Just a curious question: Why is "assume" pronounced so funny by many native speakers? I can't think of any other word where "ss" is pronounced like that.

A bit hard to explain via text, but it's like "sh" with something like a speech impediment. You probably know what I mean. Is there even a phoneme for this?

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    Perhaps some people articulate the vowel after SH more as a diphthong (the way Brits say TUES-day, where many Americans say TWOS-day). Is there any US/UK difference in prevalence for the feature being queried? – FumbleFingers Nov 29 '20 at 11:50
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    This is simple assimilation – Decapitated Soul Nov 29 '20 at 12:46
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    @FumbleFingers: Yes, lots of Americans pronounce it assoom /əˈsuːm/, but some pronounce it asjoom /əˈsjuːm/. It's possible the "strange pronunciation" is the second possibility, which is the standard British pronunciation. – Peter Shor Nov 29 '20 at 13:50
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    @PeterShor These sites are a qbit strange. My advanced theoretical physics questions are generally butchered by a guy working in business software or other wannabes, while a simple English musing attracts top notch M.I.T. professors. – user399018 Nov 29 '20 at 16:29
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    Do you mean a “sh” sound like that in assure and passion? – Lawrence Nov 29 '20 at 17:56

Brief answer

Asyoom is sometimes pronounced ASHOOM in some accents because there's a tendency to assimilate (coalesce) ‹S› with the following ‹Y› to a ‹SH› sound. The same thing happens in bless you when pronounced quickly. Another common example is whatcha (what + you).


'Assimilation' is what causes all these changes. It's a process which makes nearby sounds more similar (opposite: dissimilation e.g. colonel pronounced kernel).

There are place assimilation, voicing assimilation and assimilation of manner.

  • In assimilation of place, one of two adjacent sounds changes its place of articulation in order to make it more similar to the other sound, for example, ten pies is usually pronounced te[m]pies in fast (sometimes normal) speech (the place of articulation of the n changes).
  • In voicing assimilation, one of the two adjacent sounds changes its voicing. For example, the B in absorb changes to a P when the suffix -tion is appended: absorption.
  • In assimilation of manner, one sound changes its manner of articulation to become similar in manner to a neighbouring sound. For example, that side is sometimes pronounced [ðæs saɪd]; the plosive /t/ changes its manner of articulation and becomes a fricative.

Pronunciation of ASSUME as ASHOOM

It's an example of coalescent assimilation. In this type of assimilation, two adjacent sounds are merged/coalesced to form a new sound. The following sounds often merge and make new sounds:

  • [s] + [j] → [ʃ]: Mission, assure, sexual etc
  • [z] + [j] → [ʒ]: Vision, treasure, usual, azure etc
  • [t] + [j] → [t͡ʃ]: bet you (betcha), what you (whatcha) etc
  • [d] + [j] → [d͡ʒ]: did you (didja), would you etc

Assume is pronounced [əˈsjuːm] in most British and Australian accents. If you check dictionaries, you will find [əˈsjuːm] for British and [əˈsuːm] (without the /j/) for American pronunciation1 (therefore it may not be common in American accents). However, some people—mostly British and Australians—assimilate the [s] with the following [j] and pronounce it something like [əˈʃuːm].

There are lots of other interesting examples—mostly historical—that illustrate the process. Some of them are:

  • The prefix in the word impossible is in- but has been assimilated to an m because of the following /p/. N often assimilates to /m/ before /p m b/ etc
  • Most people (including me) pronounce the and in 'bread and butter' and 'bits and bobs' as if it were an m in anticipation of the following sound
    • bread[əm]butter
    • bits[əm]bobs
  • Bless you being pronounced with [ʃ]
  • Tune is usually pronounced [t͡ʃuːn] (CHOON) in most varieties of British English
  • Sure and sugar
  • Some people pronounce handbag [ˈhæmbæɡ]: the first process involved in this case is simply the elision of the [d] and then the assimilation of n and b to m.
  • Have to pronounced hafta

/s/ is the 's' in sin
/j/ the 'y' sound in you
/ʃ/ is the 'sh' in ship.
/ʒ/ in genre
/t͡ʃ/ in church.
/d͡ʒ/ in judge.

1: "In many accents of English, /sj/ at the start of a syllable has been simplified to /s/. This simplification has progressed further in North American English than in British English"

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    The one that nails it for me is Bless you! Which until I read this I was blissfully unaware that I would always "assimilate" down to /ʃ/ (the mouth knows what it's doing, even if the brain doesn't! :) – FumbleFingers Nov 29 '20 at 15:52
  • The /sj/ to [ʃ] is probably quite old: Norwegian Language Blog blogs.transparent.com/norwegian/sj-vs-kj The “sj” sound is almost (but not quite exactly) the same as the English “sh” sound. [...] the Norwegian “sj” seems to be a softer sound than the English “sh.”-- ”SJ”: sjokk (shock), sjelden (seldom) ,sjalu (jealous), sjanse (chance), sjuk (sick), sjåvinisme (chauvinism) Notice the cognates and the different ways the same words start in English (ch, j, sh)- – Greybeard Nov 29 '20 at 19:48
  • Assume is pronounced [əˈsuːm] in General American English, not [əˈsjuːm]. IIRC, GAE is more likely to drop yods where other dialects coalesce them. – wjandrea Nov 29 '20 at 20:33
  • I agree a native BrE speaker pronounces [t͡ʃuːn], but claiming that sounds like CHOON is completely wrong. The ch pronunciation sounds like a joke version of some (probably poorly educated) minority group's pronunciation - in the same not-really-funny category as things like "soshul meeja or "lora norda". – alephzero Nov 29 '20 at 21:54
  • @alephzero: I wrote CHOON for those who don't understand IPA. :) – Decapitated Soul Nov 30 '20 at 3:36

As a Brit, I would never ever say [əˈsuːm]. This is strictly a North American pronunciation. I would say [əˈsjuːm] in careful speech, but this may well become [əˈʃuːm] in rapid speech. There is nothing strange about this.

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