Three letters Alif ا Waw وْ and Ya يْ which are described by the Arabic grammarians as weak or irregular letters (hurfu al illah), they function as weak vowel (letters of Madd or long vowel) Their primary function is to stretch (lengthen) the sound of a letter having short vowel. Letter Alif ا corresponds to Fat’hah ﹷ ; letter Waw وْ corresponds to Dammah ﹹ and letter Ya يْ corresponds to Kasrah ﹻ . When weak letters are used as lengtheners, and they do not admit any vowel sound. In most cases, the duration of long vowel letters (Huroofe-Maddah Asli Madd) is equal to that of two measures of harakah (duration) or one measure of Alif ا.
Maddah Alif أَلِفٌ مَمْدودَةٌ
As a general rule, when a letter with a Fat’hah ﹷ and next letter is Alif ا, then the sound of Fat’hah and Alif is stretched by two measures of harakah. “aa” , (compare the sound of this exercise with lesson 5 which measures as a single harakah)
Note: In this lesson, letter Alif ا is a true Alif (Madd) . If anytime the letter Alif ا appears with vowels or sukoon اَ اْ أ , this is not a true Alif but it is letter ء Hamza. Letter Alif appears always empty and never the first letter in a word, It may come with Madd آ sign (lesson 23) and always comes after another letter, whereas the letter Hamza may come as the first letter in a word.