Even inanimate things, like the flute or the harp, may give out sounds, but if there is no difference in the notes, how can the tune that is played on the flute or the harp be told?

When He took it, the four living creatures and the twenty-four elders fell down before the Lamb, each with a harp, and golden bowls that were full of incense, which represent the prayers of God's people.

And I heard a sound from heaven like the roar of great waters and the rumbling of loud thunders. The sound that I heard was like that of harpists playing on their harps.

Then I saw something that looked like a sea of glass mixed with fire, and standing upon the sea of glass were those who had conquered the wild beast, his statue, and the number representing his name; and they had harps that God had given them.