Elsewhere1 I have reported in a short preliminary note on the voice in chorea as analyzed by the aid of the vocal kymograph. This was merely the first blush, the original snap-shot of a single isolated case.
That note briefly reviewed the literature since 1841, showed the vagueness of former descriptions of choreic vocal changes, the antiquated methods of vocal analysis, the advantages of modern methods, and finally presented — as far as I know — the first clear statement of just what choreic voice is. Without reiterating at length the details of that preliminary note, let me briefly state that the voice-change as reported on the kymograph consists in a variation in two vocal elements — a rise in pitch and an increase in intensity. This vocal change was so constant and so uniformly simultaneous with other choreiform movements that I there presented the claim that these vocal
SWIFT WB. FURTHER ANALYSIS OF THE VOICE SIGN IN CHOREA. Am J Dis Child. 1914;VIII(4):279-282. doi:10.1001/archpedi.1914.04300010287003