Why Forgotten Acoustic Mirror Networks Stand | ABANDONED

acoustic mirrors also known as sound mirrors or listening ears are large concrete structures that were built in the early 20th century as warning devices for detecting approaching enemy aircraft this was preliminary technology before the development of the radar resulting in vast complexes of these massive now obsolete structures dotting the globe so join us as we discover what remains of the Forgotten acoustic mirror Network I'm your host Ryan silcash and you're watching its history [Music] believe it or not the concept of using reflected sound for various purposes has a pre-history that can be traced all the way back to ancient times well the specific term acoustic mirror may not have been used then there are instances of early civilizations utilizing the principles of sound reflection and concentration both ancient Greek and Roman theaters were designed with curved seating areas and semi-circular horseshoe-shaped amphitheaters these architectural designs were intended to enhance the Acoustics allowing the sound to be projected and reflected towards the audience amplifying the voices of the actors and musicians the Greeks and Romans also constructed Echo Chambers in buildings or outdoor spaces these Chambers had curved or concave surfaces that would reflect sound waves in a way that created Echoes or Amplified specific frequencies however this type of Technology wasn't limited to Europe as as the best example of the echo wall was in the temple of the heaven complex in Beijing China the Americans were also up to speed on this the Incas of ancient Peru were known to incorporate acoustic principles into their architecture structures such as the Temple of the Sun at Machu Picchu were built with specifically shaped stones that could produce resonant sound effects when struck these structures were possibly used for ceremonial or communication purposes finally we have the whispering galleries an architectural feature found in some religious buildings and structures these spaces take advantage of sound reflection to create unique acoustic effects one famous example of This Whispering Gallery is in Saint Paul's Cathedral in London where the curved interior of the Dome allows Whispers spoken near the walls to be heard on the opposite side due to the sound waves following the curved surface another example of this could be found here at the red Monastery in Slovakia where monks would gather annually to hear updates about the outside world using the simple principles of sound reflection their whisper chamber allowed them to receive and give the news with dignity in other words they utilized the same principles that would become known as the acoustic mirror centuries later the principle of sound reflection is Central to the functioning of acoustic mirrors when sound waves encounter a surface such as the curved shape of an acoustic mirror they undergo reflection in the case of the acoustic mirrors the concave or a parabolic shape was carefully designed to redirect sound waves towards a specific focal point as the sound waves reach the mirror's surface they would bounce off the curved surface causing them to converge and concentrate at the focal point in turn this focused concentration of sound waves at the focal point allowed for the amplification of faint sounds such as the noise produced by distant aircraft engines so imagine the possibilities in a time without radar by positioning an observer with listening devices at the focal point the mirrored surface could effectively capture and redirect sound enabling the detection of incoming aircraft in other words the concept of sound reflection is based on the principle that when sound waves strike a surface they change direction for this reason the shape and curvature of the acoustic mirror were carefully calculated to optimize the reflection of the sound waves towards the desired location by harnessing the principle of sound reflection acoustic mirrors played a crucial role in early sound detection systems providing a means to amplify and concentrate sound waves for improved detection of potential threats making it the perfect solution for militaries worldwide military usage of acoustic mirror technology began in the early 20th century primarily During the interwar period between World War one and World War II the exact timeline of its adoption and implementation varied among countries but it generally emerged in the 1910s and gained prominence in the 1920s and 30s the UK was at the Forefront of developing and utilizing acoustic mirror years for military purposes following the end of World War One the British military recognized the need for improved early Warning Systems against potential aerial threats as a result they started experimenting with sound detection Technologies eventually leading to the construction of acoustic mirrors along their coastlines other countries such as France Germany and Australia also explored the use of these mirrors during this period though to a lesser extent each Nation adopted the technology to its specific defense needs and Coastal locations considering the advantages the rise of these systems was immediate with networks sprawling across the globe But ultimately they served no purpose in fact to the best of our research there are no documented cases of acoustic mirrors directly saving countries from attack for one the effectiveness of acoustic mirrors was limited while they could amplify faint aircraft engine noises and provide some advanced warning they had significant drawbacks the detection range was relatively short and the effectiveness of the technology relied on favorable weather conditions and the specific trajectory of approaching aircraft furthermore the rise of radar technology during the 1930s quickly surpassed the capabilities of acoustic mirrors in terms of accuracy range and reliability so naturally radar became the primary means of aircraft detection rendering acoustic mirrors Obsolete and leading to their gradual abandonment so the fact of the matter is that acoustic mirrors played a role in early warning detection systems but their impact in directly saving countries from Attack was limited simply put the transition to more advanced radar technology provided a more meaningful defense against aerial threats the earliest form of radar which laid the foundation for sub Point developments was called radio detection and ranging also known as rdf this was an early system that used radio waves to detect the presence and location of objects including aircraft and ships rdf was developed in the late 19th and early 20th centuries and underwent significant advancements during World War II one notable early application for rdf was the quote chain home a system developed by the British in the late 1930s chain home utilized a network of radio transmitters and receivers to detect and track incoming aircraft and it played a critical role in the air defense of Britain during the Battle of Britain in 1940 another early form of radar was the oboe system developed by the British in the early 1940s oboe was a Precision bombing Aid that used ground-based radar to guide aircraft in accurately dropping their bombs on specific targets these early radar systems paved the way for further advancements in radar technology including improved range accuracy and Target identification capabilities the development and deployment of radar systems during World War II marked a significant milestone in the evolution of radar technology leading to its widespread use in various military and civilian applications categorically killing the acoustic mirror most of our stories revolve around topics within the U.S so I was surprised to discover that aside from the listening stone at Saint vraine Greenway in Longmont Colorado which is a very cool Modern Art installation created by local artist Christopher weed nothing remains of the few American mirrors that may have been built you see the US didn't invest as heavily in acoustic mirrors as some other countries did during the early 20th century as the states had a different approach to coastal defense basically rather than relying extensively on acoustic mirrors the US focused on other Technologies and defense systems including early prototypes for radar you see the US was ahead of the curve they knew that sound mirrors would become useless there was also the geography and topography of the United States which has vast coastal areas such expansive territory made constructing and maintaining a large-scale network of acoustic mirrors Logistics challenging and potentially less effective as compared to other available defense measures however across the pond in the UK was an entirely different situation the United Kingdom constructed many acoustic mirrors along its coastal areas during the 1920s and 1930s these mirrors were strategically positioned to provide early warning and detection of incoming aircraft threats the British network of acoustic mirrors was particularly extensive and Relics have indeed been left behind for example fan Bay deep shelter in Dover includes a well-preserved acoustic mirror underground tunnels and shelters that were part of the World War II defenses The National Trust manages the area and it is open to the public the cement installations almost look like alien technology etched into the rocks from thousands of years ago when in reality there are just over a century old located near folkstone is Abbott its Cliff home to a partially collapsed and eroded acoustic mirror visible from the coastal path well it is not accessible up close visitors can still observe it from a distance on one hand if you have some context these look like the standard military Tech of the era but on the other hand to an unsuspecting tourist their monolith-like shape contrasts the coast in a way that might feel a bit creepy in East Yorkshire is the killed sea Sound Mirror which is enormous and qualifies as one of the largest surviving acoustic mirrors in the UK it's situated on the Cliff's Edge and can be viewed from a public footpath although it's not accessible for closer inspection the Dungeness sound mirrors near Dungeness Kent are a well-known cluster of acoustic mirrors they include the more prominent listening ears and the smaller listening lips these mirrors are largely derelict and in disrepair but but they remain visible as a testament to early sound detection technology the height sound mirrors were two experimental acoustic mirrors built on an area known as the roughs just west of Hythe and Kent the smaller mirror was constructed first then the larger one was added nearby over the past 20 years the elements and vandals have taken their toll leaving little behind Beyond raw foundations and soon they will be lost forever from ancient Human Society to the Modern Day acoustic mirrors still hold architectural significance because in many ways they're analogous to similar modern technology which digital systems have enhanced although these days Acoustic sound mirrors for practical applications are limited certain Concepts and technologies have drawn inspiration from the principles of sound reflection and focusing employed in acoustic mirrors throughout time and I'm sure you didn't even notice their presence for instance in Acoustics parabolic reflectors concentrate sound waves or direct them towards specific areas of Interest such as outdoor public address systems or directional speakers this is almost always a consideration for designers laying the blueprint for open air venues it is also interesting to consider that you can create a center of attention with Acoustics alone reflective antennas and wireless communication systems frequently rely on the same principle another example will well not directly related to acoustic mirrors are systems that utilize the principles of sound reflection and time-of-flight measurements to detect and locate objects underwater some surviving mirrors have been preserved as cultural heritage sites or landmarks leading me to wonder will America's best abandoned satellite Network enjoy the same fate we could find out by making a video on that topic and if you'd like to see that happen let me know by clicking subscribe otherwise until next time I'm Ryan sokash signing off

Channel: IT'S HISTORY

Views: 99,270

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Id: yalWtcRmUsI

Length: 13min 35sec (815 seconds)

Published: Thu Jul 20 2023