In reference to the Morrocan delicacy cous cous, Americans generally say /kus kus/ or perhaps [kʉs kʉs]. But Nigella Lawson (UK) of Nigella Bites fame says [kʊs kʊs] (rhymes with “wuss”). I listened to her several times just to be sure.
I couldn’t tell if it’s a phonetic quirk if there was a phonemic lax /ʊ/, so I went to the online OED and sure enough they give both UK /kʊs kʊs/ and original French /kusku/ (from French couscouse < Arabic kuskus).
I found this very unusual, because normally in the US, the lax /ʊ/ is a phoneme restricted to "native words," but this is a case where original Franco-Arabic /u/ changed to /ʊ/ (probably because of the closed syllable).
However in the US, the phoneme has remained /u/ or phonetically /ʉ/ depending on the speaker. Gernerally speaking non-English /u/ remains /u/ (cf. Peru, mousse, moussaka).
Now I’m curious, so I’m looking up some /u/ borrowings. So far I have
moussaka (Greek dish) = /mʊsaka/ or /musaka/ in OED, but usually /musaka/ in the US
mousse (French) = /mus/ only in OED
douche (French) = /duʃ/ only in OED
culinary (French+ Latinate) = /kjulɪnəri/ (OED) but /kə/, /ku/ or /kʊ/ in US; the /kj/ "ky" survives only in careful American speech
tutti frutti (Italian) = /tuti fruti/ (OED)
It looks there's variation, but French and Italian /u/'s may be safer.
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