A speech-waveform correlator with magnetic-tape delay and electronic multiplication

The paper describes an instrument designed to compute the auto- and cross-correlation functions of speech sounds having a duration not exceeding 10 sec.The instrument comprises a twin-channel magnetic-tape delay and storage system, an electronic computor and certain ancillary apparatus. Analogue representation is used throughout, and the computed function is plotted automatically by a recording milliammeter.By recording at tape speeds faster or slower than normal, the operating range of 200–20000 c/s can be scaled up or down as required. It follows, therefore, that the instrument may be of use in a number of applications other than speech analysis.Details are given concerning the design of the instrument, its operation, and the accuracy of computation. In general, an accuracy of ±2% or better can be replied upon.A few recorded correlograms are given, and a table of correlation transforms is appended for use in testing the instrument.