Attachments :
A question for Urban:
Ladefoged & Maddieson (following Lindblad) describe two variant articulations of Swedish [ɧ]. One (actually second in their order of exposition) is very similar to what you described in your posting on "phonetic curiosities". The other is defined as a strongly rounded labiodental velar or velarised voiceless fricative. In simpler terms, they describe it more or less as [f] and [x] articulated simultaneously, with strong lip protrusion. There is more detail in the book but I haven't got it with me now and am quoting from memory; I can provide a verbatim quotation if necessary. It appears from the description that in this variant the labiodental articulation is primary and the velar constriction serves to colour to the sound dark. Can you comment on this?
I also wonder if the early Modern English confusion between [f] and [x] (as illustrated by the pronunciation of enough or laugh) did not result from the existence of a similarly complex fricative in English once upon a time. And of course Ukrainian could be another case.