“And I heard a sound out of heaven as the sound of many waters and as the sound of loud thunder; and the sound that I heard was as of singers who accompany themselves on the harp playing on their harps.

Revelation 14:2,

It is no wonder that John, upon hearing 144,000 voices joined in one melodious chorus, is reminded of roaring waterfalls and pealing thunderclaps. How pleasant that clear harplike accompaniment! (Psalm 81:2)