I am learning the art of hearing various colors and it does not take long to quickly ID A lot of the basic colors. However, with slight changes in color, lets say yellow, The change in tone volume is hard to pick out but is there between bright sun yellow and a slightly redder yellow. What if the tones were replaced with rhythms  such as a drum beat.  Might make it easier to pick out the finer details.....

Bass drum, High hat, Cymbal are just some ideas I have been thinking about what can be done simply and cheaply :-)