Do I need to use 2 sound sensors to detect the sound signals? If yes, can the sensors be connected directly in the circuit? or do I need to use an Arduino card and program it? Instead of the the sensors can I use small microphones and a loud speaker for the output? The entry of the sound signals to the circuit is essentially what I cannot solve.

Please note that I am in 2nd grade of Licence in Electrical-Electronics Engineering and this is my first homework. So I think that it has to be a simple thing. We studied about OP AMP s too and I think I need to use 2 (a summing and an inverting). What do you think?