Effects of tongue position in the simplified vocal tract model of Japanese sibilant fricatives /s/ and /ʃ/

Spectral analysis of strident fricatives in cisgender and transfeminine speakersa)

The spectral features of /s/ and /ʃ/ carry important sociophonetic information regarding a speaker's gender. Often, gender is misclassified as a binary of male or female, but this excludes people who may identify as transgender or nonbinary. In this study, we use a more expansive definition of gender to investigate the acoustics (duration and spectral moments) of /s/ and /ʃ/ across cisgender men, cisgender women, and transfeminine speakers in voiced and whispered speech and the relationship between spectral measures and transfeminine gender expression. We examined /s/ and /ʃ/ productions in words from 35 speakers (11 cisgender men, 17 cisgender women, 7 transfeminine speakers) and 34 speakers (11 cisgender men, 15 cisgender women, 8 transfeminine speakers), respectively. In general, /s/ and /ʃ/ center of gravity was highest in productions by cisgender women, followed by transfeminine speakers, and then cisgender men speakers. There were no other gender-related differences. Within transfeminine speakers, /s/ and /ʃ/ center of gravity and skewness were not related to the time proportion expressing their feminine spectrum gender or their Trans Women Voice Questionnaire scores. Taken together, the acoustics of /s/ and /ʃ/ may signal gender group identification but may not account for within-gender variation in transfeminine gender expression.

Aeroacoustic differences between the Japanese fricatives [ɕ] and [ç]

To elucidate the linguistic similarity between the alveolo-palatal sibilant [ɕ] and palatal non-sibilant [ç] in Japanese, the aeroacoustic differences between the two consonants were explored via experimentation with participants and analysis using simplified vocal tract models. The real-time magnetic resonance imaging (rtMRI) observations of articulatory movements demonstrated that some speakers use a nearly identical place of articulation for /si/ [ɕi] and /hi/ [çi]. Simplified vocal tract models were then constructed based on the data captured by static MRI, and the model-generated synthetic sounds were compared with speaker data producing [ɕ] and [ç]. Speaker data demonstrated that the amplitude of the broadband noise of [ç] was weaker than that of [ɕ]; the characteristic peak amplitude at approximately 4 kHz was greater in [ç] than in [ɕ], although the mid-sagittal vocal tract profiles were nearly identical for three of ten subjects in the rtMRI observation. These acoustic differences were reproduced by the proposed models, with differences in the width of the coronal plane constriction and the flow rate. The results suggest the need to include constriction width and flow rate as parameters for articulatory phonetic descriptions of speech sounds.

Finite element generation of sibilants /s/ and /z/ using random distributions of Kirchhoff vortices

The numerical simulation of sibilant sounds in three-dimensional realistic vocal tracts constitutes a challenging problem because it involves a wide range of turbulent flow scales. Rotating eddies generate acoustic waves whose wavelengths are inversely proportional to the flow local Mach number. If that is low, very fine meshes are required to capture the flow dynamics. In standard hybrid computational aeroacoustics (CAA), where the incompressible Navier-Stokes equations are first solved to get a source term that is secondly input into an acoustic wave equation, this implies resorting to supercomputer facilities. As a consequence, only very short time intervals of the sibilant can be produced, which may be enough for its spectral characterization but insufficient to synthesize, for instance, an audio file from it or a syllable sound. In this work, we propose to substitute the aeroacoustic source term obtained from the computational fluid dynamics (CFD) in the first step of hybrid CAA, by a random distribution of Kirchhoff's spinning vortices, located in the region between the upper incisors and the lower lip. In this way, one only needs to solve a linear wave equation to generate a sibilant, and therefore avoids the costly large-scale computations. We show that our proposal can recover the outcomes of hybrid CAA simulations in average, and that it can be applied to generate sibilants /s/ and /z/. Modeling and implementation details of the Kirchhoff vortex distribution in a stabilized finite element code are discussed in the paper, as well as the outcomes of the simulations.

A simplified vocal tract model for articulation of [s]: The effect of tongue tip elevation on [s]

Fricative consonants are known to be pronounced by controlling turbulent flow inside a vocal tract. In this study, a simplified vocal tract model was proposed to investigate the characteristics of flow and sound during production of the fricative [s] in a word context. By controlling the inlet flow rate and tongue speed, the acoustic characteristics of [s] were reproduced by the model. The measurements with a microphone and a hot-wire anemometer showed that the flow velocity at the teeth gap and far-field sound pressure started oscillating before the tongue reached the /s/ position, and continued during tongue descent. This behaviour was not affected by the changes of the tongue speed. These results indicate that there is a time shift between source generation and tongue movement. This time shift can be a physical constraint in the articulation of words which include /s/. With the proposed model, we could investigate the effects of tongue speed on the flow and sound generation in a parametric way. The proposed methodology is applicable for other phonemes to further explore the aeroacoustics of phonation.

Aeroacoustic analysis on individual characteristics in sibilant fricative production

The cause of individual acoustic characteristics of sibilant fricatives /s/ and /ʃ/ was analyzed by extracting vocal tract geometries and conducting aeroacoustic experiments and simulations on each geometry. The vocal tract geometries of five Japanese subjects while sustaining /s/ and /ʃ/ were collected by magnetic resonance imaging. Flow and sound generation in the vocal tracts was predicted by large eddy simulations of compressible flow. The characteristic dimensions of the vocal tracts were extracted and simplified vocal tract models were constructed to clarify the relationship between the geometries and the acoustic characteristics. The acoustic characteristics of sounds generated by the simplified models agreed well with the sounds predicted by the simulation, indicating that the proposed model is able to express the individual characteristics in the production of sibilant fricatives. A comparison of the models showed that the volume and length of a space downstream from the constriction are key factors controlling the acoustic characteristics of each subject.

Association of incisal overlaps with /s/ sound and mandibular speech movement characteristics

INTRODUCTION

Modern anterior restorations are intended to achieve esthetic and functional reconstruction and coordination. The positioning of the anterior teeth can affect pronunciation, but the effect of anatomic factors on pronunciation after anterior restoration has not been critically tested. The purpose of this study was to provide possible references for the design of the anterior overlaps in future anterior restorations.

METHODS

Thirty-nine subjects with normal occlusion (NO) participated. They completed questionnaires, were examined clinically, and were recorded pronouncing the /s/ sound. Links between overlaps with spectral features of the /s/ sound and mandibular movements during speech were investigated.

RESULTS

When NO subjects pronounced the /s/ sound, the average fricative length was 202.54 ± 44.57 ms; the average noise peak was 4052.89 ± 445.80 Hz, which was in the high-frequency region; the center of gravity was 2452.85 ± 623.50 Hz; and the mean intensity was 40.61 ± 4.99 dB. The mandibular speech movements showed a slightly long and narrow backward and downward oblique path. Overbite positively correlated with the /s/ sound's noise peak frequency and negatively correlated with the maximum closing speed. Overjet negatively correlated with the maximum distance in the sagittal plane.

CONCLUSIONS

This is the first attempt to correlate the spectral features of the /s/ sound and speaking movements with incisal overlaps. The results suggest that significant associations exist and that these associations can offer some references for esthetic anterior restoration.

Clinical Usefulness of the VS Classification System Using Magnifying Endoscopy with Blue Laser Imaging for Early Gastric Cancer

BACKGROUND

Blue laser imaging (BLI) enables the acquisition of more information from tumors' surfaces compared with white light imaging. Few reports confirm the validity of magnifying endoscopy (ME) with BLI (ME-BLI) for early gastric cancer (EGC). We aimed to assess the detailed endoscopic findings from EGCs using ME-BLI.

METHODS

We enrolled 386 consecutive patients with 417 EGCs that were diagnosed using ME-BLI and resected by endoscopic submucosal dissection. Using the VS classification system, three highly experienced endoscopists (HEEs) and three less experienced endoscopists (LEEs) evaluated the demarcation line (DL), microsurface pattern (MSP), and microvascular pattern (MVP) within the endoscopic images of EGCs obtained using ME-BLI, assigning high-confidence (HC) or low-confidence (LC) levels. We investigated the clinicopathological features associated with each confidence level.

RESULTS

The HEEs' evaluations determined the presence of DL in 99%, irregular MSP in 96%, and irregular MVP in 96%, and the LEEs' evaluations determined the presence of DL in 98%, irregular MSP in 95%, and irregular MVP in 95% of the EGCs. When DL was present, HC levels in the Helicobacter pylori- (H. pylori-) eradicated group and noneradicated group were evident in 65% and 89%, a difference that was significant (p < 0.001).

CONCLUSIONS

In the diagnosis of EGC with ME-BLI, the VS classification system with ME-NBI can be applied, but identifying the DL after H. pylori was difficult.