Conch shells can be used as horns but the person must make a buzzing sound with their lips in order to have it work. Just blowing into the conch shell won't work. The buzzing sound made from a person's lips gets amplified by the conch shell, much like a bugle horn.
The technique for playing a conch shell is very similar to how one would play a trumpet or bugle. The lips must be pressed tightly together so a strong buzzing noise can be created. Some conch shells are actually sold with bronze mouthpieces fitted into them to create a better sound.
Conch shells can be easily turned into instruments. Throughout the Caribbean, conch shells can be found on the beach or by diving for them. If someone lives far away from the Caribbean, besides buying them online, one can use other types of shells for the same purpose, like Whelk shells, which can be found in Massachusetts. As long as the shell is 6 inches long, it will work. The sound of the shell only changes its pitch depending on the size, so bigger shells will have a deeper pitch. Using a hacksaw or some kind of metal-cutting blade, the mouthpiece can be cut from the shell. The hole should have the diameter of a U.S. dime. A piece of sandpaper can also be used to smooth out the mouthpiece, so it's safe to press lips against. There will also be a structure in sight once the hole is cut. A nail can then be used to break it off, which will allow air to flow through the shell and amplify the sound from the lips.