# 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.

The Acquisition Settings section discusses where to apply this type of conversion.

For example, assume you have a peak of -70 dBV you'd like to convert. You can find the linear voltage with V = 10^(dBV/20) and then compare this to the microphone response at 93.9 dB to get a dB value relative to 93.9, and then add 93.9.

The TDT DPM1 microphone response at 93.9 dB is 0.6 V.

`20 * log10(10^(dBV/20) / 0.6) + 93.9`

For -70 dBV the output would be:

`20 * log10(10^(-70/20) / 0.6) + 93.9 = 28.34 dB`

Tip

Notice that the starting dBV value + 100 = 30, which is a close approximation to the actual value of 28.34 dB. So, when you are viewing a plot that uses dBV, you can add 100 to the dBV value reach a quick approximation of the dB SPL.