I'm going to take a minute to give my rant of this annoying instrument, from an in-stadium perspective (we've somewhat learned to tune them out when watching a game on TV, but it's much different in the stadium).
I've been to many soccer games around the world, and one of the aspects of the games I enjoy most are the fans: how they dress, celebrate, cheer, chant, sing. At this World Cup, any attempt at song by fans is almost completely killed by the sound of the horns, which, in my opinion, don't add any flavor to the atmosphere.
We've been to four games this week, and we've seen fans of the participating countries representing their colors in good numbers. We can see them jump around, pump their fists, wave their flags. But we can't hear them, even if they are only one section away. It's unlike any of the recent World Cups, where it felt like the section could be heard from across the stadium.
You're left hoarse after a game, as much for the attempted cheering as by trying to talk to the person next to you. I understand it's a popular way to enjoy a game down here. I just wish that for even short stretches of a game they would stop to allow the visiting fans to enjoy the game as they know how.