sound values calculator soundpressure soundpressure level sound intensity level - sengpielaudio
calculator soundpressure soundpressure level sound intensity level sound power sound energy density sound levels pressure Pascal Pa sound level calculation sound intensity level levels field energy size SPL decibel decibels dB dB-A dB-C dB-SPL air amplitude distance energy field value sound units dB law speed calculating spl calculate calculating calculations quantities calculator conversion compute tables sound studio technique techniques audio acoustics typical pressure levels calculations microphone formula values Sengpiel Berlin sengpielaudio
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Conversions and Calculations
Sound  Quantities and their Levels

Enter a value in the left or right box, then press the TAB bar or make
a mouse click at an empty space at the side, to get the solution.
The calculator works in both directions of the ↔ sign.

Sound pressure p:
Pa = N/m2		  ↔  Sound pressure level Lp:
dB-SPL
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Standard reference sound pressure p0 = 20 μPa or 2 × 10-5 Pa (0 dB)

Sound intensity I:
W/m2		  ↔  Sound intensity level LI:
dB-SIL
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Standard reference sound intensity I0 = 1 pW/m2 or 10-12 W/m2 (0 dB)

Sound power Pac:
W		  ↔  Sound power level LPac:
dB-PWL
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Standard reference sound power Pac0 = 1 pW = 10-12 W (0 dB)

Particle velocity v:
m/s		  ↔  Particle velocity level Lv:
dB-SVL
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Standard reference particle velocity v0 = 5 × 10-8 m/s (0 dB)

Sound energy W:
J = W·s		  ↔  Sound energy level LW:
dB-SWL
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Standard reference sound energy W0 = 1 pJ or 10-12 J (0 dB)   J = W·s

Sound energy density E:
J/m3 = W·s/m3		  ↔  Sound density level: LE
dB-SEL
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Ref. sound energy density E0 = 1 pJ/m3 or 10-12 J/m3 (0 dB) (W·s/m3)

Sound Field Quantities   :-)
Sound pressure, sound or particle velocity, particle displacement or particle ampltide, voltage, current, electric resistance.
 Inverse Distance Law 1/r		 Sound Energy Quantities
Sound intensity, sound energy density, sound power, electric power.
 
Inverse Square Law 1/r²

Since sound measuring instruments respond to sound pressure the "decibel" is generally associated with sound pressure level. Sound pressure levels quantify in decibels the intensity of given sound sources. Sound pressure levels vary substantially with distance from source, and also diminish as a result of intervening obstacles and barriers, air absorption, wind and other factors.
Sound Pressure Level (SPL): 20×log (p/p0) = 10×log (p/p0)², where  p0 = 2×10-5 N/m2.
p = root mean square sound pressure  (N/m2)
The usual reference level p0 is 20×10-6 N/m2. Note that the noise from motors is documented in sound power level. "Threshold of audibility'' or the minimum pressure fluctuation detected by the ear is less than 10-9 of atmospheric pressure or about  20×10-5 N/m2 (pascal) at 1000 Hz. "Threshold of pain'' corresponds to a pressure 106 times greater, but still less than 1/1000 of atmospheric pressure.  Because of the wide range, sound pressure measurements are made on a logarithmic scale (decibel scale).
Sound power levels are connected to the sound source and are independent of distance. Sound powers are indicated in decibel. Lw = 10 × log (P / P0) where:
P0 = reference power (W).
The usual reference level is 10-12 W, calculated from p0 = 20 micropascal, which is the lowest sound persons of excellent hearing can discern. Sound power is measured as the total sound power emitted by a source in all directions in watts (joules / second). Sound power levels do not vary with distance from source.

Questions: (The calculator above can help)
1. How many dB is the sound pressure of p = 1 Pa?
2. How many dB is the sound intensity of I = 1 W/m2?
3. How many dB is the sound power of P = 1 W?
4. How many dB is the particle velocity v = 1 m/s?
5. How many dB is the sound energy of W = 1 J?
6. How many dB is the sound energy density of E = 1 J/m3?

Table of Sound Levels, Sound Pressure, and Sound Intensity
Conversion of Sound Units (Levels)
Damping of Sound Level with Distance

Frequently used false statements in the context of sound sizes

Wrong expressions Correct version
Sound pressure decreases inversely as the square
of the distance increases with 1/r2 from the
sound source.		 Sound pressure decreases inversely as the
distance increases with 1/r from the sound source.
Sound pressure level decreases inversely as the
square of the distance increases with 1/r2 from the
sound source. 3 dB per doubling. 		Sound pressure level decreases by 6 dB per doubling
of distance from the source to 1/2 (50 %) of the sound
pressure initial value.
Sound intensity decreases inversely as the
distance increases with 1/r from the sound source.		 Sound intensity decreases inversely as the square
of the distance increases with 1/r2 from the sound
source.
Sound intensity level decreases inversely as the
square of the distance increases with 1/r2 from the
sound source. 3 dB per doubling. 		Sound intensity level decreases by 6 dB per doubling
of distance from the source to 1/4 (25 %) of the sound
intensity initial value.

Neither the sound power, nor the sound power level decreases in
doubling the distance up to a value or up to any dB. Why is this so?

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