Things You'll Need
Instructions
Launch "Half-Life 2." You can do so by double-clicking the icon on your desktop, or opening your "Steam" library and double-clicking on "Half-Life 2" from your games list.
Click "Options." This opens the "Options" window.
Click the "Voice" tab along the top of the "Options" window.
Click the box beside "Enable voice in this game" so that it has a check inside of it.
Click and drag the sliders for the "Send" and "Receive" volumes to your preference. Click "Test Microphone" and speak into your microphone to test the setting.
Click "Apply."