It's fortunate that I don't mind the sound of roosters crowing, I much prefer hearing them than many other sounds coming from my or my neighbors' yards. Sounds like throbbing bass recordings (sorry, I can't call them music) that resonate through the house foundation, a chained dog with a...
Try a long soak in simmering broth...
But seriously, I've heard of methods others have mentioned, usually with roosters they're trying to keep quiet because they're in a residential neighborhood where they aren't allowed to keep them. But IMO, they're not ideal conditions for long-term chicken...