“The stethophone,” An electrical stethoscope

AUSCULTATIO is commonly practiced by means of the ordinary stethoscope, a device with which th e physician is able to study sounds produced within the heart, lungs, or other portions of the body and to determine whether such abnormal conditions exist as are evidenced by abnormal sounds. Of particular importance are the characteristics of the normal heart sounds, heart murmurs, breathing sounds and râles.
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It is well known that the intensity of certain of these sounds is not in itself of fundamental significance, that, for example, certain very faint murmurs may represent serious organic lesions; hence it is of pathological importance that these sounds be heard and understood.