Application Engineering Basics

Noise Facts

  • OSHA (Occupational Safety & Health Administration) regulates and monitors in-plant noise.
  • Allowable noise is a function of dBA level at certain distance over an exposure time.
  • OSHA regulations state 90 dBA for an 8 hour work period using slow responic setting on meter.
  • Adding a second noise producer of equal dBA will add 3 dBA to the first dBA reading.
  • Sound pressure level (SPL) decreases with distance (d)


    Therefore, each doubling of distance results in 6 dBA reduction.

Loudness Levels of Familiar Noises
(Approximate Average Including Ear Network)

L
O
U
D
N
E
S
S

L
E
V
E
L
S

I
N

D
E
C
I
B
E
L
S
 130覧



120覧



110覧



100覧



90覧



80覧



70覧



60覧



50覧



40覧



30覧



20覧



10覧



1覧 		Threshold of Painful Feeling

Airplane and Propeller at 10 Ft.





Train Passing at Hight Speed



Riveter at 30Ft. Auto Horn at 20 Ft.
Pneumatic Drill at 10 Ft.
Subway Train
Fire Siren at 75 Ft. Street Railway

Noisy Street
Police Whistle at 16 Ft. Auto at 60 MPH


Very Noisy Restaurant, Auto at 40 MPH
Average Stenographic Room

Factories, Auto at 20 MPH
Noise in Pullman (Windows Shut)
Noisy Office
Average Restaurant
Dept. Store, Average Conversation at 3 Ft.

Average Office, Quiet Street
Noisy Residence

Quiet Restaurant
Quiet Office
Museum
Average School
Average Residence
Picture Theater
Library Reading Rooms
Auditoriums
Average Whisper at 5 Ft.
Very Quiet Residence


Broadcasting Studio
Zero of A.I.E.E. Scale 14 Db.


Zero of Original Scale 8.5 Db.


Threshold of Audibility

 

Regenerative Blower Noise Chart* in dBA
* Average at 1 meter, 4 places around the blower

Model Mode Model Mode
Suction Pressure Suction Pressure 
SE 60-62 60-62 555 80-81 80-81
MF 64-65 64-65 656 82-83 82-83
RDC 76-78 76-78 6 85-86 85-86
SL2 69-72 69-72 707 83-85 84-86
SL4 72-78 72-78 808 84-85 84-85
SL5 76-79 76-79 623 81-82 81-82
101 65-67 66-68 S7 88-89 88-89
202M 67-69 68-70 858 84-85 84-85
303M 65-67 67-69 823 82-84 82-84
353M 72-73 73-74 S/P 9 90-91 90-91
404M 73-74 74-75 909 81-82 84-86
454M 76-77 75-76 1223 84-85 84-85
513 80-81 80-81 S/P 13 87-88 90-91
505M 77-78 76-77 14 86-87 86-87
523 82-83 82-83 S/P 15 91-92 91-92

dBA at Distance Converstion Chart

 

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