d cosmic rays are not very good to human physiology and therefore aren't available for us to use for communication at this point. Because of the problems with very low and very high frequencies, we primarily use the middle of the electromagnetic spectrum for communication-the radio, microwave, infrared, and visible light portions of the spectrum. We do this by modulating the amplitudes, frequencies, and phases of the electromagnetic waves. Bandwidth is actually a measure of the difference between the lowest and highest frequencies being carried. Each of the communications bands offers differing amounts of bandwidth, based on the range of frequencies they cover. The higher up in the spectrum, the greater the range of frequencies involved. However, this is largely a licensing issue; the spectrum is controlled and allocated by government agencies, such as the Federal Communications Commission (FCC; www.fcc.gov), Canadian Radio-television and Telecommunications Commission (CRTC; WWW. crtc.gc.ca), and International Telecommunication Union (ITU; www.itu.int). Infrasound and the Animal World The universe is full of infrasound, the frequencies below the range of human hearing. Earthquakes, wind, thunder, volcanoes, and ocean storms-massive movements of earth, air, fire, and water-generate infrasound. In the past, very-low-frequency sound was not thought to play much of a role in animals' lives. However, we know now that sound at the lowest frequencies of elephant rumbles (14Hz to 35Hz) has remarkable properties. It is lit- tle affected by passage through forests and grasslands, and male and female elephants use it to find one another for reproduction. It seems that elephants communicate with one another by using calls that are too low-pitched for human beings to hear, and because of the properties of the infrasound range, these communications can take place over very long distances. Intense infrasonic calls have also been recorded from finback whales. Figure 1.6 shows the electromagnetic spectrum and where some of the va