ACOUSTIC CHARACTERISTICS OF THE HUMAN PARANASAL SINUSES DERIVED FROM TRANSMISSION CHARACTERISTIC MEASUREMENT AND MORPHOLOGICAL OBSERVATION

This paper reports on the acoustic characteristics of the paranasal si nuses as determined from transmission characteristic measurements and morphological examinations. A new experimental approach was developed to explore the correspondence between antiresonance frequencies and th e causal resonators [J. Dang and K. Honda, J. Acoust. Sec. Jpn. (E) 17 , 93-99 (1996)], and it was adopted to determine the antiresonance fre quency of each sinus cavity. In this study, the antiresonance frequenc ies and the locations of the sinus openings were estimated from transm ission characteristics of the nasal tract for three subjects, and then MRI-based morphological data for the subjects were used to relate eac h antiresonance frequency to its causal sinus cavity. The results indi cate that each of the three major sinuses, i.e., the sphenoidal, maxil lary, and frontal sinuses, contributes its own antiresonances to the t ransmission characteristics of the nasal tract. The estimated antireso nance frequencies were compared with computed natural frequencies of H elmholtz resonators, and the differences were within 10% for the sinus es. On the basis of the frequency distribution of the sinus antiresona nce, the acoustic characteristics of the paranasal sinuses were modele d by four Helmholtz resonators. The simulation with the four-zero mode l showed that the paranasal sinuses not only introduce antiresonances in the transfer function, but also change the spectral shape of the na sal formants. (C) 1996 Acoustical Society of America.