DS-2000 Frequently Asked Questions
Question number FAQ-0713
When the microphone was calibrated with the acoustic calibration device, the EU/V value became very high; why is that?
In DS-0221 and DS-0223, 0 dBVr corresponds to 1 Vr (where r indicates the effective value). The sound pressure of 0 dBspl is 20 μPa. To match dBVr to dBspl, it is possible by multiplying by a certain coefficient K.
This coefficient is
and
In order to achieve this, the value of EU/V becomes very large.
Supplementary explanation
The sound level in dB is set at 0 dB, which corresponds to 20 μP a (Pascals). If we denote the measured sound pressure (RMS) as P (P a), the sound pressure level A dBspl is expressed by the following formula.
 | （1） |
In DS-0221 and DS-0223, the input signal is voltage, so 0 dB is taken as 1 Vr (RMS). When the signal voltage is B (Vr), the dBVr value C is;
 | （2） |
A microphone is a sensor that converts sound pressure into voltage, so if the sensitivity of the microphone is K (V) per 1 Pa, the sound pressure P (P a) when the voltage signal is D (Vr) is;
 | （3） |
It can be obtained as follows. Substituting this into equation (1);
 | （4） |
Comparing the logarithms of equations (2) and (3);
 | （5） |
According to this, C (dBVr) equals A (dBspl). From this, the value of EU/V will be derived.
It can be seen that when set, C (dBVr) of DS-0221 and DS-0223 can be displayed as P (dBspl).
Last updated date: 2006-10-23