This is our situation: We have a cashier window which only has 2 holes; 1 for talking and another for payments. Currently, our cashier shouts most of the time so a customer can hear her voice.

Our solution (though I can't make it work): bought an additional sound card, headset and mic. Installed the add'l sound card in the PC, placed the PC speaker on the other side of the window, and let the cashier use the headset. I interchanged the connection of the speaker to the sound card's line out so they can hear each other talking and not hear themselves. (But all of this is only in theory. I still can't make it work.)

I do not know how to immediately output the cashier's voice out to the speaker on the customer's side and the same goes for the customer's voice to the cashier's headset.

I used the speech settings in control panel which tests for voice, but it has an annoying delay and is sometimes slow in audio output. Yahoo Messenger is much faster. Why is that so?

What do I need to do? Do I need to buy software or hardware? or both?

Thanks!!!