Many people have tried to find a method of connecting the world of color with world of sound. After all both can be described with frequencies. The first ones as with many other inventions were ancient Chinese. That is why Colorophone logo reminds a Chinese sign which means "eye". Quite a lot of previous attempts were organized around direct connection between light and sound frequencies (see Fred Collopy's chart below). This leads to a problem when we try to identify color by associated sound. Only people who have absolute pitch can do that.