NationMaster - Encyclopedia: Particle velocity

Sound measurements
Sound pressure p
Sound pressure level (SPL)
Particle velocity v
Particle velocity level (SVL)
(Sound velocity level)
Particle displacement ξ
Sound intensity I
Sound intensity level (SIL)
Sound power P_ac
Sound power level (SWL)
Sound energy density E
Sound energy flux q
Acoustic impedance Z
Speed of sound c

Particle velocity is the velocity v of a particle (real or imagined) in a medium as it transmits a wave. In many cases this is a longitudinal wave of pressure as with sound, but it can also be a transverse wave as with the vibration of a taut string. Sound p (or acoustic pressure) is the measurement in pascals of the root mean square (RMS) pressure deviation (from atmospheric pressure) caused by a sound wave passing through a fixed point. ... It has been suggested that this article or section be merged into Sound pressure. ... The particle velocity level or the sound velocity level tells the ratio of a sound incidence in comparison to a reference level of 0 dB. It shows the ratio of the particle velocity v1 and the particle velocity v0. ... Particle displacement or particle amplitude (represented in mathematics by the lower-case Greek letter Î¾) is a measurement of distance (in metres) of the movement of a particle in a medium as it transmits a wave. ... The sound intensity, I, (acoustic intensity) is defined as the sound power Pac per unit area A. The usual context is the measurement of sound intensity in the air at a listeners location. ... Sound intensity level or acoustic intensity level is a logarithmic measure of the sound intensity in comparison to the reference level of 0 dB (decibels). ... Sound power or acoustic power Pac is a measure of sonic energy E per time t unit. ... Sound power level or acoustic power level is a logarithmic measure of the sound power in comparison to the reference level of 0 dB (decibels). ... The sound energy density or sound density (symbol E or w) is an adequate measure to describe the sound field at a given point as a sound energy value. ... The sound energy flux is the average rate of flow of sound energy for one period through any specified area. ... The acoustic impedance Z (or sound impedance) is the ratio of sound pressure p to particle velocity v in a medium or acoustic component. ... The speed of sound c (from Latin celeritas, velocity) varies depending on the medium through which the sound waves pass. ... A transmission medium is any material substance, such as fiber-optic cable, twisted-wire pair, coaxial cable, dielectric-slab waveguide, water, or air, that can be used for the propagation of signals, usually in the form of modulated radio, light, or acoustic waves, from one point to another. ... A wave is a disturbance that propagates through space, often transferring energy. ... Longitudinal waves, also referred to as compressional waves or pressure waves, are waves that have vibrations along or parallel to their direction of travel. ... Pressure (symbol: p) is the force per unit area acting on a surface in a direction perpendicular to that surface. ... A light wave is an example of a transverse wave. ...

When applied to a sound wave through a medium of air, particle velocity would be the physical speed of an air molecule as it moves back and forth in the direction the sound wave is travelling as it passes.

Particle velocity should not be confused with the speed of the wave as it passes through the medium, i.e. in the case of a sound wave, particle velocity is not the same as the speed of sound. In applications involving sound, Particle velocity is usually measured using a logarithmic decibel scale called particle velocity level. A wave is a disturbance that propagates through space, often transferring energy. ... The speed of sound c (from Latin celeritas, velocity) varies depending on the medium through which the sound waves pass. ... The decibel (dB) is a measure of the ratio between two quantities, and is used in a wide variety of measurements in acoustics, physics and electronics. ... The particle velocity level or the sound velocity level tells the ratio of a sound incidence in comparison to a reference level of 0 dB. It shows the ratio of the particle velocity v1 and the particle velocity v0. ...

Equations in terms of other measurements

Symbol	Units	Meaning
v	m/s	particle velocity
ξ	m, meters	particle displacement
σ = 2πf	radians/s	angular frequency
f	Hz, hertz	frequency
p	Pa, pascals	sound pressure
Z	N·s/m³	acoustic impedance
I	W/m²	sound intensity
E	W·s/m³	sound energy density
P_ac	W, watts	sound power or acoustic power
A	m²	area
a	m/s²	particle acceleration

Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... The metre, or meter (symbol: m) is the SI base unit of length. ... Particle displacement or particle amplitude (represented in mathematics by the lower-case Greek letter Î¾) is a measurement of distance (in metres) of the movement of a particle in a medium as it transmits a wave. ... In mathematics and physics, the radian is a unit of angle measure. ... Look up second in Wiktionary, the free dictionary. ... Angular frequency is a measure of how fast an object is rotating In physics (specifically mechanics and electrical engineering), angular frequency ω (also called angular speed) is a scalar measure of rotation rate. ... The hertz (symbol: Hz) is the SI unit of frequency. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... The pascal (symbol Pa) is the SI unit of pressure. ... Sound p (or acoustic pressure) is the measurement in pascals of the root mean square (RMS) pressure deviation (from atmospheric pressure) caused by a sound wave passing through a fixed point. ... The newton (symbol: N) is the SI unit of force. ... Look up second in Wiktionary, the free dictionary. ... The metre, or meter (symbol: m) is the SI base unit of length. ... The acoustic impedance Z (or sound impedance) is the ratio of sound pressure p to particle velocity v in a medium or acoustic component. ... The watt (symbol: W) is the SI derived unit of power. ... The sound intensity, I, (acoustic intensity) is defined as the sound power Pac per unit area A. The usual context is the measurement of sound intensity in the air at a listeners location. ... The watt (symbol: W) is the SI derived unit of power. ... Look up second in Wiktionary, the free dictionary. ... The metre, or meter (symbol: m) is the SI base unit of length. ... The sound energy density or sound density (symbol E or w) is an adequate measure to describe the sound field at a given point as a sound energy value. ... The watt (symbol: W) is the SI derived unit of power. ... Sound power or acoustic power Pac is a measure of sonic energy E per time t unit. ... Sound power or acoustic power is a measure of sonic energy E per time t unit. ... The metre, or meter (symbol: m) is the SI base unit of length. ... Area is a physical quantity expressing the size of a part of a surface. ... The metre, or meter (symbol: m) is the SI base unit of length. ... Look up second in Wiktionary, the free dictionary. ... In a compressible sound transmission medium - mainly air - air particles get an accelerated motion: the particle acceleration or sound acceleration with the symbol a in metre/secondÂ². In acoustics or physics, acceleration (symbol: a) is defined as the rate of change (or time derivative) of velocity. ...

External links

Ohm's law of the acoustics - calculations
Connection of acoustic sizes for even progressive acoustic waves
The particle velocity can be directly measured with a Microflown

Categories: Sound | Fluid dynamics | Acoustics

Results from FactBites:

ParticleAPI: PContextActions_t Class Reference (3893 words)
	Particles are tested to see whether they will pass from being outside the specified domain to being inside it within look_ahead time units from now if the next Move() action were to occur now.
	Particles are tested to see whether they will pass from being outside the specified domain to being inside it if the next Move() action were to occur now.
	Since particles are tested to see whether they would pass through the domain if Move() were called now, it is best to have Bounce() be the last action that modifies a particle's velocity before calling Move().

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Equations in terms of other measurements

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