Accuracy of acoustic rhinometry measurements

Objectives: To identify the factors that influence the accuracy of acoustic rhinometry measurements recorded with commercially available equipment. St udy Design: A simple model was used which consisted of a metal pipe and cyl indrical inserts. These inserts comprised various lengths, and aperture dim ensions were comparable to, or smaller than, the nasal valve areas of both adults and children. Methods: Accuracy of the acoustic rhinometry technique was evaluated by comparing the measured and actual cross-sectional areas. The results were discussed in terms of the calculated acoustic transmission , reflection, and attenuation coefficients of the pipe model variations. Re sults: Reducing the inner diameter of the insert increased the degree of me asurement error. As the length of the insert was increased, the measured cr oss-sectional area gradually decreased, approaching the actual area of the experimental passageway. For larger inserts, level of error was not highly dependent on passageway length compared with the narrower inserts. Conclusi on: Our results show that both the cross-sectional area and passageway leng th of the narrow segment are the most significant factors that influence th e accuracy in acoustic rhinometry measurements.