Hi there,

Please work through the following list in this order:

1.) Make sure that you're using headphones for monitoring when you're recording your second/voice track. If you use speakers, you will obviously get a loop from the speakers to your mic. This one seems kind of obvious, but I got to include it in the list for completeness' sake.

2.) Configure your Windows/sound card recording mixer in a way that it will exclusively record from the particular socket that you're connecting to (in this case your microphone socket). Make sure it's not picking up signals from other sources, e.g. the entire Stereo Mix. Most likely, this is the culprit here. Depending on whether you're using the standard Windows mixer or a proprietary mixer interface and depending on what sound hardware you're using, the procedure to configure this might differ.

3.) If the two points above don't remedy the issue, this is a technical problem of your sound driver. I've dealt with this very issue before in connection with, I believe, some slightly older Realtek AC 97 type on-board audio hardware. However, the available driver update for that sound chipset did resolve the problem.

I hope this helps.