discrimination, it can be improved by training and practice.




CHAPTER II

ELECTRICAL REPRODUCTION OF SPEECH


The art of telephony in its present form has for its problem so to
relate two diaphragms and an electrical system that one diaphragm will
respond to all the fundamental and harmonic vibrations beating upon it
and cause the other to vibrate in exact consonance, producing just
such vibrations, which beat upon an ear.

The art does not do all this today; it falls short of it in every
phase. Many of the harmonics are lost in one or another stage of the
process; new harmonics are inserted by the operations of the system
itself and much of the volume originally available fails to reappear.
The art, however, has been able to change commercial and social
affairs in a profound degree.

Conversion from Sound Waves to Vibration of Diaphragm. However
produced, by the voice or otherwise, sounds to be transmitted by
telephone consist of vibrations of the air. These vibrations, upon
reaching a diaphragm, cause it to move. The greatest amplitude of
motion of a diaphragm is, or is wished to be, at its center, and its
edge ordinarily is fixed. The diaphragm thus serves as a translating
device, changing the energy carried by the molecules of the air into