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Throat Microphone
A throat microphone, also called a laryngophone, is a type of contact microphone that absorbs vibrations directly from the wearer's throat by way of single or dual sensors worn against the neck. The sensors, called transducers, can pick up speech even in extremely noisy or windy environments, such as on a motorcycle or in a nightclub. Other types of microphones do not function well under these conditions because of high levels of background noise. Advanced laryngophones are able to pick up whispers, and therefore perform well in environments where communicating with others at a distance in silence is required, such as during covert military or law enforcement operations. Throat microphones are also very useful when helmets or respiratory protection is required. Many full-face SCBA, CABA, SAR Respirator, Elastomeric Respirator, N95 Respirator PAPR, or re-breather masks do not have a provision for a microphone inside the mask. The throat microphone can be used safely, as it is pos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen Mask KM-34
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula . Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Army Air Forces
The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II (1941–1945). It was created on 20 June 1941 as successor to the previous United States Army Air Corps and is the direct predecessor of the United States Air Force, today one of the six United States Armed Forces, armed forces of the United States. The AAF was a component of the United States Army, which on 2 March 1942 was divided functionally by executive order into three autonomous forces: the Army Ground Forces, the United States Army Services of Supply (which in 1943 became the Army Service Forces), and the Army Air Forces. Each of these forces had a commanding general who reported directly to the Chief of Staff of the United States Army, Army Chief of Staff. The AAF administered all parts of military aviation formerly distributed am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leather Flying Helmet
During the first years of aviation, pilots started wearing leather flying helmets as a form of protection from the cold and the noise of aircraft engines. Leather was becoming a popular choice for protective gear with the rise of motor sport and aviation at the start of the 1900s. It has many advantages that made it the ideal material for flying helmets. It is warm, durable, impermeable to liquids therefore waterproof, flexible and can be cut to curve around the head. It is wind-proof and has the great advantage of not accumulating dust. It was also found that leather helmets offered a level of protection against fire. British Engineers led by Charles Edmond Prince added Throat microphones & earphones into these helmets during World War I for hands free communications in the noisy and windy environment of aircraft cockpits.The National ArchivesFighting talk: First World War telecommunications/ref>IEEE SpectrumIn World War I, British Biplanes Had Wireless Phones in the Cockpit/ref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silent Speech Interface
Silent speech interface is a device that allows speech communication without using the sound made when people vocalize their speech sounds. As such it is a type of electronic lip reading. It works by the computer identifying the phonemes that an individual pronounces from nonauditory sources of information about their speech movements. These are then used to recreate the speech using speech synthesis. Information sources Silent speech interface systems have been created using ultrasound and optical camera input of tongue and lip movements. Electromagnetic devices are another technique for tracking tongue and lip movements. The detection of speech movements by electromyography of speech articulator muscles and the larynx is another technique. Another source of information is the vocal tract resonance signals that get transmitted through bone conduction called non-audible murmurs. They have also been created as a brain–computer interface using brain activity in the motor corte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subvocal Recognition
Subvocal recognition (SVR) is the process of taking subvocalization and converting the detected results to a digital output, aural or text-based. Concept A set of electrodes are attached to the skin of the throat and, without opening the mouth or uttering a sound, the words are recognized by a computer. Subvocal speech recognition deals with electromyograms that are different for each speaker. Therefore, consistency can be thrown off just by the positioning of an electrode. To improve accuracy, researchers in this field are relying on statistical models that get better at pattern-matching the more times a subject "speaks" through the electrodes, but even then there are lapses. At Carnegie Mellon University, researchers found that the same "speaker" with accuracy rates of 94% one day can see that rate drop to 48% a day later; between two different speakers it drops even more. Relevant applications for this technology where audible speech is impossible: for astronauts, underwate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise-canceling Microphone
A noise-canceling microphone is a microphone that is designed to filter ambient noise. Technical details The development is a special case of the differential microphone topology most commonly used to achieve directionality. All such microphones have at least two ports through which sound enters; a front port normally oriented toward the desired sound and another port that's more distant. The microphone's diaphragm is placed between the two ports; sound arriving from an ambient sound field reaches both ports more or less equally. Sound that's much closer to the front port than to the rear will make more of a pressure gradient between the front and back of the diaphragm, causing it to move more. The microphone's proximity effect is adjusted so that flat frequency response is achieved for sound sources very close to the front of the mic – typically 1 to 3 cm. Sounds arriving from other angles are subject to steep midrange and bass rolloff. Commercially and militarily usefu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise-cancelling Headphones
Noise-cancelling headphones reduce unwanted ambient sounds using active noise control. This is distinct from passive headphones which, if they reduce ambient sounds at all, use techniques such as soundproofing. Noise cancellation makes it possible to listen to audio content without raising the volume excessively. It can also help a passenger sleep in a noisy vehicle such as an airliner. In the aviation environment, noise-cancelling headphones increase the signal-to-noise ratio significantly more than passive noise attenuating headphones or no headphones, making hearing important information such as safety announcements easier. Noise-cancelling headphones can improve listening enough to completely offset the effect of a distracting concurrent activity. Theory To cancel the lower-frequency portions of the noise, noise-cancelling headphones use active noise control or ANC. A microphone captures the targeted ambient sounds, and a small amplifier generates sound waves that are exactly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
COVID-19
Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was COVID-19 pandemic in Hubei, identified in Wuhan, China, in December 2019. The disease quickly spread worldwide, resulting in the COVID-19 pandemic. The symptoms of COVID‑19 are variable but often include fever, cough, headache, fatigue, breathing difficulties, Anosmia, loss of smell, and Ageusia, loss of taste. Symptoms may begin one to fourteen days incubation period, after exposure to the virus. At least a third of people who are infected Asymptomatic, do not develop noticeable symptoms. Of those who develop symptoms noticeable enough to be classified as patients, most (81%) develop mild to moderate symptoms (up to mild pneumonia), while 14% develop severe symptoms (dyspnea, Hypoxia (medical), hypoxia, or more than 50% lung involvement on imaging), and 5% develop critical symptoms (respiratory failure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airsoft
Airsoft is a team game in which participants eliminate opposing players by tag (game), tagging them out of play with airsoft pellets, spherical plastic projectiles shot with mock air gun, air weapons(usually powered by an electronic motor) called airsoft guns. Although similar to paintball in concept and gameplay, airsoft pellets do not leave visible markings on their target and hits are not always apparent. Though the pellets leave bruises or welts on exposed skin (and so protective gear is recommended), the game relies heavily on an honor system in which players who have been Terminal ballistics, hit are expected to call themselves out. The airsoft guns used are mostly magazine (firearms), magazine-fed, with some having manual/battery (electricity), battery-powered spring (device), spring-piston pump powerplant, power plants similar to Nerf Blasters, or pneumatically powered by replaceable compressed gas (e.g. propane ("green gas"), 1,1,1,2-tetrafluoroethane or ) gas cylinder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrestrial Trunked Radio
Terrestrial Trunked Radio (TETRA; formerly known as Trans-European Trunked Radio), a European standard for a trunked radio system, is a professional mobile radio and two-way transceiver specification. TETRA was specifically designed for use by government agencies, emergency services, (police forces, fire departments, ambulance) for public safety networks, rail transport staff for train radios, transport services and the military. TETRA is the European version of trunked radio, similar to Project 25. TETRA is a European Telecommunications Standards Institute (ETSI) standard, first version published 1995; it is mentioned by the European Radiocommunications Committee (ERC). Description TETRA uses time-division multiple access (TDMA) with four user channels on one radio carrier and 25 kHz spacing between carriers. Both point-to-point and point-to-multipoint transfer can be used. Digital data transmission is also included in the standard though at a low data rate. TETRA Mob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Law Enforcement
Law enforcement is the activity of some members of government who act in an organized manner to enforce the law by discovering, deterring, rehabilitating, or punishing people who violate the rules and norms governing that society. The term encompasses police, courts, and corrections. These three components may operate independently of each other or collectively, through the use of record sharing and mutual cooperation. The concept of law enforcement dates back to ancient times, and forms of law enforcement and police have existed in various forms across many human societies. Modern state legal codes use the term peace officer, or law enforcement officer, to include every person vested by the legislating state with police power or authority; traditionally, anyone sworn or badged, who can arrest any person for a violation of criminal law, is included under the umbrella term of law enforcement. Although law enforcement may be most concerned with the prevention and punishment o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
