Jianwu Dang, Kiyoshi Honda
Acoustic characteristics of the human paranasal sinuses derived from sound pressure measurement and morphological observation
Abstract:This paper reports on the acoustic characteristics of the human paranasal sinuses as determined from sound pressure measurement and morphological examination. A new method has been developed in order to explore the anti-resonance patterns of an acoustic tract with a complex shape. This method uses a series of sound pressure measurements at two points: one is at the radiating end and the other moves along the acoustic tract. Spectral and spatial information obtained by the method enables us to acquire frequency and topological details of multiple anti-resonators within the tract. By applying this method to the nasal tract, the resonance frequencies of the paranasal sinuses and locations of their openings were obtained for three subjects, and the locations were used to correlate the resonance frequencies with the corresponding sinuses via the subjects' volumetric MRI data. The accuracy of the method is approximately 10% error, as determined by comparing measured values with numerical results obtained from the morphological data. The results from the experiments indicated that each of the three major sinuses, the sphenoidal, maxillary, and frontal sinuses, contributes its own zeros to the transmission characteristics of the nasal tract. Further, the anti-resonance patterns of the sinuses demonstrate strong individual differences and left-right asymmetry. On the basis of the acoustic and morphological data, the paranasal sinuses were modeled by a set of Helmholtz resonators to produce realistic nasal spectra. It was concluded that the paranasal sinuses not only cause spectral complexity but also shape the nasal formants.