With the radiohead track with the delay decreasing from 60 ms to 0 ms, you'll notice that at first you can clearly tell there are two tracks out of synch with each other. Gradually the two tracks merge into one with severely combed frequency content. As the delay decreases to 0ms, the track starts to sound normal again.

With the click train, we start with no delay. Then we set a 60 ms delay between the two clicks and gradually decrease to 0 ms. At about 5 ms the clicks start to sound like a single click. At about 1 ms, the comb filter starts to become very audible (and stays that way at .5, .1, and .05 ms delay. When we get to psychoacoustics next week the reason the comb filter is only noticeable from about .05 ms to 1 ms on the click train will be explained.