If I get drunk, I can picture colors for different instruments. Drums, wind, and string instruments are varying shades of red, yellow and orange depending on pitch. Synthesizers are always cool colors depending on their sound. The more artificial they sound, the further away they are from yellow or red for purple and green synthesizers) Human voices are pink if high pitched and red if low pitched.
I definitely don’t want to rely on them too much, otherwise the game will become mostly going to a market. That being said, I do like the idea of using the night market to introduce different NPCs that would be useful to the players later on even if there’s not an immediate story arc that plays out.