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Old March 2nd, 2010, 10:32 AM   #1
Rob S.
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Dog The difference between dB and dBA ?

I am getting sound samples around the plant to install a
public address system . I am curious , what is the difference
between dB and dBA ,in simple terms ? The meter I used displays it anywhere from 84 to 98 dBA around the plant.

Thanks, have a great day.
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Old March 2nd, 2010, 10:43 AM   #2
tim2
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The dBA is referenced to some sound pressure level (not sure what it is thoug). When I worked alot with RF, dbm was the measurement. It's just dB refereced to one milliwatt. If you don't reference it to something a dB is just a ratio.
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Old March 2nd, 2010, 10:44 AM   #3
Steve Bailey
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http://lmgtfy.com/?q=what+is+the+dif...een+dB+and+dBA
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Old March 2nd, 2010, 12:50 PM   #4
L D[AR2,P#0.0]
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Could you repeat that please ?
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Old March 2nd, 2010, 12:50 PM   #5
leitmotif
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Quote:
Originally Posted by Rob S. View Post
I am getting sound samples around the plant to install a
public address system . I am curious , what is the difference
between dB and dBA ,in simple terms ? The meter I used displays it anywhere from 84 to 98 dBA around the plant.

Thanks, have a great day.
Way back when the phone company needed to figure out how to design speakers in phones that would be most compatible with how people hear. So they measured how people hear different frequencies. That data is the foundation today for all human speech and hearing measurements and designs and standard setting. It has been added to of course.

So as a result of all this there are three decibel scales
A B and C. The A scale is weighted to closely match human hearing. Some noise instruments have all three scales.
The A scale is the one all human noise exposure standards are set. As an industrial hygienist I never used B or C and have forgotten their purpose.

For your application I would recommend using the A scale.

Dan Bentler
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