NationMaster - Encyclopedia: Sound power

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

Sound power or acoustic power P_ac is a measure of sonic energy E per time t unit.
It is measured in watts, or sound intensity I times area A: // Sound pressure Sound pressure is the pressure deviation from the local ambient pressure caused by a sound wave. ... It has been suggested that this article or section be merged into Sound pressure. ... Particle velocity is the velocity v of a particle (real or imagined) in a medium as it transmits a wave. ... 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 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 schematic representation of hearing. ... A pocket watch. ... 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. ...

$P_{mathrm{acoustic}} = I cdot A$

The measure of a ratio of two sound powers is

$L_mathrm{w}=10, log_{10}left(frac{P_1}{P_0}right) mathrm{dB}$

where

P₁, P₀ are the sound powers.

The sound power level PWL, L_W, or L_Pac of a source is expressed in decibels (dB) and is equal to 10 times the logarithm to the base 10 of the ratio of the sound power of the source to a reference sound power. It is thus a logarithmic measure. 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 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 common logarithm is the logarithm with base 10. ... A logarithmic scale is a scale of measurement that uses the logarithm of a physical quantity instead of the quantity itself. ...

The reference sound power in air is normally taken to be 10⁻¹² watt = 0 dB SWL.

Sound power is neither room dependent nor distance dependent, like it is with sound pressure or sound intensity. Sound power belongs strictly to the sound source. There is no decrease of power with distance.

Table: Sound power and und sound power level of some sound sources

Situation and sound source	sound power P_ac	sound power legel L_w
refrigerator	10^-7 W	50 dB
usual talking, typewriter	10^-5 W	70 dB
loud speech, vivid children	0.001 W	90 dB
helicopter	0.01 W	100 dB
chain saw	0.1 W	110 dB
excavator, trumpet	0.3 W	115 dB
jack hammer	1 W	120 dB
machine gun	10 W	130 dB
heavy diesel and loud- speaker rock concert	100 W	140 dB
siren	1.000 W	150 dB
turbo-jet-engine	10,000 W	160 dB
rocket engine	1,000,000 W	180 dB

Usable music sound (trumpet) and noise sound (excavator) have both the same sound power of 0.3 watts, but will be judged psychoacoustically to be different levels. It has been suggested that this article or section be merged into refrigeration. ... Mechanical desktop typewriters, such as this Underwood Five, were long time standards of government agencies, newsrooms, and sales offices. ... The Bell 206 of Canadian Helicopters Robinson Helicopter Company (USA) R44, a four seat development of the R22 A helicopter is an aircraft which is lifted and propelled by one or more horizontal rotors. ... Alternative meaning: Chainsaw (computer program) A chainsaw (also spelled chain saw) is a portable mechanical, motorized saw. ... A tracked excavator by Daewoo. ... Trumpeter redirects to here. ... The word jackhammer is also used in the name of the type of combat shotgun called the Pancor Jackhammer. ... A machine gun is a fully-automatic firearm that is capable of firing bullets in rapid succession. ... Diesel or Diesel fuel is a specific fractional distillate of fuel oil (mostly petroleum) that is used as fuel in a diesel engine invented by German engineer Rudolf Diesel. ... The term, rock concert, refers to a musical performance in the style of any one of many genres inspired by rock and roll music. ... A Greek amphora depicting Odysseus encounter with the sirens. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... A Redstone rocket, part of the Mercury program The traditional definition of a rocket is a vehicle, missile or aircraft which obtains thrust by the reaction to the ejection of fast moving exhaust gas from within a rocket engine. ... Psychoacoustics is the study of subjective human perception of sounds. ...

Sound power with plain sound waves

Between sound power and other important acoustic values there is the following relationship:

$P_{ak} = &# 0;2 cdot omega^2 cdot Z cdot A = v^2 cdot Z cdot A = frac{a^2 cdot Z cdot A}{omega^2} = frac{p^2 cdot A}{Z} = E cdot c cdot A = I cdot A$

where:

Symbol	Units	Meaning
p	Pa	sound pressure
f	Hz	frequency
ξ	m	particle displacement
c	m/s	speed of sound
v	m/s	particle velocity
ω = 2πf	rad/s	angular frequency
ρ	kg/m³	density of air
Z = c · ρ	N·s/m³	acoustic impedance
a	m/s²	particle acceleration
I	W/m²	sound intensity
E	W·s/m³	sound energy density
P_ac	W	sound power or acoustic power
A	m²	area

Look up Pa, PA, and pa in Wiktionary, the free dictionary. ... // Sound pressure Sound pressure is the pressure deviation from the local ambient pressure caused by a sound wave. ... 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 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. ... The metre, or meter (symbol: m) is the SI base unit of length. ... Look up second in Wiktionary, the free dictionary. ... The speed of sound c (from Latin celeritas, velocity) varies depending on the medium through which the sound waves pass. ... 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. ... Particle velocity is the velocity v of a particle (real or imagined) in a medium as it transmits a wave. ... The radian (symbol: rad, or a superscript c ( half circle)) is the SI unit of plane angle. ... 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 international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... The metre, or meter (symbol: m) is the SI base unit of length. ... The density of air, Ï (Greek: rho) (air density), is the mass per unit volume of Earths atmosphere, and is a useful value in aeronautics. ... 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 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. ... 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 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. ...

External links

Ohm's law of the acoustics - calculations
Connection of acoustic sizes for even progressive acoustic waves

Categories: Sound | Measurement | Power

Results from FactBites:

Noise and Hearing Conservation Technical Manual Chapter: Noise and Health Effects (App I:A-3) (827 words)
	Sound Power (W) is the amount of energy per unit time that radiates from a source in the form of an acoustic wave.
	This distribution of sound power over the area of the propagating wave is designated as intensity and is measured in units of watts per square meter.
	Sound power is analogous to the power rating of a light bulb.

Sound - Wikipedia, the free encyclopedia (752 words)
	Sound is characterized by the properties of sound waves which are frequency, wavelength, period, amplitude and velocity or speed.
	Sound propagates as waves of alternating pressure, causing local regions of compression and rarefaction.
	Sound velocity c or velocity of sound should not be confused with sound particle velocity v, which is the velocity of the individual particles.

More results at FactBites »

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Sound power with plain sound waves

External links

Table: Sound power and und sound power level of some sound sources