Almost anything that makes a noise has been used for signaling. Cyrus ,an ancient Persian ruler, estabished 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 usad in central Africa today, althoung few who are not natives have been able to understand it. The sender uses 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.