I partly agree with what you say here, pianowhisper, but I'd qualify a few things.
I see sheet music as a new language pretty much.
I agree, but I think we might mean different things! I'm guessing you mean "a different language from English, etc.", where I would say it's also a different language from actual music.
Playing music without even bothering to learn how to read it is like trying to speak a different language without comprehending how it works.
I think that's an unnecessarily academic view. Millions of people understand how music "works" without knowing a dot of it.
As if you were solely speaking words out trying to imitate what a native speaker said,
And millions of people learn to speak a language that way. We all learn our native language exactly like that, by ear, by imitation, repetition and verbal correction, before we start adding the recognition of written words. And I'm pretty sure people often learn a second language exactly like that, especially if it has an uncustomary alphabet. Furthermore, when learning a second language, it is commonly asserted that the best thing you can do is surround yourself with native speakers and converse with them. You have probably talked to people who didn't learn to read and write English, without knowing it.
Humans had languages for hundreds of thousands of years before we invented writing, and it is reasonable to induce that illiterate peoples memorized stories, music, poetry and all manner of things by imitation, repetition and verbal correction. We should also note that our Western tradition has run roughshod over ethnic traditions, some of which will have involved complex non-literate musical forms.
Writing always invovles a sclerotic process where subtleties that are hard to encapsulate are ignored or badly approximated. How exactly would a particular regional accent be codified? We know what they sound like; we can imitate them, but it would be virtually impossible to put them on a page precisely (although linguists have symbols that approximate the sounds - without the referent to listen to, we would have nothing for the symbol to
mean).
This is the sort of rich, subtle information that musical script loses, hence why there are vast differences in people's attempts to reconstruct historic interpretations of classical or other early music, and why modern composers sometimes write reams of instructions in their native language to accompany their scores, or single bars, or notes. Modern composing often involves breaking out of the binds that notation inevitably places on communicating what is essentially a vibratory experience (or the imagination of one). Of course, mainstream classical musicians forget this, because they stay within the limits of what they can read off a page, and eventually think the map is the territory.
or trying to write phrases down solely by copying the characters one after the other (think of a language with a totally different alphabet you're not familiarized with, and you try to write words just by copying the characters instead of understanding the alphabet itself). Sure, to a certain extent, the results can be reasonable, but soon the effectiveness of this solution is lost and then you're forced to improve your proficiency in that.
With music it is similar.
But this is a different scenario, the copying of different
symbols. Music itself is not symbols, it is
pressure waves, and the human brain has innate abilities to make
emotional and - to some extent -
schematic sense out of it. I would agree that writing it down and learning music theory allow a much
richer analysis of "how it works", with the caveats above.
In my point of view, the "language" in this case is the score itself. It becomes very hard to understand music and what it is saying without... well... utilizing its language.
When people say music is "a universal language", it's precisely because it's not the score itself (clearly, because we could translate that into any number of other notation systems). And you can sit with a three-year-old child and sing The Wheels on the Bus, and they're utilizing the musical language.