Has anyone of you guys made any progress and would be willing to share? I
I wonder if I could use it in silent rooms like the ones in hospital where the sound level should be around 30dB.
That would depend on the quality of your analog electronics. ...I'm pretty sure the hospital rooms I've been are louder than 30dB SPL.
All I need to do is connect the Electret Microphone (https://www.sparkfun.com/products/9964) on my Arduino and do the programming, since it comes with a amplifier, right ?