A circuit to distinguish between sounds of different frequencies

hello guys
I am totally new to the world of robotics but am trying to build my 1st robo.
Please tell me how to make a circuit which can distinguish between 3 given sounds clips on the basis of frequency, amplitude or the sound itself prefarably without using a PIC because i dont know much programming.
Thanks.

I don’t have specifics for you, but,

I would think that a set of 3 op-amps/comparitors would allow you to find 3 different points. You should be able to select frequency or amplitude. Selecting sound, as in a particular tune or rythm would require a processor, in my mind.

It depends on how complex

It depends on how complex the sounds are. Do you have any examples?

If they are simple single fequency tones (e.g. a key press on a piano), then you could use a band-pass filter to isolate this.