Sound Power

The definition of Sound Power Level and the Sound Power from some common sources as fans, jet engines, cars, humans ....

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 - L_w:

L_w = 10 log ( N / N_o) (1)

where

L_w = Sound Power Level in Decibel (dB)

N = sound power (W)

N_o = 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 - L_w - (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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