Then, go to your Teamspeak 3 folder : sound/default ---> make a new folder called Backup and move all the files in default to the new folder you've just made.
Go to the .rar you just downloaded, extract them to the default folder.
Launch Teamspeak. Click on the top bar Settings ->Options. A window will pop out. Go to Playback and tick the 2 last boxes (Own client plays mic clicks & other clients play mic click). Click Apply and OK and you're good to go