The Messenger of Allah ﷺ had two Mu'adhdhins, Bilal and 'Abdullah b. Umm Maktum, who (latter) was blind.  

كَانَ لِرَسُولِ اللَّهِ ﷺ مُؤَذِّنَانِ بِلاَلٌ وَابْنُ أُمِّ مَكْتُومٍ الأَعْمَى  

This hadith has been narrated on the authority of 'A'isha by another chain of transmitters.  

عَنْ عَائِشَةَ مِثْلَهُ