Durational contrast in gemination and informativity

Recent studies in Message Oriented Phonology (MOP) have provided increasing evidence that informativity plays a non-trivial role in linguistic behavior. This paper provides a case study of MOP focusing on the durational contrast of singleton and geminate consonants in spoken Japanese. In modern Japanese, short consonants (singletons) and long consonants (geminates) are lexically contrastive, and the durational properties of these consonants are affected by a variety of factors. This provides a useful test of the assumptions of MOP. Based on the assumption that the higher the informativity, the more robustly the contrast is phonetically implemented, this study examines the hypothesis that the durations of singletons and geminates increase or decrease according to the informativity of their durational contrast. The study confirms that (i) the distribution of singletons and geminates is affected by the manner of articulation and positional differences (morpheme-initial, medial, and final); (ii) the distributional differences follow from the informativity of contrasts as represented by Shannon's entropy; and (iii) the durational contrast is enhanced by the presence or absence of a minimal pair.