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 ¹  before the Lamb. Each ²  of them had a harp and golden bowls full of incense (which are the prayers of the saints). ³ 

I also heard a sound ¹  coming out of heaven like the sound of many waters and like the sound of loud thunder. Now ²  the sound I heard was like that made by harpists playing their harps,

Then ¹  I saw something like a sea of glass ²  mixed with fire, and those who had conquered ³  the beast and his image and the number of his name. They were standing ⁴  by ⁵  the sea of glass, holding harps given to them by God. ⁶