Analysis of non-stationary signals--Digital filters vs. FFT

Meaningful analysis of non-stationary signals such as speech, is normally implemented on mini-computers coupled to array processors. In contrast, this paper describes the use of dedicated, self-contained instruments for the simpler forms of analysis. A real-time, 1/3 octave digital filter bank coupled to an RMS detector with time constants down to 1/32 s is described as well as a unique FFT processor with a lo K input memory. Scan analysis permits seeing the running 1 K spectrum at different speeds. Addition of a small table top computer permits "scan" cepstrum for pitch extraction and formant analysis.