The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts


Tadashia J. Cooper1, Jon R. Marstrander2, Wesley M. Granger1, Jonathan B. Waugh1; 1Clinical and Diagnostic Sciences, University of Alabama at Birmingham, Birmingham, AL; 2Electrical and Computer Engineering, University of Alabama at Birmingham, Birmingham, AL

Background: Several types of stethoscopes were selected for testing to determine how much sound intensity is lost due to factors such as configuration, materials, and chest piece type. The purpose was to provide an objective basis for comparing stethoscope performance and determine if a relationship between price and performance existed, and the difference between bell and diaphragm chest piece transmission. The hypothesis more expensive stethoscopes would have less sound loss was tested. Methods: Twelve models of stethoscopes (3 of each model, 12 with diaphragm and 9 with bell chest pieces) were tested using audio capture equipment (UA-1G interface with Cakewalk software by Roland Corp., Los Angeles, CA). A speaker (sonitor) designed for interfacing with a stethoscope chest piece was used to send a sinusoidal sound sweep 40-4000 Hz through each stethoscope. The earpiece was connected to a microphone mounted in an anatomically correct ear canal model and the apparatus was placed within an anechoic chamber for measurement in a room with low background noise. The difference between sound input/output equaled the amount of sound lost for each stethoscope (greater average area under the curve (AUC) value means less sound loss). Results: Several bell chest piece models were different from each other (p=0.009) as measured by One-Way ANOVA between Means and the Prestige Medical (PM) model S125 was different than all of the other models by having the least sound loss by Tukey-Kramer Multiple-Comparison test. The same analyses also showed a difference in the diaphragm chest piece models (p=0.002) with the PM model S107 having least sound loss value (different from 8 other models). The average AUC for all bell chest piece models was greater than that of the diaphragm models (p < 0.001) for both full frequency range tested and upper range (1500-4000 Hz) using the Pooled t-test. Correlation and linear regression showed no significant relationship between price and sound loss (r = -0.406 for bell and r = 0.246 for diaphragm). Conclusions: The findings from this small sample indicate some models perform better than others based on this type of controlled measurement but a higher price does not insure better performance. Additional analyses may identify certain models as better for specific frequency sub-ranges and specific applications. Sponsored Research - This student research project was partially supported by Prestige Medical, manufacturer of several of the models tested in the study. Partial funding was in the form of supplying product for testing and purchase of some recording software and supplies.