a system for converting known speech segments into machine storable binary signals for the purpose of later attempting a match between a stored signal and an incoming signal using autocorrelation techniques . through the use of a clipper and a sample and hold register , the system converts an incoming speech signal into a bit stream signal . two successive groups of bits called frames are stored in separate registers . a bit - by - bit correlation is performed on the bits stored in the separate registers and a counter is indexed as a function of the correlation . a memory is provided for maintaining a record of the counts associated with each speech segment for later attempting computer pattern matching against received unknown speech segments .