Converting dB to acceleration

[151079]

Hello
I recently measured vibration with a sound level meter (Norsonic 121 and accelerometer). The sound level meter only shows me values in dB. Can anyone tell my how I can convert the values to acceleration (or displacement)?
Thank you for your help.

 

[GregLocock]

You need to know the reference level of the dB calibration. Typically sensible people use 1g=0 dB, or 1 m s-2 = 0 dB.

Sadly there are many more standards than that.

Once you know this then
acceleration = Accref*10^((dB-dBref)/20)

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[BobM3]

The input amplifier specs for that meter list a range of .3 uV to 7 volts RMS. The specs call this a dB range of -10 to +137. Using this info I come up with a reference voltage level of approx .95 uVolts. You'll need to find out what the volts/g's is for your accelerometer. So for an example, if your accel puts out 1.9 uVolts at 1 g then the meter would show:

dB = 20 log (1.9E-06/.95E-06) = 6 dB

So an accel of 1 g would read 6 dB.

There appear also to be different gain ranges for the meter. You'll need to take those into account also.

Make sure the electrical guys here check my numbers!!