I just found out that all words that start with "abs-", "obs-" or "obt-" are pronounced with a /p/ instead of a /b/. I know that /b/ is a voiced consonant and /p/, /s/ and /t/ are unvoiced, which seems to be the reason for the change - so that both consonants end up unvoiced. In English the /s/ changes to /z/ (voiced) instead.

  • abstenir - /apstəniʁ/
  • observer - /ɔpsɛʁve/
  • obtenir - /ɔptəniʁ/

Does this happen in the middle of words too? Are there any other combinations where the spelling is voiced but the pronunciation is unvoiced or vice versa?

  • 1
    Just can't make a complete answer right now but I know it's not all the words and that anyway both pronunciations (/ab/ /ap/ - /ɔb/ - /ɔp/) are heard. Listen to a few words on Shtooka, abstenir, obtenir, etc. clearly /b/. Personally I pronounce /b/ after o and a, but I've heard /p/.
    – None
    May 1, 2016 at 7:07
  • 1
    @Laure Thanks for that. I checked two hard-copy dictionaries and they both had only /p/ for all those words. I'm sure it's not as cut-and-dry as that in the "real" world though! I heard /ɔptəniʁ/ on Shtooka and it was borderline between /apstəniʁ/ and /abstəniʁ/. I also tried Forvo with the same results. If you are a native speaker then you are at a disadvantage because you already expect to hear the words a certain way. It's the same for me in English. Some foreigner will point out a strange sound in an English word and until they do, I don't notice it.
    – CJ Dennis
    May 1, 2016 at 7:23
  • en.wiktionary.org/wiki/abstenir transcribed with /b/ one place and /p/ the other. I'm rather used to listening to sounds and when cutting it down I can hear a clear /b/, same when I listen to people next to me. But I also definitely know /p/ can be heard.
    – None
    May 1, 2016 at 7:29
  • For variation a lead could be a north/south divide or maybe a generation one. Can't answer your question - yet - but can point to some readings on the phenomenon (it's called "assimilation régressive"). On Linguistics, OQLF, it's the same phenomenon that will make some people pronounce /mɛt.sɛ̃/ for /mɛd.sɛ̃/ /d/ → /t/ (just an example).
    – None
    May 1, 2016 at 8:28
  • 1
    Hum... When I'm saying it fast I'm saying /apstəniʁ/, if slow /abstəniʁ/.. sounds strange, but that's it.
    – Gautier C
    Jun 1, 2016 at 6:29

2 Answers 2


I personally pronounce these as /bs/ not /ps/, but I've heard it both ways and my sense is that most native speakers wouldn't be able to tell the difference if they heard the same word pronounced both ways. As to the original question of whether this is only at the beginning of words -- no, there's no difference in how these clusters are pronounced between initial and non-initial placement such as "nonobstant", "réabsorption", etc.


When a voiced consonant (b,d,j) is followed by an unvoiced consonant (s,f,t) we're used to pronounce it as un unvoiced one ("p" instead of "b", "sh" instead of "j") but as far as I know, it's not a rule, it's rather a phonetic phenomenon. Actually, it's not impossible to pronounce a clear "b" in "absent", "abscons", "obscurité"; but it would be like passing on a speed bump. Pronouncing a "p", in this case, is easier, and it becomes a habit, even more so when you're fluent in french.

  • I would say this is more an accent issue than a pronounciation issue. Where I live lots of consumns are pronounced "p" or "k" when they are not p or k letters.
    – Webster
    May 2, 2016 at 14:42
  • @Webster It is hard to change voicing in the middle of a consonant cluster in any language but certainly not impossible. In English "observe" is /obzerv/ (I'm using very bad IPA) and in French my dictionaries list it as /opserv/. /observ/ can be said in either language if you concentrate on it and it takes more effort.
    – CJ Dennis
    May 3, 2016 at 3:37

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