Why Sounds and Not Words?
There are 2 reasons. First, if it used words, it will be useless for people who have always been blind, colour will just represent a word. Whereas by using sounds, the person can generate an idea of how the "colour" is, as they have the concept in their minds, no matter if they haven't ever seen them.
The other reason is the cost. One of the main reasons why I worked on making my device cheap is because otherwise most of the blind people may not be able to acces to it. Voice synthesizers cost over 70 USD, while buzzer speakers cost cents of dollar.