This paragraph can be divided into two sections, with each section in turn having multiple subsections.
Revelation 19:1–5 gives us three heavenly summonses to praise God:
the voice of the great multitude (Revelation 19:1–3)
the voice of the twenty-four elders and four living creatures (Revelation 19:4)
a single voice from the throne (Revelation 19:5)
Revelation 19:6–10 shows us a creation-wide response to the heavenly summons:
first from the great multitude (Revelation 19:6–8)
then a confirmation that the joyful response from earth is indeed accurate and legitimate (Revelation 19:9–10)
1 After this I heard what seemed to be the loud voice of a great multitude in heaven, crying out, “Hallelujah! Salvation and glory and power belong to our God,