'Harps' in the Bible

Even inanimate things--flutes or harps, for instance--when yielding a sound, if they make no distinction in the notes, how shall the tune which is played on the flute or the harp be known?

And I heard music from Heaven which resembled the sound of many waters and the roar of loud thunder; and the music which I heard was like that of harpists playing upon their harps.

And I saw what seemed to be a sea of glass mingled with fire, and those who had gained the victory over the Wild Beast and over his statue and the number of his name, standing by the sea of glass and having harps which belonged to God.