Ben,Do you have an SPL meter?
Play a constant test-tone or white/pink noise* and tell me the SPL reading and the Arduino's ADC reading. (We don't need to convert the ADC reading to voltage.)
Even with a constant test-tone, the ADC reading is going to jump-around a LOT because we are reading random places on the sound-wave. So try to pick-out the peak/maximum reading.Once we have an ADC reading that we can match to an SPL reading, I can help you with the calculations
which can be done in your sketch.
Once the basics are working, you can add some code to your sketch to pick-out the peaks and maybe average/smooth the peaks.
Has anyone of you guys made any progress and would be willing to share? I
I have NOT built an SPL meter, so I don't have a working sketch to give you. But I do have many years of experience with audio & electronics. I've built a couple of sound-activated lighting effects with the Arduino, and I have an SPL meter. One of the lighting effects I built is a "giant VU meter", but it's not calibrated in dB. In fact, it's intentionally uncalibrated because it automatically adjusts to changing loudness for lots of "meter action", no mater how loud the music is playing.
can create constant-noise, or test-tones that you can save as WAV or MP3.