These are requirements in order to hear/ talk to people on the server ( Do this also if you don't have a mic )
1. You must install teamspeak 3 ( https://www.teamspeak.com/teamspeak3 )
2. Click download and wait till Teamspeak finishes downloading
3. Install GSpeak Easy Installer ( http://www.sneakyrocks.de/gspeak )
4. Click Download Installer
5. Open up the file
6. Allow it to make changes to your computer
7. Make sure its on Version 1.5 and click continue
8. It should automatically find the path for both Teamspeak, and Garry's Mod ( If not set the path ) My location for Teamspeak - C:\Users\manny\AppData\Local\TeamSpeak 3 Client
9. Click Install ( Make sure Garry's Mod & Teamspeak is closed )
10. Load Up Garry's Mod and your done!