Analysis of the Relationship between Palatal Contour and the Phonetic Function in Complete Denture Wearers Using a Speech Recognition System

Abstract

Individuals using dental prosthetic appliances tend to mispronounce the /S/ sound, phonation of which depends on the shape of the palatal contour. Thus, prosthodontists need to create the palatal contour in complete dentures with care. Here, we report that by using a speech recognition system, the palatal contour can be easily adjusted in the waxed denture base. AbstractPurpose: This study used a speech recognition system to investigate the intelligibility of the /S/ sound, which is based on the palatal contour of complete dentures. Methods:Six subjects with an edentulous maxilla participated in the study. The experimental dentures were made of self-curing acrylic resin and four curvatures (0, 2, 4, 6 mm) of the palatal contour were evaluated. A speech recognition program automatically converted the phonetic signals into phonetic segment labels. Labels that correctly recognized the /S/ sound were defined, and the distribution of the correct labels was analyzed in relation to the palatal contour. Palatograms were also recorded to assess tongue movement. Results: Repeated-measures one-way analysis ofvariance revealed a significant effect of the curvature of the palatal contour on the appearance ratio of the correct [Si] labels (F=53.1, P<0.05). Tukey's multiple comparisons revealed a significant difference between 0 mm and 2 mm (P<0.001), 0 mm and 4 mm (P<0.001), 2 mm and 6 mm (P<0.001), and 4 mm and 6 mm (P<0.001). Based on the appearance ratios of the [çi] labels, the 0 mm curvature of the palatal contour was rated as yielding the highest intelligibility (P<0.01), and based on those of the [tSi] and [dJi] labels, the 6 mm curvature was rated as yielding the intelligibility (P<0.01 for both). When tongue movement was assessed from the palatograms, tongue contact was found to be similar to that in the typical palatogram for each recognized syllable. Conclusion:The curvature of the palatal contour affects the pronunciation of the /S/ sound, and the appropriate curvature of the palatal contour in complete dentures for correct pronunciation of this sound is 2 to 4 mm.

Influence of Oral Morphology on Speech Production in Subjects Wearing Maxillary Removable Partial Dentures with Major Connectors

“…The speech evaluation system used in this study could assess leaks-in or closure of the vocal tracts by comparing tongue contact areas between the target and emerging sounds, thus identifying the incorrect labels [15, 27, 28]. In this study, the appearance of the [gi] sound as an incorrect label for [ki] significantly increased with the placement of an M-bar in low-palate subjects, compared with high-palate subjects.…”

“…The speech evaluation system (Voice Analyzer; Toshiba Digital Media Engineering Co., Tokyo, Japan) used speech recognition based on 213 types of integrated phonetic segments that represent phonetic features of transitions from one phoneme to another [27]. The flow process of this system is shown in Figure 2.…”

Influence of the Width and Cross-Sectional Shape of Major Connectors of Maxillary Dentures on the Accuracy of Speech Production

“…The speech evaluation system (Voice Analyzer; Toshiba Digital Media Engineering Co., Tokyo, Japan) uses speech recognition based on 213 types of integrated phonetic segments that represent phonetic features and features of transitions from one phoneme to another [30]. The acoustic analysis was performed using a fast Fourier transform that transformed the speech data of eight analytical frames (79 ms) into 64 ms of information (fast Fourier transform parameters).…”

“…In addition, this evaluation can be conducted immediately using only a laptop computer with specific software and a headset microphone. With this system, we tried to analyze the influences of the incisal overjet [29] and palatal contour [30] of a maxillary complete denture on alveolar consonants as well as the influence of the position of the major connector in a maxillary removable partial denture on several consonants, in addition to the alveolar consonants [31]. In particular, we found that locating the major connector in the middle area of the palate results in a smaller disturbance than in other areas from the viewpoints of accuracy of phonetic output, a shorter duration of consonants, and the tendency to change to other consonants.…”

Spectrogram Analysis of Complete Dentures with Different Thickness and Palatal Rugae Materials on Speech Production

“…Some patients had a remarkable adaptive capacity after repeating 5-6 key words. Analyzed spectrograms are different by frequency (low or high) of emitted sounds related to the denture changes and oral resonance cavity [ 17 ]. Specific letters were selected because not all the letters can be verified.…”