Experimental evaluation of inverse filtering using physical systems with known glottal flow and tract characteristics.

The technique presented here uses an impedance head to measure the input impedance spectrum of a physical model of a vocal tract, and then to inject a known glottal flow waveform into the tract. The sound measured outside the mouth is used to evaluate inverse filtering techniques by comparison with the known glottal flow and measured acoustical properties of the tract. The normalized least square errors in the glottal flow were typically a percent or less in the time domain and several percent in the frequency domain. Accurate determination of resonance frequencies and bandwidths required a suitable order of inverse filter.