Mr. Dude: Something is not working right for me. I am using stereo headphones (Shure SRH840). I'm playing the vid through a Dell Inspiron 15 laptop. At 0:35 of this vid there is a 200 Hz tone in the left channel. As expected, I can hear it in the left channel and not the right channel (the right channel is silent). But when you add the 205 Hz signal to the right channel, I can hear the warbling in both the left and right channel independently. When I perform the check you recommend at 1:00, I hear a warble, not a pure tone, in both channels. Is this an error in your YouTube vid recording, or is there an error somewhere else?
@Meredith If it's a Windows machine, look in the bottom-right corner -- you could have Dolby, Nahimic, Realtek ... (there are too many possibilities to list here).
Lance Kaz