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Topic: Sound pressure level

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Sound energy density

Sound intensity level

Particle velocity

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Decibel

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	Sound pressure - Wikipedia, the free encyclopedia
		Sound pressure is the pressure deviation from the local ambient pressure caused by a sound wave.
		The SI unit for sound pressure is the pascal (symbol: Pa).
		sound pressure and p is the root-mean-square sound pressure being measured.
	en.wikipedia.org /wiki/Sound_pressure_level (917 words)

	NPC Library: Noise Control Terms Made Somewhat Easier
		Measured in phons it is numerically equal to the median sound pressure level (dB) of a free progressive 1000 Hz wave presented to listeners facing the source, which in a number of trials is judged by the listeners to be equally loud.
		The sound field very near to a source, where the sound pressure does not obey the inverse-square law and the particle velocity is not in phase with the sound pressure.
		A measure of the sound absorption of a surface; it is the equivalent of one square foot of a perfectly absorptive surface.
	www.nonoise.org /library/diction/soundict.htm (3820 words)

	OSHA Content Document
		However, the sound pressure level at some distance (r) from the source is dependant on that distance and the sound-absorbing characteristics of the environment.
		The magnitude of the sound pressure from a given sound source, however, depends on the distance from the source and the characteristics of the environmental surroundings.
		The sound pressure level at a distance of 20 feet from the source would be calculated as follows (since the source is located on the ground, the equation for hemispherical radiation from a point source is used):
	www.osha.gov /dts/osta/otm/noise/health_effects/soundpropagation.html (814 words)

	Sound Power and Sound Pressure
		What is heard is a sound pressure level that is determined, for any particular location, by many factors, including size of the room, nature of its walls, ceilings, furnishings, etc. The pressure level at the point of hearing is also related to the distance from the sound source.
		Sound pressure is a pressure disturbance in the atmosphere whose intensity is influenced not only by the strength of the source, but also by the surroundings and the distance from the source to the receiver.
		These figures refer to the sound pressure levels that should be experienced by an observer at a certain distance from the motor in a given environment, which is generally assumed to be a free field.
	www.usmotors.com /products/ProFacts/sound_power_and_sound_pressure.htm (1361 words)

	Essential Accessories: The Radio Shack Sound Pressure Level Meter
		The perceived loudness of the sound we hear is proportional to the pressure of the sound wave.
		Having the ability to measure the pressure level of a sound wave in a listening room is extremely useful when attempting to optimize the room's loudspeaker and listener positions.
		The Radio Shack sound pressure level meter is a small hand-held device for measuring the pressure level of a sound wave in an acoustic environment such as your listening room.
	www.audiophilia.com /hardware/spl.htm (1682 words)

	SOUND LEVELS
		The fact that the ratio of the sound pressure of the loudest sound (before the sensation of sound is changed into pain) to the sound pressure of the lowest one is about 1,000,000 has led to the adoption of a compressed scale called a logarithmic scale.
		The sound pressure level has the advantage of being an objective yet a handy measure of sound intensity, but it has the drawback that it is far from being an accurate measure of what is actually perceived.
		For instance, an 80-phon sound is not twice as loud as a 40-phon one.
	www.eie.fceia.unr.edu.ar /~acustica/comite/soundlev.htm (1320 words)

	Institute of Noise Control Engineering USA
		Noise whose level abruptly drops to the level of the background noise several times during the period of observation, the time during which the level remains at a constant value different from that of the ambient being of the order of 1 s or more.
		Airborne sound received at the ear of an observer being a composite of all sounds in the vicinity of the observer.
		Sound field in which the time average of the mean-square sound pressure is everywhere the same and the flow of acoustic energy in all directions is equally probable.
	www.inceusa.org /pubs.glossary.asp (3410 words)

	Sound level SPL in dB - pressure level L sound pressure p sound intensity I - dB conversion of sound units calculating ... (Site not responding. Last check: 2007-10-19)
		Sound level SPL in dB - pressure level L sound pressure p sound intensity I - dB conversion of sound units calculating spl sound level calculation air - sengpielaudio
		The volume (loudness) is determined by the sound pressure p and expressed as sound pressure level L
		peaking of the intensity of sound pressure is nonsense.
	www.sengpielaudio.com /calculator-soundlevel.htm (379 words)

	Sound pressure and loudness (Site not responding. Last check: 2007-10-19)
		Pressure amplitude on the other hand is easy to measure [microphones do this by converting pressure waves into mechanical motion, into an electrical signal that can be measured].
		The sound pressure levels in decibels is related to the pressure, p by:
		Sound intensity level measures the level of sound at a given distance from a given source.
	carini.physics.indiana.edu /P105S98/Pressure-and-loudness.html (894 words)

	Theremin Vox - Sound Pressure Level
		is the reference sound pressure and p1 is the sound pressure being measured.
		When making measurements in air, SPL is almost always expressed in decibels compared to a reference sound pressure of 20 µPa (micropascals), which is usually considered the threshold of human hearing.
		The most common means is measuring the sound pressure level from the speaker with the measuring device placed directly in front of and one meter away from the source.
	www.thereminvox.com /article/articleprint/169/-1/37 (403 words)

	Sound Power and Intensity
		For a sound wave, the amount of energy transported is proportional to the square of the amplitude of the wave.
		Both sound pressure level and sound intensity level are purported to measure the same thing: the loudness of a sound that we hear.
		The next step to show the equality of sound pressure level and sound intensity level is to realize that the intensity in a sound wave is proportional to the square of the amplitude of the sound wave.
	hep.physics.indiana.edu /~rickv/Sound_intensity.html (912 words)

	Muzzle Blast Sound Intensity, Firearm Sound Pressure Level
		Sound pressure level (SPL) is the objective measure of sound intensity, loudness is the perceptual correlate.
		Unfortunately, sound level meters don't accurately measure the SPL of rifles because the duration of the sound (excluding echoes from surrounding hills or trees) is very short.
		Sound level meters are but one type of instrument used to analyze sound: Other measuring devices are used to measure characteristics of sound other than intensity.
	www.elcaudio.com /decibel.htm (5796 words)

	Sound - Wikipedia, the free encyclopedia
		Sound is characterized by the properties of sound waves, which are frequency, wavelength, period, amplitude and velocity or speed.
		In general, the speed of sound is proportional to the square root of the ratio of the stiffness of the medium and its density.
		In a soundwave, the complementary variable to sound pressure is the acoustic particle velocity.
	en.wikipedia.org /wiki/Sound_level (993 words)

	Measurement of Sound Transmission Loss- Developer Zone - National Instruments
		The sound transmission loss is 10 times the logarithm of the reciprocal of the ratio of the energy transmitted through the specimen to the energy incident on the specimen.
		The measurement is based on the assumption that the sound fields in the source chamber are diffuse, and that the receiving chamber is a nominally free field environment.
		The constant 6-dB term arises from the fact that the angle of incidence of the energy in the source chamber is random in orientation, and that the sound pressure level in the source chamber is proportional to the total energy incident on the specimen.
	zone.ni.com /devzone/cda/tut/p/id/1488 (1166 words)

	ProSoundWeb \| LSI: The Sound Level Arms Race
		The loudness (level) of a sound is stated in decibels.
		For sound sources that are large relative to the listener distance, the sound level falls off at less than the 6 dB-per-distance-doubling predicted by the inverse-square law.
		The bottom line is that the levels from the stage often force the levels produced by the mains to exceed the comfort limits of the audience.
	www.prosoundweb.com /lsi/tech/race/levels.php (1821 words)

	Sound Pressure Levels
		If we listen to a series of sounds having, what we perceive, a constant step in loudness the corresponding sound waves in fact have a multiplicative factor in their amplitudes.
		The sound pressure level is measured in decibels (dB) and is
		This last equation tells us that a sound pressure level increase of 20 dB corresponds to a factor of 10 increase in the amplitude of the sound waves.
	hep.physics.indiana.edu /~rickv/Sound_Pressure_Level.html (649 words)

	Sound Pressure
		The Sound Pressure is the force of sound on a surface area perpendicular to the direction of the sound.
		Sound is usually measured with microphones responding proportionally to the sound pressure - p.
		Decibel A, B and C The sound pressure is not equally sensed by the human ear at different frequencies.
	www.engineeringtoolbox.com /sound-pressure-d_711.html (487 words)

	Quest Technologies-Sound Level Meters \| Sound Pressure Level-Noise Level Measurement
		Sound level meters by Quest Technologies provide reliable and accurate sound level measurement, real-time octave-band frequency analysers, and environmental noise monitoring systems for risk and exposure assessment.
		Sound level meters (SLM) are one of the most reliable ways to measure noise levels.
		Sound level meters may or may not include weighting networks and the response time constant that is required under many ordinances.
	www.quest-technologies.com /library/sound_level_meters.htm (754 words)

	Sound Pressure Level (Site not responding. Last check: 2007-10-19)
		Sound pressure level is a measurement of the pressure of a sound in relation to a fixed reference point.
		Since the square of the sound pressure is proportional to the sound's intensity
		the equation for calculating sound pressure level is much the same as for sound intensity, only taking the square of the proportions.
	www.sfu.ca /sca/Manuals/ZAAPf/s/spl.html (70 words)

	Table chart sound pressure levels level sound pressure and sound intensity ratio calculation comparison - sengpielaudio (Site not responding. Last check: 2007-10-19)
		The sound pressure level decreases in the free field with 6 dB per distance doubling.
		The sound pressure in a free field is inversely proportional to the distance from the microphone to the source.
		The sound pressure is the force F in newtons N of a sound on a surface area A in m
	www.sengpielaudio.com /TableOfSoundPressureLevels.htm (577 words)

	Workplace Hearing: Hearing Conservation Services
		sound intensity varies inversely with the square of the distance from the source.
		Ambient noise is usually a composite of sounds from near and far sources none of which are particularly dominant.
		The effect of sound on an individual receiver is usually evaluated by measurements near the ear or close to the body.
	www.workplacegroup.net /hearing_equations.htm (982 words)

	Sound Power, Intensity and Pressure
		Decibel is a logarithmic unit used to describe the ratio of the signal level - power, sound pressure, voltage or intensity or several other things.
		Sound power is the energy rate - the energy of sound per unit of time (J/s, W in SI-units) from a sound source.
		Sound Intensity The sound intensity level is the acoustic power of a sound per unit of area in relation to a fixed reference.
	www.engineeringtoolbox.com /sound-power-intensity-pressure-d_57.html (394 words)

	Sound Pressure Level and Power
		Because of the wide range, sound pressure measurements are made on a logarithmic scale (decibel scale).
		SPL is proportional to the average squared amplitude.
		Two equal sources produce a 3 dB increase in sound pressure level, assuming no interference.
	ccrma.stanford.edu /CCRMA/Courses/152/SPL.html (105 words)

	FN P90 SOUND PRESSURE LEVEL COMPARISONS (Site not responding. Last check: 2007-10-19)
		Furthermore, the amount of pressure generated by the intemal spring during mounting is considerably less than some quick mounts I've used on other weapons, making the installation process easier and faster, without sacrificing security.
		While this is a very interesting design that produces a satisfying sound signature when fired with either supersonic or subsonic fodder, there is no substitute for rigorously evaluating the performance of a suppressor with repeatable and standardized scientific methodology.
		The sound signatures, which are more properly called sound pressure levels (SPLs), appear in Table I along with some comparative data for reference.
	remtek.com /arms/fn/p90/sp90 (2157 words)

	IEC Noise Prediction for Valves
		Image further that the applied force shown in the figure is a sinusoidal force created by the effect of the fluid sound pressure waves continuously bouncing off the wall of the pipe at some frequency determined by the frequency of the sound wave.
		The standard assumes that the noise level at the peak frequency is the most important and essentially ignores the noise level generated at other frequencies in the haystack spectrum.
		Since sound power level stays constant as it flows outward, the sound power level at each wave front surface is the same as any other, however, this power gets distributed over a larger and larger surface area as we get further and further from the source.
	www.iceweb.com.au /Technical/ValveNoise.htm (3721 words)

	Sound_Pressure_Level (Site not responding. Last check: 2007-10-19)
		The electroacoustic equivalent to SPL is measured with a
		Because the square of the sound pressure is proportional to
		Two SPL measurements in decibels may be combined with the aid of the following chart.
	www.sfu.ca /sonic-studio/handbook/Sound_Pressure_Level.html (207 words)

	sound pressure calibration (Site not responding. Last check: 2007-10-19)
		To determine what the actual air pressures were, you have to record an extra sound with a known air pressure, with the same recording gain as the rest of your recordings.
		It is best if this extra sound is something like a white noise, so that its sound pressure level can be determined reliably.
		A sine wave of 400 Hz, for instance, is less suitable, since its sound pressure level at your microphone can depend very strongly on the precise position and direction of the loudspeaker and on the position of other objects (like you, the experimenter) in the room (differences of 10 dB are no exception).
	www.fon.hum.uva.nl /praat/manual/sound_pressure_calibration.html (362 words)

	sound pressure level
		Reference pressure (a) is in general use for measurements concerned with hearing and with sound in air and liquids, whereas (b) has gained widespread acceptance for calibration of transducers and various kinds of sound measurements in liquids.
		Unless otherwise explicitly stated, it is to be understood that the sound pressure is the effective (root-mean-square) sound pressure.
		It is to be noted that in many sound fields the sound pressure ratios are not the square roots of the corresponding power ratios.
	www.webref.org /acoustics/s/sound_pressure_level.htm (354 words)

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