Acoustical and perceptual cues of the palatalized articulation of /s/

Journal of the Acoustical Society of Japan, Vol. E-18, No. 6, pp. 297-304, 1997

Acoustical and perceptual cues of the palatalized articulation of /s/

T. Arai, K. Okazaki, S. Imatomi and Y. Yoshida

Abstract: Palatalized articulation (PA) is frequently observed in speech uttered by postoperrative cleft palate patients. Provided the acoustical and perceptual cues of PA can be found, speech therapists will be able to use these cues to diagnose PA non-invasively and objectively. We tested human perception of certain synthetic sounds to verify the cues of the PA of /s/ in Japanese. To synthesize the fricatives, we modified the center frequency and the bandwidth of a complex-conjugate pole pair of an all-pole filter obtained from the linear predictive analysis of the PA of /s/. First, we shifted the center frequency from 1,000 to 3,000 Hz, while the relative bandwidth, or Q factor, was fixed at 10. Subsequently, we shifted the Q factor from 1 to 10, while the center frequency was fixed at 1,800 Hz. The results of a perceptual experiment involving nine speech therapists were conclusive that fricatives having a peak between 1,600 and 2,400 Hz tend to be identified as the PA of /s/, and fricatives having a peak at 1,800 Hz with the Q factor > 5, tend to be identified as the PA of /s/. The two-tube model also showed that a peak around 2 kHz characterizes the PA of /s/.

Keywords: Cleft palate speech, Palatalized articulation, Acoustic analysis, Synthetic speech, Linear predictive coding

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