Heaven is a noisy place. There are several ways of describing it. There is the "mighty voice" or "strong voice" (ἰσχυρᾷ φωνῇ), found once in Revelation. Or there are 28 times that John describes a big voice (φωνῇ μεγάλῃ). There are also thunder and lightening, roaring crowds, music and singing.
The picture here is of an abandoned city. There are no people, only evil spirits and vultures. It has become a desolate ruin.
Is this a picture of an actual city or is it figurative. It may be both. Imagine New York City after it has been totally abandoned. It is eerie. Empty buildings as far as you can see.
What caused Babylon the great to be destroyed and abandoned? We are given some clues. In verses 17-18 of this chapter we see the merchants weeping over her:Rev. 18:17-18
". . . for in one hour such great wealth has been laid waste!′ And every shipmaster and every passenger and sailor, and as many as make their living by the sea, stood at a distance, 18 and were crying out as they saw the smoke of her burning.
Whatever happens to her, it appears that her destruction is sudden and the smoke can be seen from a distance.
If the economy and banking system has collapsed, the people could not survive in a large city: The water would not be safe to drink; Without electricity, there would be no heat or light; There would soon be nothing left to eat. Any people who survived would need to leave the city to find food and water. The city would be abandoned.