Real-time FFT of the audio signal from a microphone?

[cvanc]

Hi all-

Let's say I want to see a FFT of the signal being picked up by a microphone.  And let's say I want to do this in real-time or nearly real-time.  I want to see changes as I move the microphone around.

How would you do this?  Especially, how would you best do this given constraints on cost and size?

I know you could always use some vintage piece like a spectrum analyzer, fed with the amplified signal from the microphone.  But is there a more modern, smaller, less expensive way to do this?

Thanks.

[hendorog]

There are plenty of apps on the Google App store which real time FFT on the mic (I guess they would also work on an external mic). No idea about IOS.

[wn1fju]

Do you have a laptop?  Plug the microphone into the microphone jack.  Then...

There must be a few dozen FFT Audio Analyzer programs, many of which are free, for download.  Google it.

I've used Spectran (www.weaksignals.com) in the past and it is great.  Don't know how current the author has kept it although.

[DavidDLC]

cvanc

If you want to do this with electronics, I have PCB for a SMD LED matrix that is designed for this purposes.

I made the PCB to replace a damaged LED matrix on a old equalizer.

Let me know

David DLC

[awallin]

gnu-radio probably has the bits and pieces to build scope/FFT/waterfall etc. displays quite easily from an audio source:
something along those lines: https://wiki.gnuradio.org/index.php/Guided_Tutorial_GRC

[alsetalokin4017]

You could do it in software or in single-chip solutions.
Google or search YouTube for "arduino color organ" for many examples of software implementations of FFT with mic input and color LED outputs. Looking at the associated sketch and schematic files will show you how FFT is implemented in c++ on a microprocessor, and how to turn condenser mic output into something that makes sense to the processor.
Or look for graphic equalizer display chips like MSGEQ7 for single-chip solutions.
With software you can select frequency bands and make up your own display modes like with addressable RGB LEDs, get really fancy if you like.
The single-chip solutions are more limited -- you get seven fixed frequency bands with the MSGEQ7 I think but it's cheap.

[ebclr]

If you don't want to reinvent the well

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR0.TRC0.A0.H0.Xaudio+spectrum.TRS5&_nkw=audio+spectrum&_sacat=0

[MikeP]

 I have been using REW for many years. Microphone with ADC from MiniDSP - Umic.

[The Soulman]

There a many programs to choose from, I often use visual analyzer, not the most stable but about every setting can be tweaked.
 
http://www.sillanumsoft.org/

It will work with any audio input device that works with windows.

[trobbins]

I use the Spectrum Analyser app on my phone - can help you tell the difference between mains frequency hum, and twice that frequency