A feedback control system for real-time formant estimation. II. Analysis of a hysteresis effect and F2 estimation

For pt.I see ibid., vol.40, no.9, pp.886-91 (1993). The feedback control system behavior is analyzed for an input signal composed of two sinusoids. If the frequency difference between the two input spectral lines is sufficiently great and the amplitude ratio is within certain limits, a hysteresis effect occurs. Then the system shows a tendency to select one of the two input spectral lines. The existence of the second line has only little influence on the accuracy of the detection of the selected line. From the analysis, conclusions of the system behavior regarding formant estimation can be drawn. A design example for second formant detection is simulated and compared with the results obtained by simulation of a zero-crossing system for F2 estimation and linear predictive coding (LPC) analysis.