Vowel length may also have arisen as an allophonic quality of a single vowel phoneme, which may have then become split in two phonemes. For example, the Australian English phoneme was created by the incomplete application of a rule extending before certain voiced consonants, a phenomenon known as the bad–lad split. An alternative pathway to the phonemicization of allophonic vowel length is the shift of a vowel of a formerly-different quality to become the short counterpart of a vowel pair. That too is exemplified by Australian English, whose contrast between (as in "duck") and (as in "dark") was brought about by a lowering of the earlier .