New Method for the Rapid Determination of Speech Frequencies

A new approach has been taken to the problem of rapid determination of the nature of sounds. The times between successive cycles of speech or other signals are measured, and the reciprocals of these time intervals are displayed on a storage oscilloscope. This results in an almost instantaneous presentation of frequency as a function of time, the readout of information lagging the acquisition of data by just a single cycle (a cycle is two successive zero crossings for purposes of this paper). A separate portion of the storage screen displays amplitude versus time. The patterns produced by the instrument look very similar to those of “visible speech” generated by other methods such as comb filters. Ultrasonic as well as audible frequencies are covered, up to 100 kHz. In these higher frequencies, the instrument has been used for the examination of bat and porpoise sounds.