The ‘Synthetic Tone’ was an electro-mechanical instrument similar but much smaller to the Choralcelo designed by the Brookline, Massachusetts electrical engineer Sewall Cabot (Cabot, Quincy Sewall b: 4 SEP 1901 in New York d: MAR 1957 in New York). The instrument created complex tones by resonating metal bars with a tone-wheel generated electromagnetic charge.
“One object of my present invention is to provide an improved musical instrument of relatively small cost and small dimensions in comparison to those of a pipe-organ, but capable of attaining all the musically useful results of which a pipe-organ is capable. Another object is to provide an instrument that will produce desirable tonal effects not heretofore obtainable from a pipe-organ.”
Sewal Cabot Patent documents
Early Electronic Music Instruments: Time Line 1899-1950.Curtis Roads Computer Music Journal Vol. 20, No. 3 (Autumn, 1996), pp. 20-23 Published by: The MIT Press