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June 18, 1938


Author Affiliations


JAMA. 1938;110(25):2068-2069. doi:10.1001/jama.1938.62790250003008b

The considerable number of variously designed stethoscopes on the market would lead one to judge not only that there is much difference in taste but that there is probably a difference in quality. More than this, it would seem important for one to know something about the variability introduced by an instrument for the examining of acoustics and something about the sounds to which one is listening.

The intensities of the sounds of the heart and the chest1 are very small, not averaging, for the frequencies they possess, more than 10 decibels in their greatest exaggerations. The frequency characteristics of these various sounds are contained in a very narrow band between 60 and 1,000 cycles. In other words, whereas the normal hearing range lies roughly between 64 and 26,000 cycles, for listening to chests and hearts one is required to have good hearing only in the zone 64-1,000. Yet