Production and perception of Persian geminate stops at three speaking rates

Abstract

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.