An investigation of the parameters derived from the inverse filtering of flow and microphone signals

This paper is a part of a project concerning the finding of objective characteristics of susceptibility to voice strain. In that project, measurements were made of simultaneous recordings of microphone speech, oral flow, oral pressure and EGG. A comparison is made of parameters extracted from the inverse filtered waveforms of oral flow and speech pressure from these recordings, that is, with and without a face-mask. Microphone and flow recordings of the syllable /pæ/ were inverse filtered. The parameters speed quotient (SQ), open quotient (OQ), the amplitude difference between the first and second harmonic (H1-H2), and a measure of spectral slope were extracted from the glottal wave form. Initial analysis was intended to show a correlation between the parameter values for mask and non-mask recordings. The expected correlation was not forthcoming, and a re-assessment of the methodology was required. A repeated measures analysis of variance was then carried out to examine the effects of three independent variables: presence of the flow-mask, presence of an endoscope, and voicing condition. The results showed that the presence of the mask used for the flow recordings had a significant effect on the parameters which were examined. The explanation for these results include the psychological effect of the mask, inconsistent voicing strategies on behalf of the subjects, possible large within-speaker variation, and the acoustic effects of the flow mask.