Sound pressure level SPL meter...

Is there any SPL meter with Pascals scale in the market ? Or Android application ?

Is there any SPL meter calibrator application for Android that you may know of ?

Calibrator for a sound level pressure SPL meter ?

Is it possible to build a calibrator ? If home making one, how to calibrate such calibrator ? :roll:

Accurate calibration is difficult. The decibel scale is non-linear (that is, logarithmic). It may be easiest to make your meter respond in a linear fashion, however a linear scale shows an enormous difference between a whisper and a jet engine. It is possible to make your circuit as one logarithmic scale. Or instead you may decide to make several switchable ranges.

You may want to create two options regarding meter response: (a)make your meter so it responds immediately to every sudden burst of sound, or (b) make an averaging circuit which yields a smooth response covering the past second or two.

Your mic needs to be sensitive to a whisper, but also rugged so that it does not distort at painfully loud levels. You can see charts of the decibel scale, showing typical noise levels in daily life situations. I believe to mark your scale, the easiest way is to write figures on paper next to the needle. Or next to the led's. I have done that in the past.

In a past project I used high quality dynamic microphones and switched gain amplifiers (INA102) followed by RMS to DC converters to take accurate SPL measurements. A processor sent signals back to the INA102 to auto-range the gain. The resulting voltage could then be mathemetically converted to a dB range and a constant according to the selected gain added to it.

Calibration is difficult, I used an anechoic chamber and NPL calibrated source to set the reference levels.

Brian.