There was plenty of commercial compact cassettes recorded with Dolby B (Dolby symbol on the label). Dolby C was much more effective but less common.
Dolby NR encoding - did it ever work
What I mean is, if you record something with Dolby NR engaged, the sound should have the high frequencies boosted and the noise floor unaffected during playback without Dolby NR engaged. I had a Kenwood tape deck that would reduce the noise floor during recording, which isn't right. I am considering buying a new, collectible tape player.