This study deals with the co-variation of speech clarity and coarticulatory patterns. Two experiments were conducted to investigate the influence of two parameters on coarticulation, the speech style (formal vs. non formal) and the prosodic position (stressed vs. unstressed syllable). The speech material was composed of four word lists varying CV syllable contexts with pharyngealized /t d s / vs. non- pharyngealized consonants /t d s / in Modern standard Arabic and dialectal Arabic. Acoustic and EMA materials were analyzed. The results revealed evident relationship between speech clarity and coarticulation: more coarticulation in formal speech (MSA) and under stressed syllable.