Before the EKG: Making the Electricity in Nerves and Muscles Audible — 1919

Man wired to a device of vacuum tubes, transformer and speaker, 1927. This followed up on an experiment by Rudolf Höber in 1919 to make audible variations in electrical current in human cells. Physiological Institute, University of Kiel, Germany.

I love this picture.  A balding man in a brown work coat lies on a wooden garden lounge chair incongruously brought into the paneled rooms of the Physiological Institute at the University of Kiel, Germany in 1927.  The experimental subject is wired to an electrical apparatus on a table that is in turn wired to a morning-glory-shaped loudspeaker horn.  We are standing with a group of medical students waiting intently for the sound of the subject’s heart muscles and nerves to emerge from the horn (and perhaps hoping that the 100-volt battery that powers the apparatus doesn’t do him any harm).  The device emitted rhythmic notes of varying tones and intensity as the electrical impulses in the muscles and nerves varied with the heartbeat.  Sometimes called the “electric stethoscope,” this instrument was adapted as a teaching tool to train doctors to diagnose the condition of the heart through sound.

Rudolf Höber, Professor of Physiology, University of Kiel.

One of the first persons to use the amplified sound of the heart to teach use of the stethoscope was my grandfather, Rudolf Höber (1873-1953).  He was a pioneering physiologist at the Universities of Zürich, Kiel and Pennsylvania who has been remembered for discoveries in biochemistry and biophysics at the cellular level. A couple of years ago, The Journal of Electrical Bioimpedence noted the 100th anniversary of Rudolf’s discoveries related to the variability of electrical charges across cell membranes.  Among other things, Rudolf was an inventor who devised instruments for measuring electrical characteristics at the cellular level; he even had a glass blower working for him to fabricate apparatus.  Here is his diagram of a bioelectric device he created around 1910:

Ronald Pethig’s labeling of Rudolf’s diagram for his bioelectric measurement device, 2012.

During World War I, the technology of vacuum tubes was developed that enabled the amplification of electrical waves for use in telephones.  Rudolf adapted this technology to use in combination with his earlier bioelectric measurement devices — resulting in the mechanism at the top of this page.

Early vacuum tubes similar to those used by Rudolf Höber to amplify the electrical impulses generated in nerve and muscle cells.

This year the University of Kiel is marking its 350th anniversary with a series of events, including the medical school’s exhibition on prominent scientists who worked there.  You can get information about the overall exhibition by clicking here and about Rudolf in particular here.

The street adjacent to the Physiological Institute at the University of Kiel is named for my grandfather. Photograph by my friend Nancy Greenspan.