Are there conditions and controls for selecting the muezzin, or is the bad, annoying voice of the muezzin acceptable to the people of the area under the pretext of serving the mosque and his proficiency?

The muezzin's voice should be pleasant, and this is a recommended, not an obligatory, quality, just as the jurists disliked embellishment and melodious chanting in the adhan. If someone with a more beautiful voice is available, he should perform the adhan, and the remuneration should be allocated to the mosque's affairs. If no one else is available, there is no harm in him undertaking the adhan. Raising his voice is recommended, and if his voice is pleasant, it does not invalidate the adhan.