Why are sight and sound prerequisites for intelligence?
To answer your question, we must first ask the question What is defined as intelligence? 

A googling will tell you that most people believe intelligence to be something related to apes or even more conservatively to humans. But, I find this to be a bit unpragmatic. The closest level of abstraction I find towards defining intelligence is this wiki on Animal Cognition. Having said so, I personally would define intelligence on a much more abstract level. 

Intelligence can be broadly defined as a learned response towards an external stimulus, providing the organism with an increased fitness/survival within it's ecosystem.

So Intelligence can be broken down into two parts 


Memory of a stimulus
A programmed response towards that stimulus


This is a very famous video showcasing intelligence in the animal world; Crow Intelligence test 

But My objective is to state that sight and sound are are not at all prerequisites of intelligence. 

This paper from way back in 2014 is I think the best that I can state

Memory and Fitness Optimization of Bacteria under Fluctuating Environments

In this particular paper the authors test the capacity of E coli to produce a response within fluctuating environments, and they find that as the generations progress the later generations take lesser time to produce a response towards the stimulus. They also note that what happens if the prior external environmental state is restored. In such a case later generations become optimised for that particular state. 

This is a very good example of memory which is stored at the level of DNA, and a level of intelligence is manifested in a microbial system. So therefore, can you really state that "sight- and sound" are pre-requisites of intelligence. I would say No They are not, that would be an over-simplistic way of what intelligence really is.