Subliminal Talk

Just curious but would it be at all possible to have subliminals that function in the range of say 1-3khz, where theres a lot of bass or heavier tones?

Certainly, but why you would do that? It would be impossible to sleep with that or very hard.

I have a passive brain fitness audio that I like to play during the night. Problem is that the frequencies interfere with that of the subliminal.

What sort of brain fitness audio are you referring to?