Noise
Rules ofThumb
Emissions Devices & Acoustic Silencing Various emissions reduction technologies are applied to exhaust systems to meet new emissions standards. The additional components can significantly change or eliminate the traditional acoustic silencing components common in older muffler designs. Depending on the application, emissions reduction devices may totally eliminate the need for further sound control and for others, minimal acoustic silencing may be required. The sound attenuation of emissions devices varies depending on the filtering substrates and configuration of the overall system.
Combining Two Equal Noise Sources Increases Sounds Level by 3 dBA Two equal noise sources combine to create a sound level 3 dBA greater than either source.
83 dBA
83 dBA
86 dBA
Twice the Loudness is a 10 dBA Increase The increases are not linear! Increasing noise by 10 dB sounds twice as loud.
Typical emissions aftertreatment substrates (ceramic and metal)
Familiar Sounds on the dBA Noise Scale Other examples of sound levels: 70 dB Traffic jam; 90 dB Heavy machinery, 130 dB Jet engine at 10 meters.
80 dBA
70 dBA
Threshold of Pain
Siren (100 feet)
140 130 120 110 100
Jet Plane (50 feet)
Automobile Horn (3 feet)
Chain Saw (50 feet)
Sound Pressure Level Changes With Distance Doubling the distance to a noise source decreases its sound level by 6 dB. Halving the distance to a noise source increases its sound level by 6 dB.
Commercial Airliner (inside)
Motor Cycle (50 feet)
90 80 70 60 50 40 30 20 10 0 dBA
Snowmobile (50 fet)
ruck
Over Road T (50 feet)
Conversation (3 feet)
Business Office
Soft Whisper (4 feet) 5
5 feet =1,5 m 3 feet = 1 m 10 feet = 3 m 20 feet = 6 m 50 feet = 15 m 100 feet = 30 m
6 dBA Decrease
10 Feet 86 dBA
20 Feet 80 dBA
Recording Studio
Threshold of Hearing
6 dBA Increase
6 t Medium- and Heavy-Duty Exhaust Products t 72
www.donaldson-filters.com www.donaldsonoemfiltration.com/technologies/emission
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