CHAPTER II

THE VOICE


Organs of Speech. Although the effects produced by the human voice are
myriad in their complexity, the apparatus involved in making the
sounds which constitute speech is extremely simple. In construction it
has been usually compared to an organ pipe, a comparison justifiable
for imparting a non-technical understanding of its operation.

An organ pipe is a tube in which a current of air passing over the
edge of a piece of metal causes it to vibrate, thus putting into
motion the column of air in the pipe which then produces a note. The
operating air is forced across the sounding piece of metal from a
bellows. The tube in which the thin sounding plate and the column of
air vibrate acts as a resonator. The resulting sound depends upon
various sizes of the producing parts. If the tube is quite long the
sound is low in pitch. If the tube is short the sound is high.
Stopping the end of the pipe or leaving it open alters the pitch. A
stopped pipe gives a note an octave lower than an open pipe of the
same length. The amount of the vibrating plate which is allowed to
move also determines the pitch of a note. If the air is under great
pressure the note is loud. If the air is under little pressure the
note is soft.

It is quite easy to transfer this explanation to the voice-producing
apparatus in the human body.

To the bellows correspond the lungs from which the expelled air is