>
"Oh, hell no," Kylar said. "You cannot fly. Tell me you can't fly."
[Sindrak (DoK), Wingus (Choppa)] | [Drakhon (Thane)]