Divine mouthpiece.

We know that sound spreads in all directions and therefore weakens very quickly; with the help of a horn, it can be directed mainly in one direction, along which it is desirable to transmit sound with greater power. They worked on the mouthpiece for hundreds of years, but they came to the conclusion that the simplest voice was the best. It can be easily made from the folder **. Sew or glue a tube with a length of 2 m from a smooth folder so that one end is 15–20 cm in diameter and the other end is 3 cm, that is, a tube of conical shape. Glue a small funnel to the narrow end of the tube. The walls of the horn will not allow the sound to dissipate, and from this its strength does not weaken noticeably for a very far distance. If the pipe is 2 m long and is well glued together, then you can talk at a distance of 1 km (1000 m), and even during quiet weather, even at night, even further. The voice coming from the horn, especially when you can not see where and who says, has something supernatural, magical, and therefore it is clear that even in our enlightened time superstitious people come from him to fear and awe.

** It is possible from the glued wallpaper glue in several layers of newspaper sheets or paper wallpaper. - Approx. ed.
Science and life
If I'm not mistaken, this shout was described in the book about Robert Wood.