Simultaneous breath sound and flow measurements during cough.
Goldsmith WT; Reynolds JS; Afshari AA; Frazer DG
Proceedings of the 25th International Conference on Lung Sounds, Chicago, IL, September 20-22, 2000. Lexington, KY: International Lung Sounds Association, 2000 Sep; :1
When measuring breath sounds from the mouth, care must be taken to minimize the amount of interference from external and internal sources. A recording system composed of concatenated tubes was designed to record cough sounds from the mouth with high fidelity. Normally, a flow measuring device, such as a pneumotach, is placed near the subject's mouth to record an accurate measurement. In this case, it was anticipated that close proximity of the pneumotach to the microphone would cause reflections and filtering characteristics which would alter the sound measured at the microphone. For this reason the pneumotach was placed near the distal end of the tubing system. The recording system was coupled to a voltage controlled piston pump capable of generating arbitrary volume waveforms. Noise signals rich in the frequencies of interest were generated to obtain the transfer function of the recording system. An inverse filter was calculated which accounted for flow measurement errors caused by the distal location of the pneumotach. Eighteen control subjects were asked to cough voluntarily into the recording system. The inverse filter was applied to the pneumotach recordings to provide an accurate measurement of flow from the subject's mouth. Sound intensity was plotted versus air flow from the mouth to examine sound intensity during each phase of the cough.
Breathing; Sound; Sound analyzers; Breathing zone; Analytical instruments; Analytical processes
Abstract; Conference/Symposia Proceedings
Proceedings of the 25th International Conference on Lung Sounds, Chicago, IL