A Real‐Time Speech Input System for a Digital Computer

In order to take best advantage of the speed and flexibility of the digital computer as a research tool in speech analysis and recognition studies a real‐time input system is needed. Such a system, which makes power‐spectrum data directly available to the computer, has been constructed at the Lincoln Laboratory for use with the TX‐0 and TX‐2 computers. A speech signal is fed to 35 band‐pass filters covering the range 100 to 10000 cps. The output of each filter is envelope‐detected, and the envelopes are sampled periodically by a 128‐position mercury commutator switch. The output of the commutator is converted to binary digital form and fed directly to the computer, At present the system is capable of making 7620 samples per second with a signal‐to‐noise ratio of over 40 db (7 bits). The filters, made up of high‐pass and low‐pass sections in cascade, can be connected to give a variety of band widths and center frequencies Patch‐cord connections between envelope‐detector outputs and commutator inputs permit...