Many thanks for such as detailed response and I should have add some more detail on the potential project. I have always been interested in sound and understand sound patterns & wanted to build an FFT box so understand & play with FFT analysis. It's something that I have read, but don't truly understand it all without building, testing and understand full how the whole system works. So it's really a research project and to help me understand more about FFT sound analysis.
The initial idea is just to make up the Teensy 3.1 audio board and log room data & generate sounds in the room which I can pick up and then ideally work out if it's possible to identify sounds such as doors, windows been open & closed, people walking around etc.
I have been using different microphones on an arudino project, such as the adafruit electret and a mems microphone and seeing the different types of response.
https://www.adafruit.com/product/1063
http://skpang.co.uk/catalog/breakout-board-for-admp401-mems-microphone-p-773.html
Thanks for the explanation and I suppose to be honest I not sure what is the end results i.e. just a number relating to a sound level or number in dB's? Does it really matter, higher number is louder and smaller number is quieter. As for accuracy, I think the mems microphone will be much better than the electret i.e. larger freq response and higher sensitivity.
What I am trying to do is work on a setup, something like this
- Sound generator at X distance from microphone, generating Y tone
- Measure the signal amplitude at the microphone amp i.e. feeding into the Teensy 3.1 audio board
- Adjust the microphone amp to a single of 2.83Vp-p which would provide 1.0 in the FFT software
- Repeat for different frequencies to understand the complete freq range response & add temperature/time factor
Question: what should be the distance and freq? Just researching sound meter calibration, I am sure I have read it's a 1khz sound at 1 meter from the microphone.
There are so many factors to understand, so it's breaking it down into little bits and then build up complete knowledge of the whole systems.