Sound pressure levels - sengpielaudio Google Page Rank
dB sound pressure table chart level levels dB decibel decible comparison calculator calculation calculations computation calculate calculation convert conversion factor ratio voltage power sound intensity sound reference value level acoustic velocity sound distance 1/r law electrical resistance voltage power ratio sound pressure level matching dBA dB SPL sound pressure intensity ratios field energy quantity quantities energy loudness sound energy density audio reference magnitude sound studio techniques acoustics volts volt watts watt sound pressure intensity sengpielaudio Sengpiel Berlin

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• Decibel Table - Comparison Chart •

Table of Sound Levels and corresponding
Sound Pressure and Sound Intensity - Units and Quantities

To get a feeling for decibels, look at the table below which gives values for the sound pressure levels of common
sounds in our environment. Also shown are the corresponding sound pressures and sound intensities.
From these you can see that the decibel scale gives numbers in a much more manageable range.
Sound pressure levels are measured without
weighting filters. The values are averaged and can differ ±10 dB.

Table of sound levels L and corresponding
sound pressure and sound intensity
Examples Sound Pressure
Level Lp dBSPL
Sound Pressure p 
N/m2 = Pa
Sound Intensity I 
W/m2
Jet aircraft, 50 m away 140 200 100
Threshold of pain 130 63.2 10
Threshold of discomfort 120 20 1
Chainsaw, 1m distance 110 6.3 0.1
Disco, 1 m from speaker 100 2 0.01
Diesel truck, 10 m away   90 0.63 0.001
Kerbside of busy road, 5 m   80 0.2 0.0001
Vacuum cleaner, distance 1 m   70 0.063 0.00001
Conversational speech, 1m   60 0.02 0.000001
Average home   50 0.0063 0.0000001
Quiet library   40 0.002 0.00000001
Quiet bedroom at night   30 0.00063 0.000000001

Background in TV studio

  20 0.0002 0.0000000001
Rustling leaf   10 0.000063 0.00000000001
Threshold of hearing     0 0.00002 0.000000000001

A given sound pressure level Lp in dBSPL without the measurement of the distance to the specific sound source is useless.

The reference sound for 0 dBSPL pressure is p0 = 20 µPa = 2 × 10-5 Pa, the threshold of hearing.
(The reference sound intensity is I0 = 10-12 W/m2.)
These values are not given as dBA, but as dBSPL, that means without any
weighting filter.

Level formula

Differentiate between sound pressure p as a "sound field quantity" and
sound intensity I as a "sound energy quantity".
I p2 for progressive plane waves.

The sound pressure level decreases in the free field with 6 dB per distance doubling. That is the 1/r law.
Often it is argued the sound pressure would decrease after the 1/r2 law (inverse square law). That's wrong.
The sound pressure in a free field is inversely proportional to the distance from the microphone to the source. p ~ 1/r.

Relation of sound intensity, sound pressure and distance law:

                       Intensity-distance
From this follows    sound pressure-distance
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Note: The often used term "intensity of sound pressure" is not correct.
Use "magnitude", "strength", "amplitude", or "level" instead.
"Sound intensity" is sound power per unit area, while "pressure" is a
measure of force per unit area. Intensity (energy quantity)
is not equivalent to pressure (field quantity).

dB scale for field quantities, like volts and sound pressures

dB pressure ratio - sengpielaudio
ratio

The sound pressure is the force F in newtons N of a sound on a surface area A in m2 perpendicular
to the direction of the sound. The SI-unit for the sound pressure p is N/m2 = Pa. p ~ 1/r.

Note: There is no conversion formula from dBA to dBSPL or vice versa.

How loud is dangerous?

190 dBA Heavy weapons, 10 m behind the weapon (maximum level)
180 dBA Toy pistol fired close to ear (maximum level)
170 dBA

Slap on the ear, fire cracker explodes on shoulder, small arms
at a distance of 50 cm (maximum level)

160 dBA Hammer stroke on brass tubing or steel plate at 1 m distance,
airbag deployment very close at a distance of 30 cm (maximum level)
150 dBA Hammer stroke in a smithy at 5 m distance (maximum level)
130 dBA Loud hand clapping at 1 m distance (maximum level)
120 dBA Whistle at 1 m distance, test run of a jet at 15 m distance
  Threshold of pain, above this fast-acting hearing damage in short action is possible
115 dBA Take-off sound of planes at 10 m distance
110 dBA Siren at 10 m distance, frequent sound level in discotheques and close
to loudspeakers at rock concerts, violin close to the ear of an orchestra
musicians (maximum level)
105 dBA Chain saw at 1 m distance, banging car door at 1 m distance (maximum level),
racing car at 40 m distance, possible level with music head phones
100 dBA Frequent level with music via head phones, jack hammer at 10 m distance
95 dBA Loud crying, hand circular saw at 1 m distance
90 dBA Angle grinder outside at 1 m distance
  Over a duration of 40 hours a week hearing damage is possible
85 dBA 2-stroke chain-saw at 10 m distance, loud WC flush at 1 m distance
80 dBA Very loud traffic noise of passing lorries at 7.5 m distance,
high traffic on an expressway at 25 m distance
75 dBA Passing car at 7.5 m distance, un-silenced wood shredder at 10 m distance
70 dBA Level close to a main road by day, quiet hair dryer at 1 m distance to ear
65 dBA Bad risk of heart circulation disease at constant impact
60 dBA Noisy lawn mower at 10 m distance
55 dBA Low volume of radio or TV at 1 m distance, noisy vacuum cleaner at
10 m distance
50 dBA Refrigerator at 1 m distance, bird twitter outside at 15 m distance
45 dBA Noise of normal living; talking, or radio in the background
40 dBA Distraction when learning or concentration possible
35 dBA Very quiet room fan at low speed at 1 m distance
25 dBA Sound of breathing at 1 m distance
0 dBA Auditory threshold

Conversion of sound units (levels)

Calculations of Sound Values and their Levels

Conversion of voltage V to dBm, dBu, and dBV

What is the threshold of pain?
You can find the following rounded values in various articles:

Sound pressure level Lp Sound pressure p
   120 dB 20 Pa
   130 dB 63 Pa
   134 dB 100 Pa
137.5 dB 150 Pa
   140 dB 200 Pa

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