Chest
Clinical Investigations: Miscellaneous: Comparative Study: Journal Article: Research Support, Non-U.S. Gov't: Research Support, U.S. Gov't, Non-P.H.S.Measurement of Respiratory Acoustical Signals: Comparison of Sensors
Section snippets
Subjects and Methods
We used seven sensors that are representative of those commonly used for respiration acoustic studies (Table 1). Three of us served as subjects for the recording of lung sounds after giving informed consent. The study protocol was approved by the Purdue University Committee on the use of human subjects. All three participants were healthy male nonsmokers, ranging in age from 24 to 47 years, in height from 166 to 183 cm, and in weight from 62 to 83 kg. None of the subjects had a respiratory
Results
On average, the length of recording was 20.8 s (range, 16.0 to 30.3 s) for each subject and sensor, and contained six inspirations (range, 4 to 9). The average number of spectra within the target flow range was 34 (range, 18 to 57). We computed the background noise spectra from an average of 31 samples (range, 9 to 70).
The slopes of the spectral curves of inspiratory sounds recorded with air-coupled microphones were steeper compared with those recorded with contact sensors (Table 2). A
Discussion
Our observations on inspiratory lung sounds confirm once again their well-known spectral characteristics,10 showing 99 percent of sound intensity below 600 Hz and greatest amplitudes between 100 and 300 Hz. Expiratory sounds at the same airflows were quieter and not necessarily similar to inspiratory sounds. For this comparison of sensors, however, we concentrated on data acquired during inspiration. Unexpectedly we found steeper spectral slopes with air-coupled microphones compared with
ACKNOWLEDGMENTS
We would like to thank Dr. Ignacio Sanchez for his help and participation as a study subject. We gratefuly acknowledge the technical assistance of Mr. Yuns Oh and secretarial help from Mrs. Doris Jensen.
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This study was supported in part by a grant from the Whitaker Foundation and a National Science Foundation Young Investigator Award BCS-9257488 to Dr. Wodicka. Dr. Pasterkamp is supported by the Childrens Hospital of Winnipeg Research Foundation.
This study was presented in part at the 17th International Conference on Lung Sounds, August, 1992, Helsinki, Finland.