Audio Sensor - Does one exist?

[wojo1086]

I was wondering if there was an audio sensor that existed for the raspberry pi that could detect changing levels in frequency. My goal is to get some lights dancing to music using the raspberry pi.

[redhawk]

Not that I'm aware of, however you could construct an electronic circuit with band pass filters to detect certain ranges of frequencies, then provide a TTL output (of 3.3v) to the Pi's GPIO pins.

Richard S.

[toxibunny]

I kindof doubt it, but I also think one would be fairly easy to build. Have a look at stuff from here: http://www.discovercircuits.com/C/color-org.htm - and try to figure out how to interface it with the GPIO...

edit: beaten to the punch!

[techpaul]

Look at circuits and software to DTMF (Dual Tone Multi Frrequency) how different frequencies are used to pass telephone numbers over analog phone systems to an exchange or similar (push 1 for ....)

That should give you some ideas you expand to different frequencies.

[pimania]

I'm going to be building a couple of these for just such a task:

http://www.scary-terry.com/more_stuff/t ... onedet.htm

It looks fairly straightforward. I'll then need to write a bit of Python or grab some learnin' from Adafruit:

http://learn.adafruit.com/adafruits-ras ... uring-gpio

Keeps me busy...

j

[MarkR]

I've got a project where I'm using a USB microphone to detect sound. I then use the "arec" program from ALSA to convert it into a binary stream, and pipe it into a Python program.

I use numpy to get the data in chunks into an array, then use the FFT algorithm to measure the amplitude in various frequency bands. I do this on 250ms chunks of data, so the latency is at least 250ms, although you could use smaller.

The Pi only uses about 15% CPU doing this - completely in software in not-very-optimised python (albeit using numpy for the numerical analysis)

Does that sound like what you wanted to do?

Mark

[More Pi Please]

Does that sound like what you wanted to do?

I'm very interested in this : P


But I just need basic amplitude. No frequency stuff needed

If a noise is above a certain level I would like to use it in python.

[cudofcow]

retrofit a "Clapper"?

[More Pi Please]

I thought it would be easy to find some i2C audio sensor for the Pi

[toxibunny]

Use a USB sound card and a microphone

...or just Google 'i2c microphone' if you really want i2c...