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Although development of the first radio wave communication system is attributed to Guglielmo Marconi, his was just the practical application of 80 years of scientific advancement in the field including the predictions of Michael Faraday, the theoretical work of James Clerk Maxwell, and the experimental demonstrations of Heinrich Rudolf Hertz. [1]
Ring-and-spring microphones, such as this Western Electric microphone, were common during the electrical age of sound recording c. 1925–45.. The second wave of sound recording history was ushered in by the introduction of Western Electric's integrated system of electrical microphones, electronic signal amplifiers and electromechanical recorders, which was adopted by major US record labels in ...
Frances Densmore and Blackfoot chief Mountain Chief working on a recording project of the Bureau of American Ethnology (1916).. Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects.
Key Takeaways: The human auditory pathway involves an intricate chain of events, beginning with pressure waves in the air that cause air particles to vibrate.
Human communication was initiated with the origin of speech approximately 100,000 BCE. [1] Symbols were developed about 30,000 years ago. The imperfection of speech allowed easier dissemination of ideas and eventually resulted in the creation of new forms of communication, improving both the range at which people could communicate and the longevity of the information.
Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation. In an 1864 presentation, published in 1865, James Clerk Maxwell proposed theories of electromagnetism and mathematical proofs demonstrating that light, radio and x-rays were all types of electromagnetic waves propagating through free space.
Before the discovery of electromagnetic waves and the development of radio communication, there were many wireless telegraph systems proposed and tested. [4] In April 1872 William Henry Ward received U.S. patent 126,356 for a wireless telegraphy system where he theorized that convection currents in the atmosphere could carry signals like a telegraph wire. [5]
Having heard the signal, it is easy to identify the sonar equipment used (usually with its frequency) and its position (with the sound wave's energy). Active sonar is similar to radar in that, while it allows detection of targets at a certain range, it also enables the emitter to be detected at a far greater range, which is undesirable.