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Background: Earlier studies have shown that nasalization affects the radiated spectrum by modifying the vocal tract transfer function in a complex manner. Methods: Here we study this phenomenon by measuring sine-sweep response of 3-D models of the vowels /u, a, ᴂ, i/, derived from volumetric MR imaging, coupled by means of tubes of different lengths and diameters to a 3-D model of a nasal tract. Results: The coupling introduced a dip into the vocal tract transfer function. The dip frequency was close to the main resonance of the nasal tract, a result in agreement with the Fujimura & Lindqvist in vivo sweep tone measurements [Fujimura & Lindqvist, 1972]. With increasing size of the coupling tube the depth of the dip increased and the first formant peak either changed in frequency or was split by the dip. Only marginal effects were observed of the paranasal sinuses. For certain coupling tube sizes, the spectrum balance was changed, boosting the formant peaks in the 2 – 4 kHz range. Conclusion: A velopharyngeal opening introduces a dip in the transfer function at the main resonance of the nasal tract. Its depth increases with the area of the opening and its frequency rises in some vowels., QC 20220216

Background: Nasal and paranasal cavities are supposed to contribute substantially to the vocal tract resonator properties. However, their acoustical effects as well as the effects of sinus surgery on the voice remain unclear. In this work we investigate resonance phenomena of paranasal sinuses prior to and after various rhinosurgical procedures in cadaveric human sinonasal tracts and corresponding 3D casts. Methodology: Nasal and paranasal cavities of formalin-preserved cadavers and corresponding 3D replicas were excited by sine tone sweeps from an earphone placed in the epipharynx.The response was picked up by a microphone at the nostrils. Different FESS procedures were performed and the acoustical responses following excitation were recorded.The measured acoustical changes in the obtained transfer functions were then evaluated. Results: Marked low frequency dips were detected in the transfer functions when sinus cavities were included in the nasal resonator system. These dips showed a significant correlation with sinus volumes. Following FESS procedures they moved upwards in frequency depending on the extent of the surgical intervention. Conclusions: The transfer functions obtained in cadaveric situs and 3D replicas showed dips at the resonance frequencies of the paranasal cavities. Marked acoustic effects in terms of increase in dip frequency following FESS procedures were reproducibly documented., QC 20170530

The significance of nasal resonance and anti-resonance to voice production is a classical issue in vocal pedagogy and voice research. The complex structure of the nasal tract produces a complex frequency response. This complexity must be heavily influenced by the morphology of the paranasal cavities, but their contributions are far from being entirely understood. Detailed analyses of these cavities are difficult because of their limited accessibility. Here we test different methods aiming at documenting the acoustical properties of the paranasal tract. The first set of experiments was performed under in vivo conditions, where the middle meatus was occluded by means of targeted application of a maltodextrin mass under endoscopic control. The efficiency of this occlusion method was verified by measuring the nasal nitric oxide (NO) output during humming. In another experiment the frequency responses to sine sweep excitation of an epoxy mould of a nasal cavity were measured, with and without elimination of paranasal sinuses. The third experiment was conducted in a cadaveric situs, with and without maltodextrin occlusion of the middle meatus and the sphenoidal ostia. The results show that some nasal tract resonances were unaffected by the manipulation of the paranasal cavities. Providing access to a maxillary sinus resulted in marked dips in the response curve while access to the sphenoidal ostium caused only minor effects., QC 20160308

Background: The contribution of the nasal and paranasal cavities to vocal tract resonator properties is unclear as are voice effects of sinus surgery. Here we investigate resonance phenomena of paranasal sinuses with and without selective occlusion of the middle meatus and maxillary ostium in a cadaver. Methodology: Nasal and paranasal cavities of a Thiel-embalmed cadaver were excited by sine-tone sweeps from an earphone in the epipharynx.The response was picked up by a microphone at the nostrils. Different conditions with blocked and unblocked middle meatus were tested. Additionally, infundibulotomy was performed allowing direct access to and selective occlusion of the maxillary ostium. Results: Responses showed high reproducibility. Minor effects appeared after removal of meatal occlusion. A marked low frequency dip was detected after removal of occlusion of maxillary ostium following infundibulotomy. Conclusion: Reproducible frequency responses of nasal tract can be derived from cadaver measurements. Marked acoustic effects of the maxillary sinus appeared only after direct exposure of the maxillary ostium following infundibulotomy., QC 20140704

Background: The contribution of the nasal and paranasal cavities to the vocal tract resonator properties is unclear. Here we investigate these resonance phenomena of the sinonasal tract in isolation in a cadaver and compare the results with those gained in a simplified brass tube model. Methods: The resonance characteristics were measured as the response to sine sweep excitation from an earphone. In the brass model the earphone was placed at the closed end and in the cadaver in the epipharynx. The response was picked up by a microphone placed at the open end of the model and at the nostrils, respectively. A shunting cavity with varied volumes was connected to the model and the effects on the response curve were determined. In the cadaver, different conditions with blocked and unblocked middle meatus and sphenoidal ostium were tested. Additionally, infundibulotomy was performed allowing direct access to and selective occlusion of the maxillary ostium. Results: In both the brass model and the cadaver, a baseline condition with no cavities included produced response curves with clear resonance peaks separated by valleys. Marked dips occurred when shunting cavities were attached to the model. The frequencies of these dips decreased with increasing shunting volume. In the cadaver, a marked dip was observed after removing the unilateral occlusion of the middle meatus and the sphenoidal ostium. Another marked dip was detected at low frequency after removal of the occlusion of the maxillary ostium following infundibulotomy. Conclusion: Combining measurements on a simplified nasal model with measurements in a cadaveric sinonasal tract seems a promising method for shedding light on the acoustic properties of the nasal resonator., QC 20150417