Acoustic parameters of emphasis in Libyan Arabic

Abstract

This study investigates the acoustic implementation of the emphatic consonants in Libyan Arabic (LA) as compared to their non-emphatic counterparts. One aim is to explore how the acoustic patterns in LA compare with those found in other Arabic dialects, especially since this is the first study of its kind in LA. Another aim is to relate these acoustic patterns to the articulation of the emphatics. The acoustic cues that were investigated included the first three formant frequencies in the vowels following plain and emphatic consonants, locus equations, and various vocalic and consonantal duration measurements that have shown to be relevant for the contrast in other varieties of Arabic. Twenty native speakers of LA were recruited for this study and produced randomised target monosyllabic words with initial plain /t d s/ and emphatic /tˁ dˁ sˁ/ in carrier sentences. These consonants were followed by the LA vowels /i: e: I æ:ɛ 0: u: ʊ/. In terms of formant frequency results, emphasis led to an increase in FI and F3 and a decrease in F2; this effect was consistent across all vocalic contexts apart from an F3 decrease for /i:/. The effect of emphasis on formant frequency patterns was more pronounced at the onset of vowels than at their midpoint, particularly for the first two formant frequencies. The magnitude of this effect also depended on vowel quality and quantity. These observations were supported by an auditory analysis of the vowels, which were affected by the backing gesture of emphasis. Locus equations were measured to explore CV coarticulation for both plain and emphatic consonants by the regression analysis of F2 onset and F2 midpoint. In general, the emphatic consonants displayed a lower (flatter) slope and y-intercept than their plain counterparts, suggesting a low F2 onset and C-to-V coarticulatory resistance. In terms of durational measurements, the emphatic /tˁ/ was found to have shorter VOT than the plain [tʰ] which was aspirated. This showed an effect of the pharyngeal constriction on the timing of laryngeal activities and the degree of glottal opening. On the other hand, closure duration and vowel duration were longer for the /tˁ/ than for the /t/ context. Although this seemed to indicate an effect of emphasis, the total duration of CD, VOT and VD was found to be similar for both the plain and emphatic context, suggesting a temporal relationship between these acoustic parameters. This relationship was also found in the fricative context. The intensity and duration difference between /sˁ/ and /s/ were not significant. This study has revealed how the acoustic patterns represented the articulation of the emphatic consonants in LA by assessing the contribution of a combination of acoustic features to the plain-emphatic distinction. The cross-dialectal comparison between LA and other Arabic dialects showed that the acoustic results may suggest that the articulatory correlates of emphasis could vary cross-dialectally.