DS-2000 Frequently Asked Questions
Question number FAQ-0713
When I calibration the microphone with an acoustic calibration, the EU/V value was very high. Why is that?
In DS-0221 and DS-0223, 0 dBVr corresponds to 1 Vr (where r represents the RMS value). 0 dBspl of sound pressure corresponds to 20 μPa. To match dBVr to dBspl, a certain coefficient K is multiplied.
This coefficient
and
Therefore, the EU/V value becomes very large.
【supplementary explanation】
The dB value of sound level is such that 0 dB corresponds to 20 μPa (Pascals). If the measured sound pressure (effective value) is P (Pa), 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 value). The dBVr value C when the signal voltage is B (Vr) is:
 | （2） |
A microphone is a sensor that converts sound pressure into voltage, so if the microphone's sensitivity is K(V) per 1 Pa, then the sound pressure P(Pa) for a signal with voltage D(Vr) is:
 | （3） |
This is how it is found. Substituting this into equation (1), we get:
 | （4） |
Comparing the logarithms in equation (2) and equation (3):
 | （5） |
For this, C(dBVr) = A(dBspl). From this, the value of EU/V
By setting this, you can see that the C (dBVr) of DS-0221 and DS-0223 can be converted and displayed as P (dBspl).
Last updated: 2006-10-23