Production and perception of Libyan Arabic vowels

Abstract

This study investigates the production and perception of Libyan Arabic (LA) vowels by native speakers and the relation between these major aspects of speech. The aim was to provide a detailed acoustic and auditory description of the vowels available in the LA inventory and to compare the phonetic features of these vowels with those of other Arabic varieties. A review of the relevant literature showed that the LA dialect has not been investigated experimentally. The small number of studies conducted in the last few decades have been based mainly on impressionistic accounts. This study consists of two main investigations: one concerned with vowel production and the other with vowel perception. In terms of production, the study focused on gathering the data necessary to define the vowel inventory of the dialect and to explore the qualitative and quantitative characteristics of the vowels contained in this inventory. Twenty native speakers of LA were recorded while reading target monosyllabic words in carrier sentences. Acoustic and auditory analyses were used in order to provide a fairly comprehensive and objective description of the vocalic system of LA. The results showed that phonologically short and long Arabic vowels vary significantly in quality as well as quantity; a finding which is increasingly being reported in experimental studies of other Arabic dialects. Short vowels in LA tend to be more centralised than has been reported for other Arabic vowels, especially with regards to short /a/. The study also looked at the effect of voicing in neighbouring consonants and vowel height on vowel duration, and the findings were compared to those of other varieties/languages. The perception part of the study explored the extent to which listeners use the same acoustic cues of length and quality in vowel perception that are evident in their production. This involved the use of continua from synthesised vowels which varied along duration and/or formant frequency dimensions. The continua were randomised and played to 20 native listeners who took part in an identification task. The results show that, when it comes to perception, Arabic listeners still rely mainly on quantity for the distinction between phonologically long and short vowels. That is, when presented with stimuli containing conflicting acoustic cues (formant frequencies that are typical of long vowels but with short duration or formant frequencies that are typical of short vowels but with long duration), listeners reacted consistently to duration rather than formant frequency. The results of both parts of the study provided some understanding of the LA vowel system. The production data allowed for a detailed description of the phonetic characteristics of LA vowels, and the acoustic space that they occupy was compared with those of other Arabic varieties. The perception data showed that production and perception do not always go hand in hand and that primary acoustic cues for the identification of vowels are dialect- and language-specific.