Just spitballing ideas here, but isn't this just what companies also use when combining tones into a three or four-tone jingle? Also called an "interval signal" when used on the radio - it's a short, as few as three notes/chimes/tones that basically brainwash people into associating it with the station.
Most Americans know the 3-tone jingle NBC has used for nearly a century. The notes are apparently a G-E-C motif because NBC used to be owned by the General Electric Corporation. I mean...if that's not an audio sigil, I don't know what is.
Intel for years had commercials with a 4-tone jingle as well. AT&T had a 4-tone jingle in their ads. The first 4 notes of "Here comes the bride" are iconic. Five-note jingles would be T-mobile and McDonald's. Netflix uses 2 beats and a melodic sound.
Or the Macintosh startup chime, which is a combination of tones. THX sound, same thing, a combination of tones.
Each of these are basically "logo images you can hear" for a reason. Might be a way to work on something and invent your own.
Additionally, on the topic of subliminal messaging, it's been debunked as useless for decades. Just like quicksand in cartoons and old TV shows, even attempted to be used by companies, it never produced results.