Converting dBV to dB SPL
The RZ6 Processor is a ±10 V device and so levels described in BioSigRZ are inherently interpreted as dB Volts. When the microphone, which converts mechanical energy to a voltage, is known; you can use the gain settings in the software to convert the dB Volts to display values in dB SPL.
For example, assume you have a peak of -97.48 dBV you'd like to convert. You can find the linear voltage with V = 10^(dBV/20) and then compare this to the Etymotic microphone response at 93.9 dB (.05) to get a dB value relative to 93.9, and then add 93.9. So the resulting equation is:
20 * log([10^(dBV/20)] / .05 + 93.9
For -97.48 dBV the output would be:
20 * log([10^(-97.48/20)] / .05) + 93.9 = 22.44 dB
The Acquisition Settings section discusses where to apply this type of conversion.
Notice that the starting dBV value +120 = 22.52, which is a close approximation to the actual value of 22.44 dB. So, when you are viewing a plot that uses dBV, you can use +120 to reach a quick approximation of the dB SPL.