Roosters are happiest when they have hens to watch, mate, and boss around. They don't need to do all three at once or all the time. They are capable of entertaining themselves, much as dogs do when left to their own devices.
The one single thing that keeps a rooster content while eliminating...
And do you respond each and every time to this "song"? Chickens are among many animals that quickly learn cause/effect connections. In other words, There's a chance you're being played.