Sound Power
The definition of Sound Power Level and the Sound Power from some common
sources as fans, jet engines, cars, humans ....
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Sound Power
Sound power is the energy rate - the energy of sound per
unit of time (J/s, W in SI-units) from a sound source.
Human hearable Sound Power spans from 10-12 W to
10 - 100 W, a range of 10/10-12 = 1013.
Sound Power Level
Sound power can more practically be expressed as a relation
to the threshold of hearing - 10-12 W - in a logarithmic scale named
Sound Power Level - Lw:
Lw
= 10 log ( N / No) (1)
where
N
= sound power (W)
No
= 10-12 - reference sound power (W)
The table below indicates the Sound Power and the Sound
Power Level from some common (and some not so common) sources.
Source
|
Sound Power
- N - (W) |
Sound Power Level
- Lw - (dB) (re 10-12 W) |
Saturn Rocket
|
100,000,000
|
200
|
Turbo Jet Plane
Engine
|
100,000
|
170
|
|
10,000
|
160
|
Short exposure can
cause hearing loss
Inside jet engine test cell Jet Plane Take-off Military Jet Take-off from 30 meter |
1,000
|
150
|
Large centrifugal
fan, 800.000 m3/h
Turbo Propeller Plane at take-off Military jet plane at take-off 30 m |
100
|
140
|
Axial fan, 100.000 m3/h
Artillery Fire at 3 m Machine Gun Large Pipe Organ |
10
|
130
|
Deafening, Human
pain limit
Large chipping hammer Siren at 30 m Symphonic orchestra Jet Plane from passenger ramp Heavy Thunder Sonic Boom Small aircraft engine |
1
|
120
|
Threshold of
Discomfort
Large aircraft 150 over head Centrifugal van, 25.000 m3/h Accelerating Motorcycle Heavy Metal, Hard Rock Band Music Blaring radio Chain Saw Wood Working Shop Large air Compressor |
0.1
|
110
|
Very Loud
Air chisel Subway Steel Wheels Magnetic drill press High pressure gas leak Banging of steel plate Drive gear Car at Highway Speed Normal Fan Vacuum Pump Banging Steel Plate Wood Planer Air Compressor Propeller Plane Outboard motor Loud street noise Power Lawn Mover Helicopter |
0.01
|
100
|
Cut-off saw
Hammer mill Small air compressor Grinder Heavy diesel vehicle Heavy city traffic Lawn mover Maximum sound up to 8 hour (OSHA1) criteria - engineering or administrative noise controls) Jackhammer at 15 m Bulldozer at 15 m Airplane Cabin at normal flight Kitchen Blender Spinning Machines Pneumatic Jackhammer |
0.001
|
90
|
Loud - Intolerable
for Phone Use
Maximum sound up to 8 hour (OSHA criteria - hearing conservation program) Pneumatic tools at 15 m Alarm clock Buses, trucks, motorcycles at 15 m Dishwasher |
0.0001
|
80
|
Loud - Voice conversation
0.3 m
Car at 15 m Vacuum cleaner at 3 m Toilet Flushing Printing Press Inside Railroad Car Noisy Office Freight Train at 30 m Inside Automobile Clothes Dryer Vacuum Cleaner |
0.00001
|
70
|
Loud - Unusual
Background,
Voice conversation 1 m
Large department store Busy restaurant or canteen Ventilation Fan Noisy Home Average Office Hair Dryer |
0.000001
|
60
|
Moderate
Room with window air conditioner Office Air Diffuser Quiet Office Average Home Quit Street |
0.0000001
|
50
|
Voice, low
Small Electric Clock Private Office Quiet Home Refrigerator Bird Singing Ambient Wilderness Agricultural Land |
0.00000001
|
40
|
Noticeably Quit -
Voice, soft whisper
Room in a quiet dwelling at midnight Quiet Conversation Broadcast Studio |
0.000000001
|
30
|
Rustling leaves
Empty Auditorium Whisper Watch Ticking Rural Ambient |
0.0000000001
|
20
|
Quietest audible
sound for persons under normal conditions
Human Breath |
0.00000000001
|
10
|
Threshold of Hearing
Quietest audible sound for persons with excellent hearing under laboratory conditions2) |
0.000000000001
|
0
|
1) OSHA - Occupational Safety and Health Act -
The OSHA criteria document reevaluates and reaffirms the Recommended
Exposure Limit (REL) for occupational noise exposure established by the
National Institute for Occupational Safety and Health (NIOSH) in 1972.
The REL
is 85 decibels, A-weighted, as an 8-hr time-weighted average (85 dBA as an 8-hr
TWA). Exposures at or above this level are hazardous.
2) The reference level - 10-12 - for
the decibel
scale.
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