Novel techniques, standardization tools to enhance reliability of acousticrhinometry measurements

Acoustic rhinometry measurements are influenced by factors related to subje ct posture, breathing, inclination and positioning of the wavetube, leaks a nd distortion at the nostril - nose adapter connection and ambient noise. W e present simple techniques to control these errors. Thus, gel on contoured nose adapters, shadow tracing to maintain posture, laser homing for wavetu be alignment, are all integrated into a practical scheme that is easy to im plement and causes minimum discomfort to subjects. Repeatability improved t o Below 3% coefficient of variation (CV) in non decongested subjects when t rained operators used all the techniques together viz. gel on nose adaptors , shadow tracing, laser homing. In a factorial experiment, repeated measure ments were made on subjects over two consecutive days with operator trainin g and standardization tools as variables. An analysis of variance identifie d the most important factors to be gel on contoured nose adapters, operator training and control of breathing. With gel, the mean CV between readings was 5.8%, measurement time 30.3 seconds. The tools, especially gel and shad ow tracing, helped untrained operators achieve performance levels that were more comparable with trained operators. Reproducible curves could be taken rapidly. Thus a significant difference of 31.2 seconds between untrained a nd trained operators reduced to 12.6 seconds using tools. These techniques significantly improve the reliability, speed and ease of doing repeated aco ustic rhinometry measurements and thus the quality of data generated in nas al studies.