Why "sh" pronunciation in "sugar"?

[Donald M Lance]

on 5/7/02 5:21 PM, Douglas G. Wilson at douglas at NB.NET wrote:

>> Today a student asked me why "sugar" and "sure" are pronounced with
>> "sh" (vs. "super" with "s"). Would anyone know?
>
> I shurely wouldn't. But here are my puerile observations anyway.
>
> The palatalization /s(j)u/ > /S(j)u/ is quite common in unstressed
> syllables: "issue", "tissue", "fissure", "censure", "pressure",
> "Assurbanipal"/"Ashurbanipal" (?), etc.
>
> Similar change in stressed syllables is more unconventional; it occurs in
> the 'special cases' "sugar", "sure" ... and in derivatives: "sugary",
> surely", but also "assurance" (but not "assume" or "assurgency").
>
> Offhand I can think of one word -- "sumac" -- where the stressed syllable
> can go either way ("soo-mack" or "shoo-mack").
>
> -- Doug Wilson
>
Since sure, and sugar begin with s-, the assimilation with the palatal
on-glide of the (original) "long u" is (historically) complete, and the
syllable-final consonant "shortens" the remaining -u- sound.  In words like
'visual' and 'tissue', if the syllable boundary I(low energy point) falls
before the on-gline, the apical (tongue tip) fricative may not be
palatalized (or may be only partially palatalized).  If the fricative is
fully palatalized, there is much less likely to be a hint of the yod
on-glide.
DMLance