The sound pressure level of 0dBVr is considered as 1Vr (r stands for effective value) in the DS-0221 and DS-0223. Also, the sound pressure of 0dBspl is considered as 20µPa. To adjust the value of dBVr to dBspl, multiply the coefficient K to it.

 

This coefficient are and , so the EU/V value which is obtained by the multiplication becomes very large.

 

[Supplement]

The sound level of 0 dB is 20µPa (Pascal). When the measured sound pressure (effective value) is set as P (Pa), the sound pressure level A dBspl can be obtained by the following formula.

 

 

The input signal from the DS-0221 or DS-0223 is voltage, so 0 dB is obtained as 1 Vr (effective value). When the signal voltage is B (Vr), the dBVr value of C can be obtained by following formula.

 

 

The microphone is the sensor to convert the sound pressure to voltage, so when the microphone sensitivity of 1 Pa is set as K (V), the sound pressure P (Pa) of the voltage D (Vr) signal can be obtained as follows.

 

 

Substitutes the above to the formula (1).

 

 

C (dBVr) = A (dBspl) can be obtained when the logarithms of formula (2) and (3) are compared as follows.

 

 

From the above, when is set as EU/V value, the sound pressure C (dBVr) of DS-0221 and DS-0223 can be calculated and displayed as a voltage of P (dBspl),