Benjamin B Hansen

... Kristiina Rosser, Jenny Söderman, Helena Tiainen, Asta and Kari Leppänen, and the wonderful people of the Finnish Language School ... 19th century, histori-cal linguists have offered explanations of sound change based on phonetic patterns of production and perception. ...

A number of languages have independently developed a pattern of vowel-length neutralisation according to which a vowel after a vocoid must be long. It is proposed that this pattern arises from the inherent acoustic ambiguity of such sequences, which are realised with a diphthongal transition from one formant pattern to the next, with no clear boundary between the two. Neutralisation in vocoid sequences originates from listeners' difficulties in determining the duration of vowels in this context. Lengthening of the second vocoid arises when listeners attribute some of the transition duration to that segment. The phonetic bases of this account are supported by three experiments with Finnish speakers. A production study shows that speakers treat the transition as belonging in part to the realisation of the postvocoid vowel. Two perception studies show that increasing the duration of the transition increases the probability of such a vowel being identified as long.

An experiment was designed to determine whether the geminate/singleton category distinction is maintained at fast speaking rates in Persian. Three speakers of Tehrani Persian read test words containing [t,t:,d,d:] in carrier sentences at three speaking rates. The categories do not overlap within a given speaking rate, but the fastest geminates do overlap the normal-rate singletons, implying that the listener must take speaking rate into account in order to perceive the category distinction. The ratio of the consonant closure to the preceding vowel (C/V) is not a useful rate-independent parameter for describing the geminate/singleton boundary in Persian since in Persian the vowel preceding a geminate is slightly longer. However, it was found that the marginal consonant closure (above a minimum closure of about 20 ms) maintains a fixed proportion of the average syllable duration, regardless of rate. This fixed proportion is distinct for geminates and singletons, and so may be used as a single rate-independent parameter for defining the category distinction. Perception tests on natural sentences showed that the distinction is perceptible at each of the three speaking rates. The perceptual response to manipulation of the closure durations indicated that, besides duration, additional cues to the distinction are present.

Across languages, there is a tendency to avoid length contrasts in the most vowel-like consonant classes, such as glides or laryngeals. Such gaps could arise from the difficulty of determining where the boundary between vowel and consonant lies when the transition between them is gradual. This claim is tested in Persian (Farsi), which has length contrasts in all classes of consonants, including glides and laryngeals. Persian geminates were compared to singletons in three different speaking rates and seven different consonant classes. Geminates were found to have longer constriction intervals than singletons, and this length effect interacted with both speaking rate and manner of articulation. In one of two perception experiments, Persian speakers identified consonants as geminate or singleton in stimuli in which the constriction duration was systematically varied. The perceptual boundary between geminates and singletons was most sharply defined for obstruents and least so for laryng...