The vibrations of telephone diaphragms

History Investigations of the vibrations of telephone diaphragms have been published by Rayleigh,¹ Wien,² Kempf-Hartmann,³ Taylor⁴, Gati⁵ and others. Rayleigh and Wien measured the value of the simple harmonic current which would just produce an audible tone in the receiver at different frequencies. They found that at certain frequencies the current required was a minimum, and Wien concluded that these minima showed the existence of natural vibrations of the diaphragm, but realized that the variation in sensibility of the ear with pitch played possibly a larger part in the difference of current required at different frequencies than the natural vibrations themselves.