quoted from Bacon's essay on studies.

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
forced upwards through the windpipe. The lungs are able to expel air
regularly and gently, with no more expense of energy than ordinary
breathing requires. But the lungs can also force air out with
tremendous power--power enough to carry sound over hundreds of yards.
In ordinary repose the outward moving breath produces no sound
whatever, for it meets in its passage no obstruction.

Producing Tone. At the upper end of the windpipe is a triangular
chamber, the front angle of which forms the Adam's apple. In this are
the vocal cords. These cords are two tapes of membrane which can be
brought closely together, and by muscular tension stretched until
passing air causes them to vibrate. They in turn cause the air above
them to vibrate, much as the air in an organ pipe vibrates. Thus tone
is produced.

The air above the vocal cords may fill all the open spaces above the
larynx--the throat, the mouth, the nasal cavity in the head, the
nostrils. This rather large amount of air, vibrat