Wikipedia says there are two possible pronunciations for »Lejeune Dirichlet« (last name of Johann Peter Gustav Lejeune Dirichlet):
- [ləˈʒœn diʀiˈkleː]
- [ləˈʒœn diʀiˈʃleː]
I do not speak french, so i have no idea if one of them (or even both) are correct french pronunciations.
If you would apply German rules only, you would get one of those:
- [leˈjɔɪ̯nə diʀiçˈleːt]
- [leˈjɔɪ̯nə diʀiçˈleː]
(You also might end up with a different stressing of the syllables in the first part: [ˈlejɔɪ̯nə], but this is not the topic of this question.)
The first part of his last name (Lejeune) is so far away from patterns for German words, and so typical french, that almost every German native speaker will use a french pronunciation for it. So I think only less than 1 % of German native speakers will say [leˈjɔɪ̯nə], and almost everybody will use the correct french pronunciation, even those who don't speak french (like me).
The second part looks a little more German (although of course it definitely has a french origin), but still doesn't match exactly the usual patterns for German words.
This would match perfect:
Dirichlett [diʀiçˈlɛt]
Because ∙ett (with double t) at the end of a word (fett, Brett, Bett, ...) is a typical German ending with a short and stressed [ɛ] and a clearly hearable unvoiced [t].
But ∙let at the end of a word is rare, and you find it only in foreign words and loanwords like Athlet, obsolet, Pamphlet, Outlet, Fillet, Couplet, where the last two examples are pronounces with a silent t (i.e without a [t]-sound) and the others with a hearable t. So, for Dirichlet it is unclear how to pronounce it if you try to pronounce it in a German way.
I often did read the name of the famous mathematician, but I never ever did hear it (and as said before: I have no idea about rules for french pronunciation). So I would have pronounced it this way:
- [diʀiçˈleː]
[di] as in »direkt«
[ʀiç] as in »Richter«
[leː] as in »Fillet«
This means, I would have pronounced:
- with [ç] for »ch« instead of [k] or [ʃ] (which obviously is wrong, as I know since my researches for this answer)
- without a [t] at the end
- Are there Germans living today whose last name is "Dirichlet," and if so, how do they pronounce their own name?
I used some search engines that are specialized to find names of persons, but I did not find a single person with this name in Germany or Austria.
- Do we have any linguistic evidence for how "Dirichlet" would likely have been pronounced in mid-19th century Germany?
Modern German is full of English foreign words and loanword, but most of them was included into German Language after WW II. This is, because in this period of time German had very intense contact with English language.
But German also is full of french loanwords (like Chef, Frisör, Büro, Affäre, Budget, Café, Cousin, ...) which all became part of German language in 19th century or even before.
So at least in upper class society, French and French pronunciation was much more part of daily life for German native speakers than today. And this makes me believe, that at least among scholarly persons the french pronunciation of Dirichlet was standard in mid-19th century Germany.