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Acoustic Mirror
An acoustic mirror is a passive device used to reflect and focus (concentrate) sound waves. Parabolic reflector, Parabolic acoustic mirrors are widely used in parabolic microphones to pick up sound from great distances, employed in surveillance and reporting of outdoor sporting events. Pairs of large parabolic acoustic mirrors which function as "Whispering gallery, whisper galleries" are displayed in science museums to demonstrate sound focusing. Interwar period, Between the World Wars, before the invention of radar, parabolic sound mirrors were used experimentally as early-warning devices by military air defence forces to detect incoming enemy aircraft by listening for the sound of their engines. During World War II on the coast of southern England, a network of large concrete acoustic mirrors was in the process of being built when the project was cancelled owing to the development of the Chain Home radar system. Some of these mirrors are still standing today. Acoustic air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redcar
Redcar is a seaside town on the Yorkshire Coast in the Redcar and Cleveland unitary authority. It is in the ceremonial county of North Yorkshire, England, and is located east of Middlesbrough. The Teesside built-up area's Redcar subdivision had a population of 37,073 at the 2011 Census. The town is made up of Coatham, Dormanstown, Kirkleatham, Newcomen, West Dyke, Wheatlands and Zetland. It gained a town charter in 1922, from then until 1968 it was governed by the municipal borough of Redcar. Since the abolition of County Borough of Teesside, which existed from 1968 until 1974, the town has been unparished. History Origins Redcar occupies a low-lying site by the sea; the second element of its name is from Old Norse ''kjarr'', meaning 'marsh', and the first may be either Old English (Anglo-Saxon) ''rēad'' meaning 'red' or OE ''hrēod'' 'reed'. The town originated as a fishing hamlet in the 14th century, trading with the larger adjacent hamlet of Coatham. U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whispering Dish, Jodrell Bank
Whispering is an unvoiced mode of phonation in which the vocal cords are abducted so that they do not vibrate; air passes between the arytenoid cartilages to create audible turbulence during speech. Supralaryngeal articulation remains the same as in normal speech. In normal speech, the vocal cords alternate between states of voice and voicelessness. In whispering, only the voicing segments change, so that the vocal cords alternate between whisper and voicelessness (though the acoustic difference between the two states is minimal). Because of this, implementing speech recognition for whispered speech is more difficult, as the characteristic spectral range needed to detect syllables and words is not given through the total absence of tone. More advanced techniques such as neural networks may be used, however, as is done by Amazon Alexa. There is no symbol in the IPA for whispered phonation, since it is not used phonemically in any language. However, a sub-dot under phonemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Sansome Tucker
Major William Sansome Tucker (1877 Kidderminster, Worcestershire – 1965 Guelph, Ontario, Canada) was an English pioneer in acoustical research and inventor of the acoustic mirror. Early life Tucker was born in Kidderminster, the son of William Tucker, an artist painter, and his wife Anna. Tucker married in Chorlton-on-Medlock, Lancashire, in 1906. Career Tucker lectured on physics in London. Following the outbreak of World War I, Tucker joined the British Army as a private soldier. He was posted to the Experimental Sound Ranging Station at Kemmel Hill in Belgium which was under the command of Lawrence Bragg. As part of the London Electrical Engineers, Territorial Force, Tucker was granted a commission, being promoted from lance corporal to temporary second lieutenant, General List in April 1916. At Kemmel Hill, Tucker undertook research into 'sound ranging': the process of using microphones and mathematics to determine the position of enemy artillery. Bragg had been wracked ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arecibo Observatory
The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science Foundation (NSF). The observatory's main instrument was the Arecibo Telescope, a spherical reflector dish built into a natural sinkhole, with a cable-mount steerable receiver and several radar transmitters for emitting signals mounted above the dish. Completed in 1963, it was the world's largest single-aperture telescope for 53 years, surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. On August 10 and November 6, 2020, two of the receiver's support cables broke and the NSF announced that it would decommission the telescope. The telescope collapsed on December 1, 2020. In 2022, the NSF announced the telescope will not be rebuilt, with an educational facility to be established on the site. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
English Channel
The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busiest Sea lane, shipping area in the world. It is about long and varies in width from at its widest to at its narrowest in the Strait of Dover."English Channel". ''The Columbia Encyclopedia'', 2004. It is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some . The Channel aided the United Kingdom in becoming a naval superpower, serving as a natural defence against invasions, such as in the Napoleonic Wars and in the World War II, Second World War. The northern, English coast of the Channel is more populous than the southern, French coast. The major languages spoken in this region are English language, English and French language, French. Names Roman historiography, Roman sources as (or , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focus (geometry)
In geometry, focuses or foci (; : focus) are special points with reference to which any of a variety of curves is constructed. For example, one or two foci can be used in defining conic sections, the four types of which are the circle, ellipse, parabola, and hyperbola. In addition, two foci are used to define the Cassini oval and the Cartesian oval, and more than two foci are used in defining an n-ellipse, ''n''-ellipse. Conic sections Defining conics in terms of two foci An ellipse can be defined as the locus (mathematics), locus of points for which the sum of the distances to two given foci is constant. A circle is the special case of an ellipse in which the two foci coincide with each other. Thus, a circle can be more simply defined as the locus of points each of which is a fixed distance from a single given focus. A circle can also be defined as the Circles of Apollonius, circle of Apollonius, in terms of two different foci, as the locus of points having a fixed ratio of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microphone
A microphone, colloquially called a mic (), or mike, is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, and radio and television broadcasting. They are also used in computers and other electronic devices, such as mobile phones, for recording sounds, speech recognition, Voice over IP, VoIP, and other purposes, such as Ultrasonic transducer, ultrasonic sensors or knock sensors. Several types of microphone are used today, which employ different methods to convert the air pressure variations of a sound wave to an electrical signal. The most common are the dynamic microphone, which uses a coil of wire suspended in a magnetic field; the condenser microphone, which uses the vibrating Diaphragm (acoustics), diaphragm as a capacitor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concrete
Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactured material in the world. When aggregate is mixed with dry Portland cement and water, the mixture forms a fluid slurry that can be poured and molded into shape. The cement reacts with the water through a process called hydration, which hardens it after several hours to form a solid matrix that binds the materials together into a durable stone-like material with various uses. This time allows concrete to not only be cast in forms, but also to have a variety of tooled processes performed. The hydration process is exothermic, which means that ambient temperature plays a significant role in how long it takes concrete to set. Often, additives (such as pozzolans or superplasticizers) are included in the mixture to improve the physical prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Il-Widna
''Il-Widna'' is a large acoustic mirror located in Magħtab, Malta. The colloquial name of the acoustic mirror refers to ear in Maltese. The mirror is long, approximately the same design as the sound Mirror in RAF Denge. The mirror was used during the Axis bombardment of Malta during the Second World war to detect incoming Luftwaffe (1941-1942) and Regia Aeronautica (1940-1941) bombers seeking to airstrike Malta. Il-Widna faces towards the island of Sicily, in Italy at a bearing of around 20 degrees. The mirror is also the only acoustic not built in the UK. Il-Widna was built between the autumn of 1934 and the summer of 1935. The required electrical equipment was installed in the first weeks of September 1935. The total cost of the development of the mirror on Malta was put at £4500. Tests making use of a flying boat found that the range of the mirror was around . It was estimated that the mirror would provide a six minute warning of an enemy aircraft An aircraft ( aircra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malta
Malta, officially the Republic of Malta, is an island country in Southern Europe located in the Mediterranean Sea, between Sicily and North Africa. It consists of an archipelago south of Italy, east of Tunisia, and north of Libya. The two official languages are Maltese language, Maltese and English language, English. The country's capital is Valletta, which is the smallest capital city in the EU by both area and population. It was also the first World Heritage Site, World Heritage City in Europe to become a European Capital of Culture in 2018. With a population of about 542,000 over an area of , Malta is the world's List of countries and dependencies by area, tenth-smallest country by area and the List of countries and dependencies by population density, ninth-most densely populated. Various sources consider the country to consist of a single urban region, for which it is often described as a city-state. Malta has been inhabited since at least 6500 BC, during the Mesolith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
