Instructions
Right-click on the "World of Warcraft" icon on your computer's desktop. Select the "Properties" option from the pop-up menu that appears.
Click on the "Open File Location" option under the Properties menu's "Shortcut" tab, to open your "World of Warcraft" program files folder.
Open the Data folder inside the program files folder, and open the Sound folder, then the Music folder. The game's sound files will be sorted into several folders such as "Creatures" or "Spells."
Click on the game folder containing the type of sounds you'd like to extract from the game. Hold down the "Ctrl" button on your keyboard, while clicking on the desired MP3 files. After selecting the MP3 files, press the "Ctrl" and "C" buttons on your keyboard simultaneously.
Close the sound folder, and then open the folder you'd like to use to store your MP3 files. Right-click inside of the destination folder, and then select the "Paste" option from the context menu that appears. Your MP3s will be copied to the destination folder.