The dynamics of a piano performance are measured by measuring the dynamics of each individual note played. This measurement is accomplished by measuring the "near terminal velocity" of the hammer shank associated with each note, the velocity determining the "loudness" of the note. In order to make this velocity measurement without affecting appreciably the "feel" of the piano, a notched shutter is secured to the hammer shank for the particular hammer associated with each note for cooperation with an optical switch (light source and photo cell). When any one note is played, the corresponding hammer shank will move upwardly to cause the hammer to strike the appropriate piano string and in the upward movement, the top of the shutter will intercept the optical switch to generate an initiating signal. This initiating signal starts a count in an electronic counter. As the shank continues to move upwardly, the bottom edge of the notch will generate an end-of-count signal which will terminate the count in the electronic counter. The time increment defined by the count is inversely proportional to the "near terminal velocity" of the hammer.
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