Sorry, I do not have enough time to get into your own project…

]]>can you give some idea to start,how to scale the frequency axis appropriately. Because 1/3 octave will have center frequency, lower frequency and upper frequency. Normally, we will got the bandwidth then we will apply bandpass filter (Butterworth Filter).

Then I found this:

http://www.mstarlabs.com/docs/tn257.html#Bands

but I don’t have any idea to start, if you can see the link, there are some related number of FFT bin with 1/3 octave..

Thanks

]]>I cannot see any reason why you could not do that, as long as you scale your frequency axis appropriately.

]]>From your PlainDSP code, can or not we evaluate the Decibels value using 1/3 Octave bands Filter:

http://www.sengpielaudio.com/calculator-octave.htm

and also A-weigthing

http://www.sengpielaudio.com/calculator-dba-spl.htm

http://www.engineeringtoolbox.com/decibel-d_59.html

Thank You

]]>You face the physical limitation of your input device. If the microphone is limited to 20kHz, use 20kHz as a sampling rate and you will be able to measure frequencies up to 10kHz.

For the same reasons, sounds from your CD are sampled at 44100Hz which is twice the highest frequency a man can detect. Most people will listen to frequencies as high as 16kHz, and this limit decreases over the time and depends very much on how loud you listen to music!

]]>Actually I’m confused regarding the microphone frequency and sampling frequency. I have the microphone with frequency range:

1) 100Hz – 10000Hz

2) 100Hz – 15000Hz

3) 20Hz – 20000Hz

For example I want to fully use the range of microphone frequency (20Hz – 20000Hz). From your link here (http://www.arduinoos.com/2010/10/sound-capture-cont/) you said:

“So that we may arbitrary decide to measure frequencies up to 10 kHz. Applying the Nyquist sampling theorem, we finally need to sample the wave signal at 20 kHz”

It is If I want to use until 20 Khz, I need to do the sampling frequency at 40KHz? It is true?

“const double _samplingFrequency = 40000.0;”

Thank You

]]>For the chip, I will go for it.. because I have the chip in my hand…

* So meaning that if my microphone capable until 10KHz, so we do sampling frequency at arduino code for 10KHz also, it is right?

Thank You

]]>Nice chip indeed: Rail to rail, from 2.5 o 5.5 Volts power supply, high slew rate, low noise, excellent bandwidth and it’s cheap, what else could you expect?

* One more answer …

Why would you measure signal at frequencies that your microphone cannot “hear”? Useless. Scanning from 0 to 10kHz will double the resolution of your frequency spectrum, and also take twice the time required to scan from 0 to 22kHz…

http://www.ti.com/lit/ds/symlink/opa344.pdf

* One more thing, if I have the microphone with frequency range 10-10000Hz, then we do a sampling frequency at 22100Hz.. it is we lost something?

Thank You

]]>Any general purpose silicon diode will do.

]]>