Ok.. I have thought up a great project idea, but I am not sure if an arduino would be up to the task. Basically, I'd like to analyze audio input and have LEDs flash in "synch".
My question is, if run through the proper RC filters to isolate a particular range (say bass guitar), could the arduino "hear" audio and be like "oh, that's and E note. Now it's an A"?
If not, any ideas of how to go about it? I could use a PC/usb serial solution, but I'd like to make it standalone...
Check out this blog:
I hope, bass guitar is easy instrument compare to ground acoustic piano.
Sweet! Thank you for pointing that out. So now I know it can be done. Now to research the "how". Again, thank you. If I get anywhere, I'll post a final project in about a week 
look into Fast Fourier Transform - it might help with what you are looking for.
Now to research the "how"
Try your search from the link, there is a code you can download, with FFT implemented in.