You'll need a card and software. Do a google search and you'll companies like this.
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You might be interested in our test kits and software that is used for this purpose. It has it's own built in generator and loops through one of the channels in you sound card--so you don't need a really great sound card to get good measurements. Of course, the better the card, the better the measurements.
Rives Audio Software
I used to have a full copy for some of these programs, but i don't know where it went to. Either way, Spectralab offers some truly excellent software that is available as a free download on a time limited basis. Hope this helps. Sean