How to have a audio output to arduino meanwhile the speaker can play the audio

I now have my audio analyzer which required the Left Channel,Right Channel and Ground Pin.A audio jack socket is used to receive the audio from computer trough audio cable.While the audio cable is plug to computer , my speaker was no longer work.So what is the solution for it?Thank you!!

You've got a laptop, right? No... When you plug-in headphones or external speakers the internal speakers turn-off and there's usually no way to override that behavior.

You can use a [u]Y-Splitter[/u] with external speakers or headphones. Or, you can add a "pass-thru" jack on the analyzer so you can plug-in headphones/speakers.