You'll find what's known as a "horn call" in a lot of operas or pieces of music that tell a story. Horn calls are used to grab people's attentions. In an opera call "Siegfried" (written by Richard Wagner), there's a VERY famous horn call. In the story, this is where the main character, named Siegfried, hears a bird and tries to talk back to it with his horn. He ends up waking up a dragon with the horn call, instead!!