Phonologyical voicing contrasts in Australian Aboriginal languages

It is widely known that the phonological systems of Australian Aboriginal languages show many similarities right across the continent. One characteristic of these systems that has been often reported is the lack in most languages of a phonological contrast between voiced and voiceless stops. This paper is an investigation of the occurrence of such a contrast in a number of widely scattered languages. It will be shown that, in a number of instances, phonological voicing is a recent historical development in the languages which have it, and the contrast has been subject to linguistic diffusion in one of the areas where it is found. Certain generalisations about the types of phonological voicing contrasts that tend to be found in Australia are also advanced.