1. R. Bruce Lindsay, Historical introduction to the reprinting of Rayleigh’s Theory of Sound, Dover, New York, NY, 1945, p. xxix.
2. F.V. Hunt, Electroacoustics, Harvard University Press, Cambridge, MA, 1954. Reprinted by the Acoustical Society of America, Woodbury, NY, 1982, p. 65.
3. F.V. Hunt, Electroacoustics.
4. In 1911, in his cork-walled room on the Boulevard Haussman, Marcel Proust was able to listen to performances of the Paris Opera over a special telephone, called the theatrophone. (George D. Painter), Marcel Proust, 2nd ed., Random House, New York, NY, 1989, vol. 2, p. 168.)
5. F.V. Hunt, Electroacoustics, pp. 40–41.