Using Parametric EQ for Room Echo

I think you may be referring to this video:

However, as Steve mentions, DeReverb is AMAZING and does so much more than shown in this video with one simple slider to increase intensity. Give it a go!

Firstly, you can't reduce the effect of the acoustic of a room using EQ at all - all you can do is cut back some of the frequencies at which it sounds more prominent, but in doing this you cut back the actual signal at these frequencies just as much - achieving nothing except an altered frequency response, which may be undesirable.

Secondly, what the heck is a 'sine curve' in this context? The curve of a sine wave applies to a single frequency only, and has nothing to do with anything you can do with parametric EQ. A sine curve is only a mathematical function; y = a sin (bx + c)

So no, I don't know what you are talking about. You might, though, try investigating Audition's DeReverb effect. At least this attempts to address the real problems with room tone, even though it can't cure them either.