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04-01-2008 12:41 PM

I presently have a SAS dataset of audiograms with a numeric var named SPL. It contains values which represent sound pressure levels measured in decibels (dBSPL). I need to convert the values of SPL to sound pressure measured in Pa (Pascal) or __u__P (micropascals) and store the converted values for future analysis. Any idea how to help this novice do this in SAS?

Thanks

Thanks

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Posted in reply to deleted_user

04-02-2008 11:50 AM

I found this bye google searching the internet for

convert dbspl to pascal units

"'Pa' is the abbreviation for Pascal, which is a unit of pressure that is equivalent to 93.9794 dB SPL (Sound Pressure Level)."

so, the SAS statement is

Pa=93.9794*;

If you need to know how to save a pemanent SAS dataset, you probably need a short cours e on introductory SAS. Cody's book might be useful there.

convert dbspl to pascal units

"'Pa' is the abbreviation for Pascal, which is a unit of pressure that is equivalent to 93.9794 dB SPL (Sound Pressure Level)."

so, the SAS statement is

Pa=93.9794*

If you need to know how to save a pemanent SAS dataset, you probably need a short cours e on introductory SAS. Cody's book might be useful there.

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Posted in reply to deleted_user

04-02-2008 03:23 PM

Unfortunately its not that simple. This is decibled sound pressure with a reference pressure of 0.00002Pa, it is not a simple multiplicative conversion factor.

dbSPL = 20 * LOG10(Pa/0.00002)

So the conversion is going to be

X = Pressure in Pa

Y = Presseure in dbSPL

Y=20*LOG10(X/0.00002)

Y/20 = LOG10(X/0.00002)

10^(Y/20)=X/0.00002

X = 0.00002 * 10^(Y/20)

Or in SAS Functions

X = 0.00002 * (10**(Y/20))

Ike Eisenhauer

Message was edited by: WDEisenhauer

dbSPL = 20 * LOG10(Pa/0.00002)

So the conversion is going to be

X = Pressure in Pa

Y = Presseure in dbSPL

Y=20*LOG10(X/0.00002)

Y/20 = LOG10(X/0.00002)

10^(Y/20)=X/0.00002

X = 0.00002 * 10^(Y/20)

Or in SAS Functions

X = 0.00002 * (10**(Y/20))

Ike Eisenhauer

Message was edited by: WDEisenhauer

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Posted in reply to deleted_user

04-03-2008 04:57 PM

Thanks! I actually had the conversion coded as:

X = 20*(10**(Y/20))/1000000;

Same result, but your's looks cleaner.

X = 20*(10**(Y/20))/1000000;

Same result, but your's looks cleaner.