We have explained the movements of the waves of sound by the
movements on the surface of water, and we know that, instead of
the billows and hollows that we have in the water, the air is
condensed and rarefied. We know further that if two different
lines of waves run along with one another, their crests and
hollows fall together, and their crests become as high again and
their hollows as deep again. So two tones from different sources
of sound are twice as strong when they are both equally high,
and a new tone of the same height added to them will still
further increase the sound. But when two agitations of the
surface of the water so move that the crests of one fall into
the hollows of the other, their movements neutralize each other.
The same thing happens in tones when one is not struck until
half the vibrations of the preceding tone are concluded. But if
the sounding bodies vary in only a small part of a vibration
sound, they will be alternately stronger and weaker, and this is
termed beats (_Schwebungen_), which are only produced by tones
_very near to each other_. Those intervals whose combination and
over-tones so fall together that many beats are produced, sound
harsh and disagreeable, and we call them dissonances.
Those intervals in which few or no beats occur are called
consonances. As the combination or interfering tones, as well
as the beats, have importance and interest only in harmonizing
several voices, in tuning pianos, as well as in composition in
general, and as we have in view in these pages only the culture
of single voices, we cannot further enlarge on these discoveries,
interesting as they are. According to the purpose of this little
work, I introduce only so much of the latest investigations and
discoveries as will help to show the prevailing evils of our mode
of teaching singing, and, by their practical application to the
business of instruction, serve to improve the vocal art. But
whoever has an interest in this branch of science will find in the
invaluable work of Helmholtz, “Die Lehre von den Tonempfindungen,”
an abundance of most interesting observations and of the most
thoroughly scientific illustrations of the theory of music, and
of those processes in the domain of tone which we have hitherto
always felt, but never understood.
APPLICATION OF THE NATURAL LAWS LYING AT THE FOUNDATION OF
MUSICAL SOUNDS TO THE CULTURE OF THE VOICE IN SINGING
The parts of the human voice that generate tones are the membranous
vocal ligaments or chords, which are subject to the same natural laws
as all sounding bodies; of this we may satisfy ourselves by observing
the different registers of the voice by means of the laryngoscope. The
lower, stronger tones of both series of the chest register show the
ligaments in full vibration, and becoming more strongly stretched with
every higher tone. In the second series the glottis appears, by the
inaction of the arytenoid cartilages, to be shortened. In the falsetto
register the vibrating body is diminished, as only the edges vibrate,
while the same processes are repeated as in the chest register by the
greater stretching of the ligaments and the shortening of the glottis.
The head register, likewise, shows the glottis partly closed, and the
vibrating ligaments gradually stretched more and more.
The vocal ligaments are made to vibrate by the air coming from
the lungs through the trachea, to which they present resistance.
These vibrations are communicated to the air in the mouth and
outside, and are felt by the ear as sound.
As the strength of the tone depends upon the amplitude of the
waves of sound, they, in their turn, depend upon the structure
of the organ of singing, and of the parts of the mouth serving
as a sounding-board or resonant apparatus, but, above all, upon
the skilful management of the vibrating air. And although a fine
timbre of the tones and due skill in increasing the amplitude of
the vibrations may cause the voice to appear fuller and stronger,
yet it is not in our power, when once the vocal organs have been
fully developed, to make a strong voice out of a weak one.
Always to strike the true pitch fully and clearly requires
persevering attention, as well from the teacher as from the
pupil. And long practice is often required before the intonations
become as pure as is indispensably necessary to good singing. For
only upon the basis of a full, pure tone is a beautiful timbre
(_Klangfarbe_) possible.
But the most important thing in the culture of the voice is
the timbre of the tones, for _here it is in our power to form
out of a sharp, hard and disagreeable voice, a voice sweet
and pleasing_.
We have seen that the timbre is dependent on the forms of the
vibrating waves, and the different degrees of strength and number
of the over-tones arising from these forms. It has been further
shown that the simple round form of the waves of vibration produces
the softest, fullest timbre. By this form the fundamental tone is
the strongest, and the over-tones are heard ascending to the third
octave with decreasing degrees of strength. Such a tone is natural
to certain voices. In most cases it must be more or less acquired.
A good tone in singing is formed,
1. By controlling and correctly dividing the air or breath
as it is expired;
2. By a correct direction of the vibrating column of air;
this is done by the right touch (_Tonansatz_);
And, 3. By a very distinct, quick and elastic _touch_.