Almost anything that makes a noise has been used for signaling. Cirus, an ancient Persian ruler, established lines of signal towers. At each one. people with powerful voices shouted a message to the next tower, and in this way. news and information was passed on through the kingdom. A kind of drum talk is still used in Central Africa today, although few who are not natives have been able to understand it. The sender u a drum that can produce a high or low tone. Because the local dialect alternates in these tones, the sender is able to simulate speech with the drums.