Parametric Talking MachineTo make the most economical use of available transmission bandwidths the fundamental structure and the information bearing elements contained in speech was determined with a machine (Parametric Artificial Talker) designed and built at SRDE.

By changing the voltages applied to the input, sounds resembling human speech were synthesised and displayed as two and three-dimensional speech patterns. When the voltages were varied to a pre-set pattern PAT uttered complete phrases and by varying the control signals comparatively slowly and passing them through a narrow band filter it was shown that speech could be transmitted with a bandwith of less than 100 Hz.

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