Laryngeal realism and the voicing contrast in Khuzestani Arabic stops

In laryngeal realism (LR), laryngeal specification of stops is explained by direct maps of cues (e.g. VOT) onto privative phonological laryngeal features [voice] or [spread glottis]. Phonetic realization of the segments and speakers' 'control' (e.g. the degree of intervocalic voicing and speech rate manipulation effects on VOT duration) are used as diagnostics of phonological specification. Similar to some Arabic vernacular dialects (e.g. Qatari Arabic), Khuzestani Arabic in Iran presents a case where three voiced stops /b d g/ are in contrast with voiceless stops /p t k/, but two voiceless guttural plosives /ts q/ have no voiced homorganic counterparts. In this paper we examine the phonetic realization of voicing in these stops at word-initial and intervocalic position, as well as the effects of speech rate manipulation on VOT and closure voicing. The data came from 12 native speakers recorded in Khorramshahr, Iran. Our findings suggest an over-specified voicing system in this Arabic variety. We found that voiced /b d g/ were produced with voicing lead in initial position and complete closure voicing word medially, voiceless /p t k/ had long lag VOT, while guttural /ts q/ had short lag VOT. Speech rate manipulation revealed that only duration of (pre)voicing and duration of aspiration increased in slower speech. Also, f0, F1, and F2 were measured at vowel onset to evaluate the glottal state in production of stops. The results support the predictions of LR that voiced stops are specified by [voice], voiceless stops are [sg], while gutturals lack underlying specification for voice