Is it forbidden to intone the Adhan melodically and to stretch the vowels?

It is not permissible to chant the Adhan or to embellish it with musicality. This act is considered either disliked (makruh) or forbidden (haram), unless it alters the meaning, in which case it becomes Haram. It is recommended for the Adhan to be recited at a moderate pace, and stretching or embellishing it is disliked due to the transgression involved in the Adhan, and because it renders it incomprehensible. Some scholars have even considered it an reprehensible innovation (bid'ah mustahjanah). Embellishing (tatreeb) means to break up the voice and make it tremble, and it can be forbidden if it becomes excessive. It is recommended for the muezzin to have a pleasant and loud voice, and to reverberate it. A harsh, terrifying voice is disliked, as are embellishment (tatreeb) and mournful tones (tahzeen) if they are not excessive; otherwise, they are forbidden. Melodizing (talheen) that alters the meaning invalidates the Adhan, while that which does not alter the meaning is disliked.