Accuracy of acoustic rhinometry measurements.

OBJECTIVES To identify the factors that influence the accuracy of acoustic rhinometry measurements recorded with commercially available equipment. STUDY DESIGN A simple model was used which consisted of a metal pipe and cylindrical inserts. These inserts comprised various lengths, and aperture dimensions 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. RESULTS Reducing the inner diameter of the insert increased the degree of measurement error. As the length of the insert was increased, the measured cross-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. CONCLUSION Our results show that both the cross-sectional area and passageway length of the narrow segment are the most significant factors that influence the accuracy in acoustic rhinometry measurements.