The Castle. (2025, July 13). Wikiquote. Retrieved November 26, 2025, from https://en.wikiquote.org/w/index.php?title=The_Castle&oldid=3777848.
Thus, availing itself of the FFR phenomenon, and using the technique of “beat” frequencies, the Gateway system uses Hemi—Sync and other audio techniques employing the FFR phenomenon to introduce a variety of frequencies which are played at a virtually subliminal, marginally audible level.