Modern Mechanix posted an interesting newspaper snippet from the year 1929: This Instrument Will Register Body Reactions of Student Piano Player.

Pianist body reaction instrument

The article reads:

A NEW device has been patented by Dr. Kurt Johnen, Berlin piano pedagogue, which records the motions and bodily reactions of a piano player to determine if the selection is being properly interpreted. A lady is pictured being examined by the device. A pneumatic belt records the change of the circumference of the chest, pneumatic cuffs about the upper arms control the changes of muscle tension, through a hose is recorded the rhythms of respiration and another hose transfers the strength of touch. Dr. Johnen expects this device will aid him in instructing his pupils in interpretation.

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