The absolute threshold of hearing (ATH) is the minimum sound level of a pure tone that an average human ear with normal hearing can hear with no other sound present.
Acoustics is the branch of physics that deals with the study of all mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound.
Africa is the world's second largest and second most-populous continent (behind Asia in both categories).
Alternating current (AC) is an electric current which periodically reverses direction, in contrast to direct current (DC) which flows only in one direction.
Angular displacement of a body is the angle in radians (degrees, revolutions) through which a point revolves around a centre or line has been rotated in a specified sense about a specified axis.
In physics, angular frequency ω (also referred to by the terms angular speed, radial frequency, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate.
In mathematics, an argument of a function is a specific input in the function, also known as an independent variable.
Asia is Earth's largest and most populous continent, located primarily in the Eastern and Northern Hemispheres.
An audio frequency (abbreviation: AF) or audible frequency is characterized as a periodic vibration whose frequency is audible to the average human.
An audio signal is a representation of sound, typically as an electrical voltage for analog signals and a binary number for digital signals.
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands.
In colloquial language, an average is a middle or typical number of a list of numbers.
Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies.
In physics and electrical engineering, a cutoff frequency, corner frequency, or break frequency is a boundary in a system's frequency response at which energy flowing through the system begins to be reduced (attenuated or reflected) rather than passing through.
The cycle per second was a once-common English name for the unit of frequency now known as the hertz.
In digital signal processing, decimation is the process of reducing the sampling rate of a signal.
In dimensional analysis, a dimensionless quantity is a quantity to which no physical dimension is assigned.
A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other.
In mathematics and in particular mathematical dynamics, discrete time and continuous time are two alternative frameworks within which to model variables that evolve over time.
In optics, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency.
In physical sciences and electrical engineering, dispersion relations describe the effect of dispersion in a medium on the properties of a wave traveling within that medium.
A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people).
Division is one of the four basic operations of arithmetic, the others being addition, subtraction, and multiplication.
An electric field is a vector field surrounding an electric charge that exerts force on other charges, attracting or repelling them.
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current.
In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.
Electronic filters are circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both.
Engineering is the creative application of science, mathematical methods, and empirical evidence to the innovation, design, construction, operation and maintenance of structures, machines, materials, devices, systems, processes, and organizations.
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere.
A frequency band is an interval in the frequency domain, delimited by a lower frequency and an upper frequency.
A frequency changer or frequency converter is an electronic or electromechanical device that converts alternating current (AC) of one frequency to alternating current of another frequency.
A frequency counter is an electronic instrument, or component of one, that is used for measuring frequency.
In statistics, a frequency distribution is a list, table or graph that displays the frequency of various outcomes in a sample.
In electronics, control systems engineering, and statistics, the frequency domain refers to the analysis of mathematical functions or signals with respect to frequency, rather than time.
In broadcast engineering, a frequency extender is an electronic device that allows high-fidelity analogue audio to be sent over regular POTS telephone lines, without the loss of higher audio frequencies (treble).
A frequency grid is a table of all the central frequencies (and corresponding wavelengths) of channels allowed in a communications system.
In telecommunications and signal processing, frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave.
A gamma ray or gamma radiation (symbol γ or \gamma), is penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei.
Hearing loss, also known as hearing impairment, is a partial or total inability to hear.
Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it.
Heinrich Rudolf Hertz (22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves theorized by James Clerk Maxwell's electromagnetic theory of light.
The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second.
Heterodyning is a signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden that creates new frequencies by combining or mixing two frequencies.
Infrared radiation (IR) is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye (although IR at wavelengths up to 1050 nm from specially pulsed lasers can be seen by humans under certain conditions). It is sometimes called infrared light.
In sociology, interaction frequency is the total number of social interactions per unit time.
The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.
Lambda, Λ, λ (uppercase Λ, lowercase λ; λάμ(β)δα lám(b)da) is the 11th letter of the Greek alphabet.
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.
In electronics, a logic gate is an idealized or physical device implementing a Boolean function; that is, it performs a logical operation on one or more binary inputs and produces a single binary output.
A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials.
Mains electricity (as it is known in the UK; US terms include grid power, wall power, and domestic power) is the general-purpose alternating-current (AC) electric power supply.
Mains hum, electric hum, or power line hum is a sound associated with alternating current at the frequency of the mains electricity.
A measuring instrument is a device for measuring a physical quantity.
The metre (British spelling and BIPM spelling) or meter (American spelling) (from the French unit mètre, from the Greek noun μέτρον, "measure") is the base unit of length in some metric systems, including the International System of Units (SI).
Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter; with frequencies between and.
In the music theory of Western culture, a minor third is a musical interval that encompasses three half steps, or semitones.
Monochrome describes paintings, drawings, design, or photographs in one color or values of one color.
In mathematics, a multiplicative inverse or reciprocal for a number x, denoted by 1/x or x−1, is a number which when multiplied by x yields the multiplicative identity, 1.
In music, a note is the pitch and duration of a sound, and also its representation in musical notation (♪, ♩).
Natural frequency is the frequency at which a system tends to oscillate in the absence of any driving or damping force.
The concept of negative and positive frequency can be as simple as a wheel rotating one way or the other way: a signed value of frequency can indicate both the rate and direction of rotation.
Neil Harbisson (born 27 July 1984) is a Catalan-raised, Northern Irish-born cyborg artist and transpecies activist based in New York City.
North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere; it is also considered by some to be a northern subcontinent of the Americas.
Nu (uppercase Ν lowercase ν; νι ni) or ny is the 13th letter of the Greek alphabet.
Observational error (or measurement error) is the difference between a measured value of a quantity and its true value.
Omega (capital: Ω, lowercase: ω; Greek ὦ, later ὦ μέγα, Modern Greek ωμέγα) is the 24th and last letter of the Greek alphabet.
Optical heterodyne detection is a method of extracting information encoded as modulation of the phase and/or frequency (wavelength) of electromagnetic radiation in the wavelength band of visible or infrared light.
An optical medium is material through which electromagnetic waves propagate.
Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it.
Oscillation is the repetitive variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states.
Periodicity or periodic may refer to.
Phase is the position of a point in time (an instant) on a waveform cycle.
The phase velocity of a wave is the rate at which the phase of the wave propagates in space.
Physics (from knowledge of nature, from φύσις phýsis "nature") is the natural science that studies matterAt the start of The Feynman Lectures on Physics, Richard Feynman offers the atomic hypothesis as the single most prolific scientific concept: "If, in some cataclysm, all scientific knowledge were to be destroyed one sentence what statement would contain the most information in the fewest words? I believe it is that all things are made up of atoms – little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another..." and its motion and behavior through space and time and that studies the related entities of energy and force."Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves."Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. (...) You will come to see physics as a towering achievement of the human intellect in its quest to understand our world and ourselves."Physics is an experimental science. Physicists observe the phenomena of nature and try to find patterns that relate these phenomena.""Physics is the study of your world and the world and universe around you." Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over the last two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the scientific revolution in the 17th century, these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy. Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.
Pink noise or noise is a signal or process with a frequency spectrum such that the power spectral density (energy or power per frequency interval) is inversely proportional to the frequency of the signal.
Pitch is a perceptual property of sounds that allows their ordering on a frequency-related scale, or more commonly, pitch is the quality that makes it possible to judge sounds as "higher" and "lower" in the sense associated with musical melodies.
The Planck constant (denoted, also called Planck's constant) is a physical constant that is the quantum of action, central in quantum mechanics.
A preselector is a name for an electronic device that connects between a radio antenna and a radio receiver.
A quartz clock is a clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time.
A radar system uses a radio frequency electromagnetic signal reflected from a target to determine information about that target.
The radian (SI symbol rad) is the SI unit for measuring angles, and is the standard unit of angular measure used in many areas of mathematics.
Radio is the technology of using radio waves to carry information, such as sound, by systematically modulating properties of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light.
In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies.
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min) is the number of turns in one minute.
A rotation is a circular movement of an object around a center (or point) of rotation.
Russia (rɐˈsʲijə), officially the Russian Federation (p), is a country in Eurasia. At, Russia is the largest country in the world by area, covering more than one-eighth of the Earth's inhabited land area, and the ninth most populous, with over 144 million people as of December 2017, excluding Crimea. About 77% of the population live in the western, European part of the country. Russia's capital Moscow is one of the largest cities in the world; other major cities include Saint Petersburg, Novosibirsk, Yekaterinburg and Nizhny Novgorod. Extending across the entirety of Northern Asia and much of Eastern Europe, Russia spans eleven time zones and incorporates a wide range of environments and landforms. From northwest to southeast, Russia shares land borders with Norway, Finland, Estonia, Latvia, Lithuania and Poland (both with Kaliningrad Oblast), Belarus, Ukraine, Georgia, Azerbaijan, Kazakhstan, China, Mongolia and North Korea. It shares maritime borders with Japan by the Sea of Okhotsk and the U.S. state of Alaska across the Bering Strait. The East Slavs emerged as a recognizable group in Europe between the 3rd and 8th centuries AD. Founded and ruled by a Varangian warrior elite and their descendants, the medieval state of Rus arose in the 9th century. In 988 it adopted Orthodox Christianity from the Byzantine Empire, beginning the synthesis of Byzantine and Slavic cultures that defined Russian culture for the next millennium. Rus' ultimately disintegrated into a number of smaller states; most of the Rus' lands were overrun by the Mongol invasion and became tributaries of the nomadic Golden Horde in the 13th century. The Grand Duchy of Moscow gradually reunified the surrounding Russian principalities, achieved independence from the Golden Horde. By the 18th century, the nation had greatly expanded through conquest, annexation, and exploration to become the Russian Empire, which was the third largest empire in history, stretching from Poland on the west to Alaska on the east. Following the Russian Revolution, the Russian Soviet Federative Socialist Republic became the largest and leading constituent of the Union of Soviet Socialist Republics, the world's first constitutionally socialist state. The Soviet Union played a decisive role in the Allied victory in World War II, and emerged as a recognized superpower and rival to the United States during the Cold War. The Soviet era saw some of the most significant technological achievements of the 20th century, including the world's first human-made satellite and the launching of the first humans in space. By the end of 1990, the Soviet Union had the world's second largest economy, largest standing military in the world and the largest stockpile of weapons of mass destruction. Following the dissolution of the Soviet Union in 1991, twelve independent republics emerged from the USSR: Russia, Ukraine, Belarus, Kazakhstan, Uzbekistan, Armenia, Azerbaijan, Georgia, Kyrgyzstan, Moldova, Tajikistan, Turkmenistan and the Baltic states regained independence: Estonia, Latvia, Lithuania; the Russian SFSR reconstituted itself as the Russian Federation and is recognized as the continuing legal personality and a successor of the Soviet Union. It is governed as a federal semi-presidential republic. The Russian economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it one of the leading producers of oil and natural gas globally. The country is one of the five recognized nuclear weapons states and possesses the largest stockpile of weapons of mass destruction. Russia is a great power as well as a regional power and has been characterised as a potential superpower. It is a permanent member of the United Nations Security Council and an active global partner of ASEAN, as well as a member of the G20, the Shanghai Cooperation Organisation (SCO), the Council of Europe, the Asia-Pacific Economic Cooperation (APEC), the Organization for Security and Co-operation in Europe (OSCE), and the World Trade Organization (WTO), as well as being the leading member of the Commonwealth of Independent States (CIS), the Collective Security Treaty Organization (CSTO) and one of the five members of the Eurasian Economic Union (EEU), along with Armenia, Belarus, Kazakhstan and Kyrgyzstan.
In signal processing, sampling is the reduction of a continuous-time signal to a discrete-time signal.
The second is the SI base unit of time, commonly understood and historically defined as 1/86,400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each.
SI derived units are units of measurement derived from the seven base units specified by the International System of Units (SI).
A signal as referred to in communication systems, signal processing, and electrical engineering is a function that "conveys information about the behavior or attributes of some phenomenon".
In telecommunication, signaling has the following meanings.
In mathematics, the sine is a trigonometric function of an angle.
A sine wave or sinusoid is a mathematical curve that describes a smooth periodic oscillation.
In physics, sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.
Sound recording and reproduction is an electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects.
South America is a continent in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere.
In mathematics, physics, and engineering, spatial frequency is a characteristic of any structure that is periodic across position in space.
In logic, especially as applied in mathematics, concept is a special case or specialization of concept precisely if every instance of is also an instance of but not vice versa, or equivalently, if is a generalization of.
In biology, a species is the basic unit of classification and a taxonomic rank, as well as a unit of biodiversity, but it has proven difficult to find a satisfactory definition.
In telecommunications, spectral component is any of the waves that range outside the interval of frequencies assigned to a signal.
The power spectrum S_(f) of a time series x(t) describes the distribution of power into frequency components composing that signal.
The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.
The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium.
In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g., an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth.
A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light.
A stroboscope also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving, or stationary.
In music, timbre (also known as tone color or tone quality from psychoacoustics) is the perceived sound quality of a musical note, sound or tone.
A transducer is a device that converts energy from one form to another.
;In radio engineering: a transverter is a radio frequency device that consists of an upconverter and a downconverter in one unit.
A turn is a unit of plane angle measurement equal to 2pi radians, 360 degrees or 400 gradians.
Ultraviolet (UV) is electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays.
A unit of time or time unit is any particular time interval, used as a standard way of measuring or expressing duration.
In digital signal processing, upsampling can refer to the entire process of increasing the sampling rate of a signal, or it can refer to just one step of the process, the other step being interpolation.
Vacuum is space devoid of matter.
When used without any further description, vector usually refers either to.
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point.
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye.
In physics, a wave is a disturbance that transfers energy through matter or space, with little or no associated mass transport.
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
In the physical sciences, the wavenumber (also wave number or repetency) is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance.
In fluid dynamics, wind waves, or wind-generated waves, are surface waves that occur on the free surface of bodies of water (like oceans, seas, lakes, rivers, canals, puddles or ponds).
X-rays make up X-radiation, a form of electromagnetic radiation.
Frekvens, Frequencies, Frequency (wave motion), Frequency dependence, Frequency measurement, Ordinary frequency, Oscillation frequency, Oscillation rate, Period (frequency), Periodic time, Rate of oscillation, Rate of repetition, Repetition frequency, Repetition rate, Temporal frequency, Wave frequency, Wave period.