Production of Persian Geminate Stops: Effects of Varying Speaking Rate

Tehrani Persian has a phonological contrast between geminate and singleton consonants. For example, [made] (female) contrasts with [mad:e] (material). An interesting observation has been made by Iranian researchers regarding geminates: for certain words speakers may pronounce geminate consonants as a singletons. Mahootian (1997) states that for native (non-Arabic) words “the geminates in these words are often, if not usually, reduced.” Deyhime (2000) transcribed the pronunciations of 16 speakers of Tehrani Persian and whereas geminated stop consonants in words of Arabic origin are pronounced as geminates by all informants, the geminate stops in native words are pronounced by some of the informants as singletons. For example, the word for “childhood” is pronounced by some informants as [bačegi], and by others as [bač:egi]. Ohala (1981) describes a process by which “mini sound changes” arise from misclassification of segments when a listener fails to decode the phonetic context and thereby opens the way for phonologizing a context-dependent articulation. Lindblom et al. (1995) suggest that the acceptability of an alternate pronunciation is measured in part by its “social value” in addition to its “articulatory complexity” and its “perceptual distinctiveness.” The case of the universally-enforced gemination of stops in Arabic loanwords in Persian could be seen as an instance of social value upholding a canonical pronunciation in the face of a sometimes-ambiguous distinction in real-life speech. This study seeks to identify whether the geminate and singleton categories do in fact overlap at normal and two faster speaking rates. Several studies have sought to determine the acoustic cues for gemination. Lahiri & Hankamer (1988) and Hankamer et al. (1989) studied gemination in Turkish and Bengali, where they detected the presence of secondary cues from perception tests, but could not identify which parameter other than duration actually influenced the perception of gemination. They concluded that closure duration is the single overriding cue for gemination in both Turkish and Bengali. For Italian stops, Pickett et al. (1999) found that a short preceding vowel duration was a secondary cue for gemination, but the stop closure duration cue is strong enough to override it: only when the closure duration was ambiguous between the geminate and singleton categories did the length of the preceding vowel influenced judgments of the geminate/singleton distinction. Pind (1995) found that for Icelandic, the ratio of the consonant to the preceding vowel was the primary cue for gemination and this ratio remains invariant at different rates. He reports the discriminating ratio to be close to 1. Han (1994) reports that for Japanese, a lengthened preceding vowel may be a secondary cue for gemination, but the observation is not supported by a quantitative analysis. The idea that the listener may have to factor out rate-dependent changes has also been the subject of a number of studies. Miller (1981) found that listeners adjust to the speaking rate when using the F1 formant transition duration as a cue to distinguish between /b/ and /w/ in English. She concluded that rate-dependent perceptual effects exist. Pickett et al. (1999) found that perception of the geminate/singleton distinction in Italian is conditioned by the speaking rate, but that a higher order relational measure (the closure duration/preceding vowel duration ratio) remains constant as a discriminator between the geminate and singleton categories. This latter result coincides with Pind’s observation cited above. Kessinger & Blumstein (1997) on the other hand concluded that an adjustment of the category boundary is not necessary to perceive the distinctions between long lag and short lag voice onset time (VOT) in Thai and English or between prevoiced and short lag VOT in French and Thai; a single discriminating value for each distinction may be applied across speaking rates. Finally, Magen & Blumstein (1993) discovered that in Korean, no asymmetry exists in the response of long vs. short vowels to changes in speaking rate: both categories are equally affected by rate.