Please Help - What is dB (A) ??

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Please Help - What is dB (A) ??

Postby Me » Mon Aug 09, 2004 8:51 pm

Can someone please help me? I need to know what dB (A) stands for. The context is: Sound Power Level - 86 dB (A) and Sound Pressure Level - 66dB (A). Does anyone have any ideas? Thanks!!
Me
 

Re: Please Help - What is dB (A) ??

Postby Knight » Mon Aug 09, 2004 8:55 pm

Me wrote:Can someone please help me? I need to know what dB (A) stands for. The context is: Sound Power Level - 86 dB (A) and Sound Pressure Level - 66dB (A). Does anyone have any ideas? Thanks!!

The human ear is more sensitive to sound in the frequency range 1 kHz to 4 kHz than to sound at very low or high frequencies. A higher sound pressure is therefore acceptable at lower and higher frequencies.

This knowledge is important in acoustic design and sound measurement. To compensate for the human ear, sound meters are normally fitted with filters adapting the measured sound response to the human sense. Common filters are dB(A), dB(B), and dB(C).

The decibel A filter is widely used. dB(A) roughly corresponds to the inverse of the 40 dB (at 1 kHz) equal-loudness curve for the human ear.

Using this filter, the sound level meter is less sensitive to very high and very low frequencies. Measurements made with this scale are expressed as dB(A).

The decibel C filter is practically linear over several octaves and is suitable for subjective measurements at very high sound pressure levels. The decibel B filter is between C and A. The B and C filters are seldom used.
William J. Knight
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Los Alamos National Labs
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Thank you!

Postby Me » Mon Aug 09, 2004 8:59 pm

Thanks very much!
Me
 


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