Acoustic Correlates of Emphatic Sounds in Palestinian Arabic-speaking Persons with Aphasia

Abstract

Objective:The aim of this study was to examine the acoustic characteristics of the emphatic sounds as produced by Palestinian Arabic-speaking persons diagnosed with Broca's aphasia as compared to normal speakers. Method: The acoustic correlates of emphasis in Palestinian Arabic using measurements of voice onset time (VOT), frequency values of F1 and F2 formants, and duration of vowel were investigated. Four subjects diagnosed with Broca's aphasia and four normal speakers residing in the West Bank participated in this study. The emphatic stop /t¯/ and its plain counterpart /t/ in initial positions presented in monosyllabic words were investigated. The target stops were followed immediately by the vowels /a/, /u/, and /i/. The speech samples were analyzed using PRAAT and Phono lab speech analysis software,. F1 and F2 formants were measured and compared with the data in the literature. Results: The acoustic measurements of the target vowels demonstrated an increase in F1 and a decrease in F2 formant in case of emphatic sounds compared to the plain one. Lowering of F2 formant was found to be a reliable acoustic cue of emphatic sounds. However, F2 formant was generally higher among subjects with Broca's aphasia compared to the control group. The results also revealed that subjects with Broca's aphasia were unable to maintain the acoustic distinction between the emphatic sounds and their plain counterparts. Conclusion: The VOT value of the emphatic voiceless stop /t¯/ was significantly shorter than that of its plain counterpart /t/ as demonstrated by both the normal speakers and the subjects with Broca's aphasia. The articulatory complexity of the emphatic sounds and therefore the deviated patterns in subjects with Broca's aphasia might suggest motor programming and motor planning deficits.