Ibn Umar reported: When the Muslims came to Medina, they gathered and sought to know the time of prayer but no one summoned them. One day they discussed the matter, and some of them said: Use something like the bell of the Christians and some of them said: Use horn like that of the Jews. Umar said: Why may not a be appointed who should call (people) to prayer? The Messenger of Allah (may peace be upon him) said: O Bilal, get up and summon (the people) to prayer.
BUKHARI, Volume 1, Book 11, Number 578:
Narrated Ibn 'Umar:
When the Muslims arrived at Medina, they used to assemble for the prayer, and used to guess the time for it. During those days, the practice of Adhan for the prayers had not been introduced yet. Once they discussed this problem regarding the call for prayer. Some people suggested the use of a bell like the Christians, others proposed a trumpet like the horn used by the Jews, but 'Umar was the first to suggest that a man should call (the people) for the prayer; so Allah's Apostle ordered Bilal to get up and pronounce the Adhan for prayers.
BUKHARI, Volume 1, Book 11, Number 577:
The people mentioned the fire and the bell (they suggested those as signals to indicate the starting of prayers), and by that they mentioned the Jews and the Christians. Then Bilal was ordered to pronounce Adhan for the prayer by saying its wordings twice, and for the Iqama (the call for the actual standing for the prayers in rows) by saying its wordings once. (Iqama is pronounced when the people are ready for the prayer).
Adzan (dalam Islam) adalah bertujuan menyaingi umat kapir dengan cara teriak sekeras2nya pakai toa dan speaker di empat penjuru supaya tampil beda dengan Christian dengan bellnya serta jews dgn trumpet . . .
atau dalam hal ini islam iri dengan tata cara ibadat kapir dan menyainginya sehingga terciptalah polusi udara apabila islam mengumandangkan adzan.