1. A speaker recognition system for identifying a speaker and verifying registration of a speaker based on an input voice, comprising: a voice input section for inputting a voice; a preprocessing section for extracting a feature quantity from said inputted voice and averaging said extracted feature quantity timewise; a layered neural network for performing a predetermined operation based on an input pattern from said preprocessing section; and a speaker judgment section for judging identification or registration of said speaker based on an output from said neural network; wherein said preprocessing section divides said inputted voice into a plurality of frames that are timewise equal to one another, extracts a feature quantity for each frame, and averages together said feature quantity of each frame over a group of frames, thereby producing an input pattern for said layered neural network consisting of an extracted feature quantity which is timewise averaged.