ly correct mode of operation for the vocal
cords, this correct action has never been determined from the anatomy of
the organs. No doubt there is some difference between the muscular
actions of correct tone-production and those of any incorrect operation
of the voice. But the nature of this difference in muscular action has
never been discovered by means of dissections of the larynx, nor by
laryngoscopic observation.

_The Acoustic Principles of Tone-Production_

An outline of the existing state of knowledge regarding the acoustic
principles of tone-production must be drawn mainly from one source. This
is the latest authoritative work on the subject, _The Study of Speech
Curves_, by E. W. Scripture (Washington, 1906). In this work Prof.
Scripture overthrows several of the conclusions of Helmholtz which had
hitherto furnished the basis of all the accepted theories of vocal
acoustics. Considering the eminently scientific character of all Prof.
Scripture's research work, his thorough acquaintance with every detail
of the subject, and the exhaustive attention devoted to this series of
experiments, we are fully justified in accepting his present statements
as conclusively proved.

A first impression received from a careful reading of _The Study of
Speech Curves_ is that the subject is vastly more intricate than had
formerly been believed. Helmholtz's theory of vocal acoustics was fairly
simple: The vocal cords vibrate after the manner of membranous reeds; a
tone thus produced consists of a fundamental and a series of overtones;
vowel and tone quality are determined by the influence of the resonance
cavities, which reinforce certain of the overtones with special
prominence. This theory is discarded by Prof. Scripture. "The overtone
theory of the vowels cannot be correct." In place of this simple theory,
Prof. Scripture reaches conclusions too complicated to be given in
detail here. A brief outline of the subject must suffice for the needs
of the present work.

Prof. Scripture found that the nature of the walls of a resonating
cavity is of more importance than either its size, shape, or opening. A
flesh-lined cavity is capable of reinforcing tones covering a range of
several notes. Further, the vowel sound, and presumably also the tone
quality, are determined more by the action of the vocal cords than by
the adjustment of the resonance cavities. "The glottal lips vibrate
differently for the different vowels." This adjustme