There's a forum about it on Windows here: [I'm not as familiar with Windows computers, but I believe there is an option somewhere in your Microphone Properties to turn this on, but I'm not 100% sure. LineIn allows you to play audio from other devices (like microphones) live through your speakers. So the way that you fix this on a Mac is with a program called LineIn. Now if you play something on your iPod, you're probably not going to hear anything coming through your computer.
Now take the other end and plug it into the microphone port (input) of your computer. Start out by taking your audio cable and plugging one end into the headphone jack of your Apple device.