The linguistic sounds are influenced by each other during the performance. Because a person by nature tends to facilitate and facilitate and shorten the muscular effort he exerts when pronouncing, so he resorts to changing other sounds, to achieve the phonological harmony of performance. These effects give rise to acoustic phenomena , like: voiced, diphthong, substitution, vowel, etc. These effects are either from within the word itself or from the proximity of other words, and since the Quran was the first Arabic book, its readings were full of these phonemic phenomena. The phenomena of voiced and diphthong which we will address in this paper.