Human speech having a constant bitrate seems to indicate that there's a limit in the bandwidth we have when receiving or giving information, where that bandwidth is measured in terms of the actual amount of information, independently of the media. Therefore, in a computer program, what matters is not the number of characters but the actual ideas behind the code. In other words, the more complex the ideas are, the more time we need to process it, independently of the number of characters.

> The intelligibility of a computer program is heavily affected by how clearly the underlying concepts that define a solution to the given problem are mapped into the structures available in the given programming language, and that is obviously heavily affected by the choice of programming language.

I don't think so. Nobody uses "just" a programming language. They use a generic programming language plus libraries (or DSLs) plus their own code that maps the concepts of their problem to code. Unless the problem to be solved is really generic and/or simple, a programming language alone is very very far of having direct mappings from problem to language.

And you can't escape the complexity of the problem at hand. You can hide it, but in this regard there's no difference between hiding it behind a compiler, behind libraries or behind your own code. You still need to understand the problem and the underlying concepts.