Operation of the circuit. This circuit, an IC, a number HT82231 IC package that has other audio source animals. The origin of the sound depends on the switch S1-S8 of switch.
Each is a different animal sounds and choose to press each LED1, LED2 lights alternately as it sounds they hear. The R1, R2 LED forward current limiting for each signal will come out on pin 19, to expand the force with Q1. There is also a sound that VR1 can be adjusted as soon as we hear. Or slow as you like C1, C2 prevents low-frequency noise. And high frequencies.