So this is something i’m working on, on a sunday for my school design project 
@phec’s post about his beehive monitoring project helped me a lot.
The eventual end prototype is to have the Neopixel glowing as more conversation happens 
Stay tuned!
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Direct connection of the micro electret ?
Is the Spark doing some basic filtering
like an Envelope detector/follower ?
@bhamadicharef, not any but i have been reading about it yesterday.
Any suggestions on how i can achieve that? 
I see some FFT library ported but still trying to figure out how i can make use of it.
buffer some signal with small window size to make it a frame, multiply it with a classic window [1], apply the FFT on this windowed frame, this results in a vector with each value (called bin, typically of 2^N of them) correspond to the power within a frequency band … you can do some test with some sine waves.
I found this application note [2] interesting for what you want to do !
For e.g. one could use the online tone generator at [3] or even the Dual Tone Multi Frequency (DTMF) tones ! could be a nice application too for the Spark core !
Furthermore, the MSGEQ7 chip [4] from Mix-Sig is doing this with filters …
Have fun … will be joining soon !
Brahim
[1] http://en.wikipedia.org/wiki/Window_function#A_list_of_window_functions
[2] http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/CD00208762.pdf
[3] http://onlinetonegenerator.com
[4] https://www.sparkfun.com/datasheets/Components/General/MSGEQ7.pdf
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I know some others (including myself) have been wanting to learn more about FFT and how to implement:
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The DSP Lib with FFT, FIR and IIR filtering should be available at
https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Attachments/30831/um0585.zip
It is actually in assembler, maybe a bit hard to use. Should be optimized as from STMicroelectronics.
Brahim
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