One reason that the U.S. Navy decided in 2013 to make a break between the previously closely linked Interior Communications Electrician rating (IC) and Electrician’s Mate (EM) is that the rapid advances in communications technology required more demanding levels of education in networking and computer technology. An Interior Communications Electrician Third Class (E4), for example, maintains a highly complex Integrated Voice Communication System Network (IVCN) based on Avaya’s Definity G3 or Multivantage Communications Suite, which in turn requires the networking know-how to set up and run Avaya’s S8700 Media Servers employed in single- and multi-node IVCN systems.

But one tool intimately familiar to Sailors in the IC rating requires almost no technical expertise at all. In fact, it doesn’t even require electricity.

Research into developing a sound-powered telephone began in the mid-1930s as the Navy sought to replace the “speaking tubes”—only slightly more technologically advanced a system of Dixie Cups and strings—then in use aboard all its ships. The concept is simple: The sound waves of the speaker’s voice cause vibrations in a diaphragm which are then transferred to an armature, effectively converting the sound waves into a small electrical current. The current goes out to receivers, where the process is reversed and the current is changed back to sound waves.

Using ordinary landlines, the Marines that invaded Guadalcanal were able to communicate at distances of up to ten miles with sound-powered phones, and even the early shipboard versions worked so well that up to twenty people could receive a telephone transmission from one person. Though such a setup may seem rather primitive in our high-tech world of digital communications, the sound-powered telephone has an advantage that is indisputable: It can be used when there is absolutely no electricity available aboard a ship, a scenario that is increasingly possible as research into electro-magnetic pulse (EMP) weapons continues.


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