It is similar for lifeless things that make a sound, like a flute or harp. Unless they make a distinction in the notes, how can what is played on the flute or harp be understood?

and when he had taken the scroll, the four living creatures and the twenty-four elders threw themselves to the ground before the Lamb. Each of them had a harp and golden bowls full of incense (which are the prayers of the saints).

I also heard a sound coming out of heaven like the sound of many waters and like the sound of loud thunder. Now the sound I heard was like that made by harpists playing their harps,

Then I saw something like a sea of glass mixed with fire, and those who had conquered the beast and his image and the number of his name. They were standing by the sea of glass, holding harps given to them by God.