To be honest I had never thought of this until, well today, when I decided to google it.
link to (islam QA if it works.)
Imaam Abu Taalib al-Makki (may Allaah have mercy on him) said in his book: one of the things that they have innovated is modulation (varying the tone) in the adhaan, which is a kind of exaggeration and overstepping the mark. One of the muezzins said to Ibn ‘Umar, “I love you for the sake of Allaah,” and he replied, “But I hate you for the sake of Allaah.” He asked, “Why, O Abu ‘Abd al-Rahmaan?” He said, “Because you exaggerate in your adhaan, and you accept payment for it.”
So I went on youtube and had a look at quite a few. Most do the vibration/tone change to beautify the adhan. I don't know if I would class it as singing, but it sure isn't the same as speaking the adhan.
link to (islam QA if it works.)
Quote:
Imaam Abu Taalib al-Makki (may Allaah have mercy on him) said in his book: one of the things that they have innovated is modulation (varying the tone) in the adhaan, which is a kind of exaggeration and overstepping the mark. One of the muezzins said to Ibn ‘Umar, “I love you for the sake of Allaah,” and he replied, “But I hate you for the sake of Allaah.” He asked, “Why, O Abu ‘Abd al-Rahmaan?” He said, “Because you exaggerate in your adhaan, and you accept payment for it.”