An instrumental phonetic investigation of timing relations in two-stop consonant clusters in Tripolitanian Libyan Arabic

This study uses acoustic, electropalatographic and laryngographic data to investigate articulatory timing and the timing of voicing of single stops and two-stop consonant clusters in Tripolitanian Libyan Arabic. The theoretical framework which has been adopted in this investigation is based on Articulatory Phonology. An acoustic approach is also employed in this study to measure the duration of segments and overlap in clusters. Another objective of this research is to determine whether syllable position, place of articulation, including articulation sequence, the morphological structure, gender of the speaker and articulation rate will have an influence on the gestural coordination and the timing of voicing of Tripolitanian Libyan Arabic stops. Fourteen native speakers of Tripolitanian Libyan Arabic produced fifty-eight mostly monosyllabic words that contain seven syllable-initial single stops, seven syllable-final single stops, twenty-seven syllable-initial two-stop clusters and seventeen syllable-final two-stop clusters in normal, fast and slow articulation rate. One speaker was recorded using Electropalatography and Laryngography. Measurements include duration of the hold phase of the stops, the duration of overlap/delay between two adjacent consonantal closures, the timing and duration of the voicing during the hold phase and the duration of VOT. Statistical results show significant influence of syllable position, place of articulation, gender and speaking rate on the gestural coordination of two-stop clusters. In syllable-initial position, the pattern of coordination is characterised by an overlap between the two consonantal closures or by a short delay as a result of the release of the first stop. In syllable-final position, the pattern of coordination of two consonantal gestures is marked by a less cohesive coordination leading to the existence of an epenthetic vowel. These patterns of coordination varied as a function of place of articulation, gender of the speaker and the rate of articulation. Clusters with lingual stops are less overlapped compared to clusters containing bilabial stops. Male speakers produced longer hold phase durations and longer inter-consonantal intervals in comparison with female speakers. While in faster articulation rates the two consonantal gestures were reduced in duration and exhibited more gestural overlap, slow articulation rate resulted in the opposite outcome. Results of the influences of articulation sequence and morphological structure of the cluster were less evident. Finally, the duration of voice onset time and the timing and duration of voicing during the hold phase varied as a function of syllable position, place of articulation and articulation rate, with more voicing in syllable-final single stops than syllable-initial and an increase in voicing by the increase in articulation rate, and the opposite pattern is evident in slow articulation rate. The duration of VOT becomes longer as the place of articulation moves back and shorter when the articulation rate is increased. In slow speaking rate, VOT is longer.