Every method is used for creating reality of illusion.
Those are utilized for giving reality and reliance to people and that lives in this world, the color and the sound are one of them.
Though color and sound have some meaning, first let's talk from there.
As you know, if the world that you live doesn't have light, you can't see anything, and maybe you doubt even your existence.
Further if you can't hear voice as a sound indicating other existence, and if you can't see the individual, it is difficult to understand these exists.
If all of colors and sounds are lost, it is difficult to form real society.
The word is one of the means that you human being use understanding each other.
Human beings think the only method you have understanding each other is the word, but this is wrong.
The word without emotion mislead, and it gives to people several influences.
The word that people use can't expresses all of meaning.
Its important energy comes from the speaker during human communication.
Way of talking, and using words.
If you can talk with face to face, listener could understand speaker expression that think about only oneself or others from being transmitted speaker face.