Learning the grammar and vocabulary for a new language is relatively easy for most people. There may be a steeper learning curve for inflected languages and those written with symbols as compared to alphabets, but the basic “subject goes here, verb goes here, adjective attaches here, this ending is for plurals” are not that difficult. And learning a bit of the literature tends to come fairly easily. You may get tossed something like an article written in the German “academic” verb tense (almost gone and used only for writing that is pure fact) and poetry is always a challenge, but grammar and vocabulary and some literature are easy to master. Spoken languages perhaps even more so, since you are not having to learn the language specific and culture specific tropes and ideas that appear in different genres and periods. But the rhythm of language . . . ah, that’s a different story.
English speakers tend to take for granted that different regions have different accents, cadences, and vocabulary. BBC English is not Brooklyn street English is not the North Dakota-Minnesota lilt (bit of Scandinavian tossed in) or the flat “Midwestern” sound of Nebraska-Iowa-Indiana. Southern accents have been a stock feature in all kinds of academic, humorous, and other writing forever. And someone with a decent ear can tell a Canadian from one region from a Canadian from a different region (even if she’s not from Newfoundland or speaking French just to tick you off). New Zealanders are different from Aussies are different from someone from Boston MA from someone from Boston England. And the rhythm of the words is as important as the vocabulary and pronunciation.
I had not really thought about it until being immersed in German. You see, I have a relatively limited working vocabulary for “normal” conversation, and a far greater passive and technical vocabulary. I’ve traveled with people who lived on the economy in Germany or Austria, picked up an enormous working vocabulary, and can speak easily to everyone from the tax police to bar tenders to car rental agents without trouble. But they always sound like Americans speaking German. If I get two sentences out, especially in Bavaria and Austria, people assume that I’m either a native speaker or very close. In other parts of Germany people think that I’m a French-speaker speaking German. Why?
The rhythm is what fools them. I suspect it is because of having had musical training since I was 3-4 years old, and being exposed to music since I was -9 months, I pick up patterns and rhythms without realizing it (as long as I’m not trying to dance.) Over the years I’m absorbed the southern German rhythms, so when I talk, the words flow with a tiny break between them, almost what you’d call a “choral lift.” I don’t think about it any more, it just happens. And that flow tricks the ear so that I sound very much like a native speaker, at least until I hang up on vocabulary.
There’s a reporter for NPR who covers China (I don’t recall the gent’s name). He’s fascinating to listen to because his Chinese is so good and he’s so immersed that he’s picked up the Chinese rhythm when he speaks English.
(As an aside, in S. M. Sterling’s book The Peshawar Lancers he comments that the English of the transplanted Empire now speak with the Hindustani “twitter” and think that the South African and English English-speakers sound coarse and strange.)
It’s probably just as well that most teachers of foreign languages do not emphasize the importance of rhythm when they teach. Grammar and vocabulary are enough of a handful for anyone to learn. If you have the “ear” to catch more, it works wonderfully, but otherwise? Grammar and vocabulary will get you very far indeed.