Why does hadero play the sound of an opera singer warming up? what does this short musical clip reveal to the audiance about music ?

Actually that wasn't the sound " of opera singer warming up". What it actually was the slowed down sound of a bird singing and this was intentionally done to trick the audience. This was done in order to illustrate that there is music in nature and that the music is actually everywhere.

That she has to go to a later concert and tour, but there will be new songs out by billie eilish by then