Formant distortion after codecs for Arabic

In this work, we present results on the effect of wellknown mixed excitation linear prediction (MELP) and code-excited linear prediction (CELP) coders on the formants of Arabic sounds. The study shows, firstly, the spectral distortion of different Arabic phonemes due to mentioned coders. It was found that MELP1200 coder results in largest distortion. The coders effect on vowel formants are then investigated. The experiments show that the first formant of a vowel, on the average, suffers a frequency shift in the order of 50 Hz from its original value. Also, the amplitude distortion of the vowel formants due to Melp1200 coder was the highest, compared to the distortion of the other coders. Vowel formants have a shift which may exceed one critical band below or above its reference value.