Eric Christopherson, On 03/09/2013 02:30:
> Likewise there are some colloquial nouns ending in -/o/ here in the
> US, but I tend to think that suffix is more productive at least in
> Australia

Rampant -o is indeed Australian. In Britain -o is mostly restricted to proper names. E.g. an Eric could be _Ez_, _Ezzie_, _Ezzo_, but, say, a book could be a _bookie_ but not a _booko_. (Whereas _Ezzie_ can be not only a nickname but also a diminutive, _Ezzo_ can only be a nickname. (I answer to _Andy_ as a diminutive but not as a nickname.))

> (e.g. _arvo_ "afternoon" -- which additionally shows a voicing, as in
> _Aussie_, which has always puzzled me a little).

It's both puzzling and regular. E.g. _hospital> > _hozzie_, mosquito > _mozzie_. I theorize that in lexical forms the fricative lacks the phonological ingredient of sharpness, so is /z, v/ etc. A blanket phonological rule adds phonological sharpness to the initial obstruent in tautosyllabic clusters in sentence forms (-- actually, not only tautosyllabic but also in the same minimal phonological word, i.e. not separated by a phonological word boundary). When the lexical form is truncated so that there is no longer a tautosyllabic cluster, the sharpening rule fails to apply. So, for example, the lexical entry for _afternoon_ specifies /vd/. That appears in sentence phonology as /fd/ by the sharpening rule. The lexical form truncates to /v/, to which the sharpening rule doesn't apply.