Realistic 3D avian vocal tract model demonstrates how shape affects sound filtering (Passer domesticus)

Despite the complex geometry of songbird’s vocal system, it was typically modelled as a tube or with simple mathematical parameters to investigate sound filtering. Here, we developed an adjustable computational acoustic model of a sparrow’s upper vocal tract (Passer domesticus), derived from micro-CT scans. We discovered that a 20% tracheal shortening or a 20° beak gape increase caused the vocal tract harmonic resonance to shift towards higher pitch (11.7% or 8.8%, respectively), predominantly in the mid-range frequencies (3-6 kHz). The oropharyngeal-esophageal cavity (OEC), known for its role in sound filtering, was modelled as an adjustable 3D cylinder. For a constant OEC volume, an elongated cylinder induced a higher frequency shift than a wide cylinder (70% versus 37%). We found that the OEC volume adjustments can modify the OEC first harmonic resonance at low frequencies (1.5–3 kHz) and the OEC third harmonic resonance at higher frequencies (6-8 kHz). This work demonstrates the nee..., The dimensions of the trachea, larynx, beak, tongue, and other anatomical features derive from CT scan images of a whole-body specimen of a house sparrow, preserved in 70% ethanol and stained with iodine-potassium iodine dissolved in water for four weeks (Morphosource: usnm:birds:657964 Passer domesticus – ark:/87602/m4/M115379). The device used to acquire these images was a General Electric phoenix v|tome|x m, Smithsonian Institution Bio-Imaging Research (SIBIR) Center (National Museum of Natural History, Smithsonian Institution), with a X, Y, and Z pixel spacing of 0.067805 mm. The contrast agent used to prepare the specimen allows for the visualisation of soft tissues (tongue, cheeks, etc.) and provides accurate modelling of the entire 3D vocal system shape, in place. This specimen was used to investigate the chemical effects of staining (Early et al., 2020), therefore it corresponds to a well-preserved specimen, prepared in optimal condition for CT-scan acquisition. Bone demineraliz..., You need COMSOL Multiphysics® (COMSOL, 2021) software to open the models.

尽管鸣禽发声系统的几何结构极为复杂，过往研究通常将其简化为管状结构，或采用简单数学参数进行建模，以探究声音滤波特性。本研究基于显微CT扫描数据，构建了家麻雀（Passer domesticus）上声道的可调谐计算声学模型。我们发现，气管缩短20%或喙张开角度增加20°时，发声管的谐波共振会向更高频段偏移（分别为11.7%和8.8%），该效应主要集中在3~6 kHz的中频段。
口咽食管腔（oropharyngeal-esophageal cavity, OEC）在声音滤波中发挥关键作用，本研究将其建模为可调节的三维圆柱体。在口咽食管腔体积保持恒定的前提下，细长型圆柱体相较于宽型圆柱体，可引发更高的频率偏移（分别为70%和37%）。我们还发现，调整口咽食管腔体积，能够改变其在1.5~3 kHz低频段的一次谐波共振，以及6~8 kHz高频段的三次谐波共振。本研究证实了……
本研究中气管、喉、喙、舌及其他解剖结构的尺寸，均来自于家麻雀（Passer domesticus）全身标本的CT扫描图像。该标本经70%乙醇固定，并用碘-碘化钾水溶液染色四周（Morphosource编号：usnm:birds:657964 Passer domesticus – ark:/87602/m4/M115379）。扫描使用的设备为通用电气（General Electric）phoenix v|tome|x m型扫描仪，由史密森尼学会生物成像研究中心（Smithsonian Institution Bio-Imaging Research, SIBIR，隶属于史密森尼国家自然历史博物馆）完成扫描，其X、Y、Z轴像素间距为0.067805 mm。本次使用的造影剂可清晰显示舌、颊部等软组织，并能精准原位重建完整三维发声系统的形态。该标本此前已被用于探究染色的化学效应（Early et al., 2020），因此属于保存状态良好、适配CT扫描采集的最优制备标本。骨骼脱矿……
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