Friday is the Holy Day for Muslims. This recording was taken just after sunset on a cold Friday night in Istanbul, in the great and chaotic space between the Hagia Sophia and the Sultan Ahmet Mosque (known to Americans as the Blue Mosque), two of the most amazing religious structures in that part of the world. You can hear three separate Muezzin calling - traditionally each mosque has its own Muezzin, a man who recites the call to prayer 5 times a day from a minaret. Historically, the men who become muezzin were blind, for a couple different reasons i guess; but now sadly and somewhat controversially, they are being replaced by digital recordings.
I'd like to think the Ahmet Mosque and the others are live, through a loudspeaker, but I don't know if they are.