Stethoscopes: what are we hearing?

This paper develops an objective methodology to test the audio quality of stethoscopes, classifies stethoscopes into five functional categories, and compares the audio performance of each of the five categories. These categories, based on the manufacturer's recommended use, are basic assessment, cardiology, disposable, high-end cardiology, and physical assessment. The classification into categories is based on the intended performance of the stethoscopes as provided by the manufacturers. After developing the procedures and running more than 500 tests, the stethoscope with the least amount of loss over the spectrum was chosen from each of the five categories; the five were then compared to one another. Thirty-nine stethoscopes from 11 manufacturers were used in this study. The objective test methodology allows for side-by-side comparison of stethoscopes from various manufacturers that is independent of the manufacturer's published test results.