Aha, I asked a lot about these horns when I was over there. What I was told is that they are old hunting horns left behind by French colonizers. The hunters may have traded them with the villagers. I tried to buy one over there but I was told that most villages would only have one if they even had one. I saw standard whistles being used in much the same way over there.
I had a look on Ebay and in various places for one.
http://cgi.ebay.fr/trompe-de-chasse-/22 ... 336bec42bb
I reckon something like this would sound similar. I'd love to get one, let it rip during Gbada!
An awful idea came into my head during a fete once:
I could introduce the Vuvuzela to Guinea
For those of you who don't know what a Vuvuzela is, it's an incredibly loud plastic horn which is popular at South African football matches. It's based on a traditional type of horn. They had to ban them from the Euro 2012 cup because of the insane noise they make, distracting players and causing hearing damage to fans.
Anyways, it occurred to me that they would probably catch on like wildfire in Guinea and I'd be singlehandedly responsible for ruining Guinean music.