A prominent scholar of early Chinese writing and books at the University of Chicago recently passed away:
The New York Times "pronouncer" for "Tsien" is "chee-AHN". That is very far from the mark. Even for those who are not familiar with the niceties of Chinese consonants and vowels, "chee-AHN" doesn't sound remotely right because "Tsien" (like the vast majority of Chinese surnames) is one syllable, but "chee-AHN" makes it seem to have two syllables. Moreover, Chinese is tonal, whereas the "AHN" of the pronouncer makes it seem to have emphasis on the second, (non-existent) syllable.