Palatalized Articulation of [s] Sounds Using Synthetic Speech

Abstract

Using several models for synthesizing speech, we tested human perception of certain synthetic sounds to verify already published characteristics of palatalized articulation (PA) . In the mono-syllable [sm] uttered with normal articulation, part of the fricative sound [s] was replaced by synthetic noise. The following three models were used to synthesize [s] . The first model is a bandpass filter which has a pass band in a specific frequency range. The cutoff frequencies were shifted in intervals from low to high, while the bandwidth was fixed. The second model is an all-pole model with second-order linear predictive (LP) analysis. To implement this filter partial correlation (PARCOR) coefficients were used. The frequency of the Poles was shifted in intervals from low to high. The third model is an all-pole model using higher order LP analysis for a typical PA of [s] . Each filter is excited by white noise to synthesize the fricatives. The hearing discrimination of nine speech therapists formed the data for the perceptual experiment ; they were each requested to indicate what they heard. Their replies were categorized as : “ [s] ”, “ [∫], ”“ the PA of [s], ”or“other”. From the results we concluded: 1) the first model is not appropriate for synthesizing the PA of [s] ; 2) fricatives, which have a peak in the range of 2-3kHz, tend to be identified as the PA of [s] when synthesized by the second model : and 3) fricatives synthesized by the third model uning sixth or higher order LP tend to be identified as the PA of [s] .