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Active Noise Reduction
Active noise control (ANC), also known as noise cancellation (NC), or active noise reduction (ANR), is a method for reducing unwanted sound by the addition of a second sound specifically designed to cancel the first. The concept was first developed in the late 1930s; later developmental work that began in the 1950s eventually resulted in commercial airline Headset (audio), headsets with the technology becoming available in the late 1980s. The technology is also used in road vehicles, mobile telephones, earbuds, and headphones. Explanation Sound is a P-wave, pressure wave, which consists of alternating periods of Compression (physical), compression and rarefaction. A noise-cancellation speaker emits a sound wave with the same amplitude but with an inverted phase (also known as antiphase) relative to the original sound. The waves combine to form a new wave, in a process called Interference (wave propagation), interference, and effectively cancel each other out – an effect whi ... [...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] |
IEEE
The Institute of Electrical and Electronics Engineers (IEEE) is an American 501(c)(3) organization, 501(c)(3) public charity professional organization for electrical engineering, electronics engineering, and other related disciplines. The IEEE has a corporate office in New York City and an operations center in Piscataway, New Jersey. The IEEE was formed in 1963 as an amalgamation of the American Institute of Electrical Engineers and the Institute of Radio Engineers. History The IEEE traces its founding to 1884 and the American Institute of Electrical Engineers. In 1912, the rival Institute of Radio Engineers was formed. Although the AIEE was initially larger, the IRE attracted more students and was larger by the mid-1950s. The AIEE and IRE merged in 1963. The IEEE is headquartered in New York City, but most business is done at the IEEE Operations Center in Piscataway, New Jersey, opened in 1975. The Australian Section of the IEEE existed between 1972 and 1985, after which it s ... [...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 u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coherence (physics)
Coherence expresses the potential for two waves to Wave interference, interfere. Two Monochromatic radiation, monochromatic beams from a single source always interfere. Wave sources are not strictly monochromatic: they may be ''partly coherent''. When interfering, two waves add together to create a wave of greater amplitude than either one (constructive Wave interference, interference) or subtract from each other to create a wave of minima which may be zero (destructive interference), depending on their relative phase (waves), phase. Constructive or destructive interference are limit cases, and two waves always interfere, even if the result of the addition is complicated or not remarkable. Two waves with constant relative phase will be coherent. The amount of coherence can readily be measured by the interference visibility, which looks at the size of the interference fringes relative to the input waves (as the phase offset is varied); a precise mathematical definition of the de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adaptive Noise Cancelling
Adaptive noise cancelling is a signal processing technique that is highly effective in suppressing additive interference or noise corrupting a received target signal at the main or primary sensor in certain common situations where the interference is known and is accessible but unavoidable and where the target signal and the interference are unrelated (i.e., uncorrelated).Kaunitz, J. (August 1972)"Adaptive Filtering of Broadband Signals as Applied to Noise Cancelling,"Stanford Electronics Laboratories Rep. SU-SEL-3-038, Stanford University, Stanford, California, (Ph.D. dissertation) OCLC 15201972Widrow, B., Glover, J., R. McCool, J. M., Kaunitz, J., Williams, C. S., Hearn, R. H., Zeidler, J. R., Dong E. JR, and Goodlin, R. C. (December 1975) Adaptive Noise Cancelling: Principles and Applications" Proc. IEEE, Vol. 63, DOI: 10.1109/PROC.1975.10036Widrow, B. and Stearns S. D. (1985) "Adaptive Signal Processing," Pearson Education, Inc. , 0130040290 OCLC 11159524 Examples of such s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Sound Design
Active sound design is an acoustic technology concept used in automotive vehicles to alter or enhance the sound inside and outside of the vehicle. Active sound design (ASD) often uses active noise control and acoustic enhancement techniques to achieve a synthesized vehicle sound. The typical implementations of ASD vary, from amplifying or reducing an existing sound to creating an entirely new sound. Each vehicle manufacturer may use different software or hardware techniques in ASD, as there is no one unified model. ASD exists under multiple names, like Acura’Active Sound Control Kia’Active Sound System Volkswagen’s Soundaktor, and QNX’Acoustic Management System The first instance of in-vehicle active noise canceling (ANC) was developed by Lotus and featured in the 1992 Nissan Bluebird. In 2009, Lotus partnered with Harman International for an improved ANC system that eliminated noise from the road, tires, and vehicle chassis. With recent demand for economical and clea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel–cadmium Battery
The nickel–cadmium battery (Ni–Cd battery or NiCad battery) is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes. The abbreviation ''Ni–Cd'' is derived from the chemical symbols of nickel (Ni) and cadmium (Cd): the abbreviation ''NiCad'' is a registered trademark of Saft Groupe S.A., SAFT Corporation, although this brand name is genericized trademark, commonly used to describe all Ni–Cd batteries. Battery (electricity)#Wet cell, Wet-cell nickel–cadmium batteries were invented in 1899. A Ni–Cd battery has a terminal voltage during discharge of around 1.2 volts which decreases little until nearly the end of discharge. The maximum electromotive force offered by a Ni–Cd cell is 1.3V. Ni–Cd batteries are made in a wide range of sizes and capacities, from portable sealed types interchangeable with carbon–zinc dry cells, to large ventilated cells used for standby power and motive power. Compared with other types of rechargeab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lawrence J
Lawrence may refer to: Education Colleges and universities * Lawrence Technological University, a university in Southfield, Michigan, United States * Lawrence University, a liberal arts university in Appleton, Wisconsin, United States Preparatory & high schools * Lawrence Academy at Groton, a preparatory school in Groton, Massachusetts, United States * Lawrence College, Ghora Gali, a high school in Pakistan * Lawrence School, Lovedale, a high school in India * The Lawrence School, Sanawar, a high school in India Research laboratories * Lawrence Berkeley National Laboratory, United States * Lawrence Livermore National Laboratory, United States People * Lawrence (given name), including a list of people with the name * Lawrence (surname), including a list of people with the name * Lawrence (band), an American soul-pop group * Lawrence (judge royal) (died after 1180), Hungarian nobleman, Judge royal 1164–1172 * Lawrence (musician), Lawrence Hayward (born 1961), British m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Vibration Control
Active vibration control is the active application of force in an equal and opposite fashion to the forces imposed by external vibration. With this application, a precision industrial process can be maintained on a platform essentially vibration-free. Many precision industrial processes cannot take place if the machinery is being affected by vibration. For example, the production of semiconductor Wafer (electronics), wafers requires that the machines used for the photolithography steps be used in an essentially vibration-free environment or the sub-micrometre features will be blurred. Active vibration control is now also commercially available for reducing vibration in helicopters, offering better comfort with less weight than traditional passive technologies. In the past, passive techniques were used. These include traditional vibration Damping ratio, dampers, shock absorbers, and base isolation. The typical active vibration control system uses several components: * A massive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karaoke Machine
is a type of interactive entertainment system usually offered in nightclubs and bars, where people sing along to pre-recorded accompaniment using a microphone. Its musical content is an instrumental rendition of a well-known popular song. In recent times, lyrics are typically displayed on a video screen, along with a moving symbol, changing colour, or music video images, to guide the singer. In Chinese-speaking countries and regions such as mainland China, Hong Kong, Taiwan and Singapore, a karaoke box is called a KTV. The global karaoke market has been estimated to be worth nearly $10 billion. Karaoke's global popularity has been fueled by technological advancements, making it a staple of social gatherings and entertainment venues all over the world. The precursors of karaoke machines using cassette tapes made their first appearances in Japan and the Philippines in the 1970s. Commercial versions manufactured by Japanese companies using LaserDisc became available worldwi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
