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Echo
In audio signal processing and acoustics, an echo is a reflection of sound that arrives at the listener with a delay after the direct sound. The delay is directly proportional to the distance of the reflecting surface from the source and the listener. Typical examples are the echo produced by the bottom of a well, a building, or the walls of enclosed and empty rooms. Etymology The word ''echo'' derives from the Greek ἠχώ (''ēchō''), itself from ἦχος (''ēchos''), 'sound'. Echo in Greek mythology was a mountain nymph whose ability to speak was cursed, leaving her able only to repeat the last words spoken to her. Nature Some animals, such as cetaceans (dolphins and whales) and bats, use echo for location sensing and navigation, a process known as echolocation. Echoes are also the basis of sonar technology. Acoustic phenomenon Walls or other hard surfaces, such as mountains and privacy fences, reflect acoustic waves. The reason for reflection may be explained as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Echolocation
Echolocation, also called bio sonar, is a biological active sonar used by several animal groups, both in the air and underwater. Echolocating animals emit calls and listen to the Echo (phenomenon) , echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects. Echolocation is used for animal navigation , navigation, foraging, and predation, hunting prey. Echolocation calls can be Frequency modulation, frequency modulated (FM, varying in pitch during the call) or constant frequency (CF). FM offers precise range discrimination to localize the prey, at the cost of reduced operational range. CF allows both the prey's velocity and its movements to be detected by means of the Doppler effect. FM may be best for close, cluttered environments, while CF may be better in open environments or for hunting while perched. Echolocating animals include mammals, especially odontocetes (toothed whales) and some bat species, and, using s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echo Cardiography
Echocardiography, also known as cardiac ultrasound, is the use of ultrasound to examine the heart. It is a type of medical imaging, using standard ultrasound or Doppler ultrasound. The visual image formed using this technique is called an echocardiogram, a cardiac echo, or simply an echo. Echocardiography is routinely used in the diagnosis, management, and follow-up of patients with any suspected or known heart diseases. It is one of the most widely used diagnostic imaging modalities in cardiology. It can provide a wealth of helpful information, including the size and shape of the heart (internal chamber size quantification), pumping capacity, location and extent of any tissue damage, and assessment of valves. An echocardiogram can also give physicians other estimates of heart function, such as a calculation of the cardiac output, ejection fraction, and diastolic function (how well the heart relaxes). Echocardiography is an important tool in assessing wall motion abnormality in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Echo
image:Light Echo Corrected.png, 309x309px, Reflected light following path B arrives shortly after the direct flash following path A but before light following path C. B and C have the same apparent distance from the star as seen from Earth. A light echo is a physical phenomenon caused by light reflection (physics), reflected off surfaces distant from the source, and arriving at the observer with a delay relative to this distance. The phenomenon is analogous to an echo (phenomenon), echo of sound, but due to the much faster speed of light, it mostly manifests itself only over astronomical distances. For example, a light echo is produced when a sudden flash from a nova is reflected off a cosmic dust, cosmic dust cloud, and arrives at the viewer after a longer duration than it otherwise would have taken with a direct path. Because of their geometry, geometries, light echoes can produce the illusion of superluminal motion. Explanation Light echoes are produced when the initial flas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delay (audio Effect)
Delay is an audio signal processing technique that records an input signal to a storage medium and then plays it back after a period of time. When the delayed playback is electronic mixer, mixed with the live audio, it creates an echo-like effect, whereby the original audio is heard followed by the delayed audio. The delayed signal may be played back multiple times, or fed back into the recording, to create the sound of a repeating, decaying echo. Delay effects range from a subtle echo effect to a pronounced blending of previous sounds with new sounds. Delay effects can be created using tape loops, an approach developed in the 1940s and 1950s and used by artists including Elvis Presley and Buddy Holly. Analog effects units were introduced in the 1970s; digital effects pedals in 1984; and audio plug-in software in the 2000s. History The first delay effects were achieved using tape loops improvised on reel-to-reel audio tape recording systems. By shortening or lengthening the loo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrasonography
Medical ultrasound includes diagnostic techniques (mainly imaging) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound. The usage of ultrasound to produce visual images for medicine is called medical ultrasonography or simply sonography, or echography. The practice of examining pregnant women using ultrasound is called obstetric ultrasonography, and was an early development of clinical ultrasonography. The machine used is called an ultrasound machine, a sonograph or an echograph. The visual image formed using this technique is called an ultrasonogram, a sonogram or an echogram. Ultrasound is composed of sound waves with frequencies greater than 20,000 Hz, which is the approximate upper threshold of human h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances ( ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: ''passive'' sonar means listening for the sound made by vessels; ''active'' sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and sodar (an upward-looking in-air sonar) is used for atmospheric investigations. The term ''sonar'' is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low ( infrasonic) to e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echo Depth Sounding
Echo sounding or depth sounding is the use of sonar for ranging, normally to determine the depth of water (bathymetry). It involves transmitting acoustic waves into water and recording the time interval between emission and return of a pulse; the resulting time of flight, along with knowledge of the speed of sound in water, allows determining the distance between sonar and target. This information is then typically used for navigation purposes or in order to obtain depths for charting purposes. Echo sounding can also be used for ranging to other targets, such as fish schools. Hydroacoustic assessments have traditionally employed mobile surveys from boats to evaluate fish biomass and spatial distributions. Conversely, fixed-location techniques use stationary transducers to monitor passing fish. The word '' sounding'' is used for all types of depth measurements, including those that don't use sound, and is unrelated in origin to the word ''sound'' in the sense of noise or tone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effects Unit
An effects unit, effects processor, or effects pedal is an electronic device that alters the sound of a musical instrument or other audio source through audio signal processing. Common effects include distortion (music), distortion/overdrive, often used with electric guitar in electric blues and rock music; dynamics (music), dynamic effects such as volume pedals and Dynamic range compression, compressors, which affect loudness; linear filter, filters such as wah-wah pedals and graphic equalizers, which modify frequency ranges; modulation effects, such as Chorus (audio effect), chorus, flangers and phaser (effect), phasers; Pitch (music), pitch effects such as pitch shifter (audio processor), pitch shifters; and time effects, such as Reverb effect, reverb and Delay (audio effect), delay, which create echoing sounds and emulate the sound of different spaces. Most modern effects use solid-state electronics or digital signal processors. Some effects, particularly older ones such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrasonic Waves
Ultrasound is sound with frequencies greater than 20 kilohertz. This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound. Ultrasonic devices operate with frequencies from 20 kHz up to several gigahertz. Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasound imaging or sonography is often used in medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning, mixing, and accelerating chemical processes. Animals such as bats and porpoises use ultrasound for locating prey and obstacles. History Acoustics, the science of sound, starts as far back as Pythagoras in the 6th century BC, who wrote on the mathematical properties of stringed instruments. Echolocation in bats was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetacea
Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel themselves through the water with powerful up-and-down movements of their tail, which ends in a paddle-like fluke, using their flipper-shaped forelimbs to steer. While the majority of cetaceans live in marine environments, a small number reside solely in brackish water, brackish or fresh water. Having a cosmopolitan distribution, they can be found in some rivers and all of Earth's oceans, and many species migrate throughout vast ranges with the changing of the seasons. Cetaceans are famous for cetacean intelligence, their high intelligence, complex social behaviour, and the enormous size of some of the group's members. For example, the blue whale reaches a maximum confirmed length of and a weight of 173 tonne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echoplex
The Echoplex is a tape delay effects unit, first made in 1959. Designed by engineer Mike Battle, the Echoplex set a standard for the effect in the 1960s; according to Michael Dregni, it is still regarded as "the standard by which everything else is measured." The Echoplex was widely used in the 1960s and 1970s, mainly by guitarists but also by other performers, and original Echoplexes are highly sought after. Background Tape echoes work by recording sound on a magnetic tape, which is then played back; the tape speed and distance between the recording and playback heads determine the delay time, while a feedback variable (where the delayed sound is fed back into the input) allows for multiple echoes. The predecessor of the Echoplex was a tape echo designed by Ray Butts in the 1950s, who built it into a guitar amplifier called the EchoSonic. Butts built fewer than seventy EchoSonics for guitarists including Chet Atkins, Scotty Moore, and Carl Perkins. Mike Battle later copied ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recording Studio
A recording studio is a specialized facility for Sound recording and reproduction, recording and Audio mixing, mixing of instrumental or vocal musical performances, spoken words, and other sounds. They range in size from a small in-home project studio large enough to record a single singer-guitarist, to a large building with space for a full orchestra of 100 or more musicians. Ideally, both the Studio recording, recording and monitoring (listening and mixing) spaces are specially designed by an acoustician or audio engineer to achieve optimum acoustic properties (acoustic isolation or diffusion or absorption of reflected sound reverberation that could otherwise interfere with the sound heard by the listener). Recording studios may be used to record singers, instrumental musicians (e.g., electric guitar, piano, saxophone, or ensembles such as orchestras), voice-over artists for advertisements or Dubbing, dialogue replacement in film, television, or animation, Foley (filmmaking) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
