I assume that you are referring to the plug-in that I posted here: Silent Subliminals [solved?] - #3 by steve
and the code that Edgar-rft posted here: Silent Subliminals [solved?]
The plug-in that I posted contains the same code as was posted by Edgar.
The difference is that Edgar’s post has to be copied into the Nyquist Prompt (Nyquist Prompt - Audacity Manual) every time you want to use it, whereas I posted a plug-in that can be installed. When installed and enabled, it will be available in the bottom section of the Effect menu.
Installation instructions for Nyquist plug-ins are here: Installing Nyquist Plug-ins