I came across a song performed by Daniel Kahn, and I really liked his pronunciation. They say he comes from Detroit. Is this a typical accent for that region? Or is he doing something else?
Kahn speaks Yiddish, though far from perfectly — in this interview, he speaks Standard High German with a slight Yiddish accent peppered with a few Yiddish words. His accent is nevertheless far less American than that of the interviewer. He speaks Standard High German with near native fluency, though in this interview, he couldn’t recall the German word for ‘tent’ (Zelt).
In this interview in English, except for the cot-caught merger and pronouncing the consonant r slightly fronted as is typical in Michigan — also word-final — his English bears few traces of the Northern Cities Vowel Shift. This could be because he also studied theater, where heavy regional accents are usually smoothed out to “broadcast American.”
The reason you’re hearing reduced or unpronounced word-final r’s is not because of German influence or an inexplicable pocket of non-rhotic English in the Motor City, but because he’s a singer. Except in Country & Western, white gospel, and bluegrass, word-final and syllable-final r’s are not sung in any genre of music, mostly because the position of the tongue and the tension in the lips while pronouncing an American r block an open vocal sound. Singing through an American r makes you sound like a car starting or an electric edger.
One of the most common diction errors of non-anglophone singers performing in English is pronouncing r’s where a native speaker most likely would not. In this song from the 2009 European Song Contest, an Icelandic singer manages to reduce the r in over, but not in never, ever, or perfect. It’s a perfect American r, but one which most American singers wouldn’t sing.