A Multiple Electrical Stethoscope for Teaching

For some years, efforts have been made to secure a multiple stethoscope for use in teaching classes of medical students. An instrument for the subdivision of the sounds from a single large chest piece into a number of rubber tubes leading to the usual stethoscope headpieces has been used by some. For successful operation, however, its capacity is limited to six or eight students, and the sounds are very faint. Heart sounds and murmurs have been transmitted electrically and recorded graphically by Einthoven.1Williams,2using an electromagnetic transmitter and two stages of electrical amplification, secured more accurate graphic records of murmurs. Since we began work on this apparatus, three articles have appeared describing the audible dis heart sounds. Squier3amplified the sounds of the group of physicians. Abbott,4using a transmitter exclude all except very low frequencies, amplified sounds and distributed them through a loud speaker.