The Vochrome is an original design for an electro-mechanical spectrum analyzer. It separates audio frequencies and harmonics into channels corresponding to notes on the tempered scale of music. It was used with the David Tudor and John Cage performances of ?9 Evenings of Theatre and Engineering?, a historic foray into art and technology done in the late ‘60s

The Vochrome used tuned brass reeds (from a reed organ) as narrow band filters to parse the audio signals into digital outputs corresponding to frequencies on  the tempered scale. For more information about this device and the show, see link:

The Vochrome had an accompanying device; a Switching Matrix that allowed channel reassignment through digital logic and switching functions.  This was used by David Tudor in his performance of “Bandoneon” at the 9 Evenings event.  It served to mix things up nicely for Tudor – just the way he liked it.

I built this device while an intern at the Western Electric Engineering Research Center in Princeton, NJ.
Here is a link to the Switching Matrix: