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Sound pressure level (SPL) or sound level Lp is a logarithmic measure of the rms pressure (force/area) of a particular noise relative to a reference noise source. It is usually measured in decibels (dB(SPL), dBSPL, or dBSPL). Wikipedia does not have an article with this exact name. ...
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. ...
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. ...
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 ξ) 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 logarithmic scale is a scale of measurement that uses the logarithm of a physical quantity instead of the quantity itself. ...
RMS may mean: root mean square, a concept in statistics and electronics Richard M. Stallman, a computer programmer and founder of the GNU project. ...
Pressure (symbol: p) is the force per unit area acting on a surface in a direction perpendicular to that surface. ...
The decibel is a dimensionless unit (like percent) that is a measure of ratios on a logarithmic scale. ...
 - where p0 is the reference sound pressure and p is the root-mean-square sound pressure being measured.
The commonly used reference sound pressure in air is p0 = 20 µPa (root-mean-square). 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. ...
In mathematics, root mean square (abbreviated RMS or rms) is a statistical measure of the magnitude of a varying quantity. ...
The pascal (symbol: Pa) is the SI unit of pressure. ...
In mathematics, root mean square (abbreviated RMS or rms) is a statistical measure of the magnitude of a varying quantity. ...
It can be useful to express sound pressure in this way when dealing with hearing, as the perceived loudness of a sound correlates roughly logarithmically to its sound pressure. See also Weber-Fechner law. Hearing, or audition, is one of the traditional five senses, and refers to the ability to detect sound. ...
The Weber - Fechner law attempts to describe the relationship between the physical magnitudes of stimuli and human perception of the intensity of stimuli. ...
Measuring sound pressure levels When making measurements in air (and other gases), 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 (roughly the sound of a mosquito flying 3 metres away). Thus, most measurements of audio equipment will be made relative to this level. However, in other media, such as underwater, a reference level of 1 µPa is more often used. [1] These references are defined in ANSI S1.1-1994. [2] In general, it is necessary to know the reference level when comparing measurements of SPL. The unit dB (SPL) is often abbreviated to just "dB", which gives some the erroneous notion that a dB is an absolute unit by itself. 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 pascal (symbol: Pa) is the SI unit of pressure. ...
Threshold of hearing is the sound pressure level SPL of 20 µPa (micropascals) = 2 × 10-5 pascal (Pa). ...
The American National Standards Institute (ANSI) is a private, non-profit standards organization that produces industrial standards in the United States. ...
Since the human ear does not have a flat spectral response, sound pressure levels are often frequency weighted so that the measured level will match perceived sound level. The International Electrotechnical Commission (IEC) has defined several weighting schemes. A-weighting attempts to match the response of the human ear to noise, while C-weighting is used to measure peak sound levels. [3] If the actual, as opposed to weighted, SPL is desired, many instruments allow a "flat" or unweighted measurement to be made. See also Weighting filter. A human ear An ear is an organ used by an animal to detect sound waves. ...
Sine waves of various frequencies; the lower waves have higher frequencies than those above. ...
The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ...
The A-weighting curve is one of a family of curves defined in IEC179 and various other standards for use in Sound level meters. ...
The A, B, C, and D weighting curves A weighting filter is used to emphasise some aspects of a phenomenon over others, for measurement or other purposes. ...
When measuring the sound created by an object, it is important to measure the distance from the object as well, since the SPL decreases in distance from a point source with 1/r (and not with 1/r2, like sound intensity). It often varies in direction from the source, as well, so many measurements may be necessary, depending on the situation. (An obvious example of a source that varies in level in different directions is a bullhorn.) This diagram shows how the law works. ...
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. ...
A megaphone is a cone-shaped device designed to amplify sound. ...
Examples of sound pressure levels | situation | sound pressure level dBSPL | | threshold of pain | 130 | | hearing damage during short term effect | from 120 | | jet, 100 m distant | 110–140 | | jack hammer, 1 m distant / Diskotheque | approx. 100 | | hearing damage during long-term effect | approx. 90 | | major road, 10 m distant | 80–90 | | passenger car, 10 m distant | 60–80 | | TVset at home level, 1 m distant | approx. 60 | | normal talking, 1 m distant | 40–60 | | very calm room | 20–30 | | leaves noise, calm breathing | 10 | | auditory threshold at 2 kHz | 0 | Threshold of hearing is the sound pressure level SPL of 20 µPa (micropascal) = 2 × 10-5 Pascal (Pa). ...
SPL in audio equipment Most audio manufacturers use SPL to describe the efficiency of their speakers. 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. Then a particular sound (usually white noise or pink noise) is played through the source at a particular intensity so that the source is consuming one watt of power. The SPL is then measured and the product labeled something like "SPL: 93 dB 1 W/1 m". This measurement can also be represented as a strict efficiency ratio of audio output (sound power) to electrical input (electrical power), but this is far less common. This method of rating speakers using SPL is often deceiving because most speakers produce very different SPLs at different frequencies of sound, often varying as much as ±10 dB throughout the speaker's usable frequency range (it generally varies less in higher quality speakers). The SPL quoted by the manufacturer is often an average over a particular range. // Definition The efficiency of an entity (a device, component, or system) in electronics and electrical engineering is defined as useful power output divided by the total electrical power consumed (a fractional expression). ...
For other uses of the term white noise, see white noise (disambiguation). ...
Pink noise ( (help· info)), also known as 1/f noise, is a signal or process with a frequency spectrum such that the power spectral density is proportional to the reciprocal of the frequency. ...
// Definition The efficiency of an entity (a device, component, or system) in electronics and electrical engineering is defined as useful power output divided by the total electrical power consumed (a fractional expression). ...
Sound power or acoustic power Pac is a measure of sonic energy E per time t unit. ...
See also 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 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. ...
Acoustics is a branch of physics and is the study of sound, mechanical waves in gases, liquids, and solids. ...
The sone is a unit of perceived loudness after a proposal of S. Smith Stevens in 1936. ...
The Weber - Fechner law attempts to describe the relationship between the physical magnitudes of stimuli and human perception of the intensity of stimuli. ...
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). ...
References - ↑ Underwater Acoustics — Federation of American Scientists
- ↑ Glossary of Noise Terms — Sound pressure level definition
- ↑ Glossary of Terms — Cirrus Research plc.
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