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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 |
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| 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.
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:
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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
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 |
| 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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