Operation principle of vocoder

The input signal (your voice saying "Hello") is fed into the vocoder's input. This audio signal is sent through a series of parallel signal filters that create a signature of the input signal, based on the frequency content and level of the frequency components. The signal to be processed (a synthesized string sound, for example) is fed into another input on the vocoder. The filter signature created above during the analysis of your voice is used to filter the synthesized sound. The audio output of the vocoder contains the synthesized sound modulated by the filter created by your voice. You hear a synthesized sound that pulses to the tempo of your voice input with the tonal characteristics of your voice added to it.