Abstract Fricative /s/ is known to be pronounced by jet generation and subsequent impact on walls of the oral cavity. The prediction of acoustic characteristics of /s/ is an ongoing research topic due to the aeroacoustic nature of the sound source. In this study, acoustic characteristics are modeled using the multimodal theory with monopole and dipole sources positioned in the oral tract waveguide. The oral tract geometry of fricative /s/ was simplified by concatenating rectangular channels whose cross-sectional areas and vertical height are derived from medical imaging. To validate the model accuracy, transverse and sagittal directivity patterns (49 cm every 15°) were measured for flow supplied to a realistic oral tract replica. Comparison between measured and modeled spectra showed that the modeling with the dipole source predicted the pressure amplitude within a discrepancy of ±5 dB up to 14 kHz. Modeled acoustic directivity patterns using a dipole source reflected main tendencies observed on measured directivity patterns in both the transverse and sagittal planes. The proposed modeling approach enables a systematic analysis of the high frequency (>5 kHz) acoustic characteristics as a function of geometrical details for speech production due to an aeroacoustic sound source.

中文翻译：

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具有矩形横截面的口腔的摩擦音 /s/ 声学建模

摘要 已知摩擦音 /s/ 是由射流产生和随后对口腔壁的影响而发音的。由于声源的气动声学特性，/s/的声学特性的预测是一个正在进行的研究课题。在这项研究中，声学特性是使用多模态理论建模的，单极和偶极源位于口腔波导中。擦音 /s/ 的口腔几何结构通过串联矩形通道简化，矩形通道的横截面面积和垂直高度来自医学成像。为了验证模型的准确性，测量了提供给真实口腔复制品的流量的横向和矢状方向性模式（每 15° 49 厘米）。测量光谱和建模光谱之间的比较表明，使用偶极子源进行建模预测压力幅度在 ±5 dB 至 14 kHz 的差异内。使用偶极子源模拟的声学方向性模式反映了在横向和矢状面中测量的方向性模式上观察到的主要趋势。所提出的建模方法能够系统地分析高频（> 5 kHz）声学特性，作为由于气动声源产生的语音的几何细节的函数。