text: 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 .
  Estonian, a Finnic language, has a rare phenomenon in which allophonic length variation has become phonemic after the deletion of the suffixes causing the allophony. Estonian had already inherited two vowel lengths from Proto-Finnic, but a third one was then introduced. For example, the Finnic imperative marker *-k caused the preceding vowels to be articulated shorter. After the deletion of the marker, the allophonic length became phonemic, as shown in the example above.
  Notations
  Latin alphabet
  IPA
  In the International Phonetic Alphabet the sign  (not a colon, but two triangles facing each other in an hourglass shape; Unicode ) is used for both vowel and consonant length. This may be doubled for an extra-long sound, or the top half () may be used to indicate that a sound is "half long". A breve is used to mark an extra-short vowel or consonant.
  Estonian has a three-way phonemic contrast:
  saada  "to get" (overlong)
  saada  "send!" (long)
  sada  "hundred" (short)
  Although not phonemic, a half-long distinction can also be illustrated in certain accents of English:
  bead
  beat
  bid
  bit