Pitch And Sympathetic Vibration
It is sympathetic vibration, manifesting itself in some instances in the
chest and in the head cavities, and in other instances almost entirely
within the latter, that gives to voices their peculiar timbre or
tone-quality--their physiognomy. It is by timbre that we distinguish
voices as we distinguish features. With instruments, differences in
quality of tone--differences in timbre--are due to differences of shape;
and
in case of instruments of the same kind, for example, violins, to
slight differences in form or to the grain, age and quality of the wood.
In the same manner, there are minute differences in the structure of the
vocal tract of different people; and it is especially the structural
differences between the resonant cavities of individual singers that
determine differences of timbre or quality. It is easy to distinguish
between tones even of the same pitch that come from a harp, a violin, a
trumpet, a flute or from the human voice. Between two violins of exactly
the same make, played on by the same person, there would be greater
difficulty in discovering differences in the quality of tone, although,
even if made after the same pattern and about the same date, there
probably would be minute structural differences that would differentiate
their timbre to a musical ear; while if, of two violins, one of the
instruments were new, and the other old, a musical ear probably would
immediately detect differences in their tone-quality.
It is easier to distinguish between voices even of the same range,
than between instruments of the same kind, because there is strong
individuality in voices. This is due to the fact that structural
differences between the vocal tracts of individuals are far more
numerous and far more minute than possibly can be introduced into
instruments. Moreover, the vocal tract, being part of the human body,
is subtly responsive to innumerable impulses and adjusts and readjusts
itself in innumerable ways. Instruments are made of material, chiefly
wood and metal, and, unlike the vocal tract, cannot change structurally.
The cornet, for example, is made of brass. The lips of the player
protruding into the cup can effect certain changes in shape, and changes
also can be made in the tube between the mouthpiece and the bell of the
instrument by pistons or valves. But these changes are absurdly small
in number compared with the structural changes of which the vocal tract
is capable, and commonplace in character compared with the refined and
subtle minuteness of the latter. For this reason, while there is a
distinct timbre for each kind of instrument, there are innumerable
timbres of the human voice--as many as there are voices, and all due
to the pliability of the vocal tract.
It is the manner in which the numerous individual conformations of
the vocal tract affect the overtones in the voice that makes voices
different from each other; for the overtones are the chief agency in
determining the timbre, quality, or physiognomy of any tone. Every
tone consists of a fundamental or ground tone with its overtones. The
fundamental tone determines the pitch; the overtones determine the
quality, tone-color, timbre, or physiognomy of the tone.
The overtones, or harmonics, as they also are called, vibrate in certain
simple harmonic relations with the fundamental--from twice to five
times as often per second, sounding the octave above, the fifth of that
octave, the second octave, the major third of that octave, etc. So
important is it to the individual musical quality of tone, to secure the
cooperation of overtones, that in certain large open organ pipes, which
are deficient in these, extra pipes of higher pitch and corresponding
with the overtones of the fundamental note, are added and joined to the
register. Overtones without the fundamental can be obtained on stringed
instruments by stopping one of the strings and then touching it lightly
at other points. The soft, sweet, ethereal character of the harmonics
produced in this manner on a violin conveys some idea of the manner in
which the many overtones of a note give it its distinctive quality.
In a way the overtones may be said to echo the fundamental, but the
ear receives fundamental and overtones blended as one tone of a
certain timbre. What that timbre is, is determined by the shape of
the resonating cavity or cavities, the shape of which in turn is
determined by the shape of the instrument, and in different voices by
infinitesimal differences in the shape of various parts of the vocal
tract. All instruments of a kind are made more or less on the same
pattern and vary but little in shape. For this reason we have the
distinct violin, horn, clarinet or pianoforte timbre, and so on down
the list, but I repeat here that there are not such minute and
individual differences between instruments of the same kind as there
are between voices of the same range, because there are no such
minute and individual structural differences in instruments as in the
vocal organs of individuals--differences that each individual can
multiply ad infinitum by the subtle and delicate play of muscles
acting in response to mental suggestion, art sense, inspiration,
temperament, psychic impulse, or by whatever cognate term one may
choose to call it.
There is little or nothing of psychology in Mackenzie's book, and yet,
like other writers on voice-production, he appears now and then to be
groping for it. Thus, when he speaks of the fundamental tone being
reinforced by its overtones--by a number of secondary sounds higher in
pitch and fainter in intensity--he adds very beautifully that every
resonance-cavity has what may be called its elective affinity, or one
particular note, to the vibrations of which it responds sympathetically
like a lover's heart answering that of his beloved. "As the crude tone
issues from the larynx, the mouth, tongue and soft palate, moulding
themselves by the most delicately adaptive movements into every
conceivable variety of shape, clothe the raw bones of sound with body
and living richness of tone. Each of the various resonance-chambers
reechoes its corresponding tone, so that a single well-delivered note
is, in reality, a full choir of harmonious sounds."
Voice being, like instrumental tone, a commixture of fundamental and
overtones, and the manner in which the composite conformation of
collective waves strikes the ear being largely determined by the
cavities of resonance, the control of these is of great importance to
the singer. This control should, by thorough training, be brought to
such a degree of efficiency that it becomes subconscious and automatic,
so that the resonance-cavities shape themselves instantly to the note
that is being produced within the larynx and, vibrating in sympathy with
it, sound the overtones. The reciprocal principle of elective affinity
between fundamental and overtone, between the shape assumed by the
larynx for pitch and the shape assumed by the resonance-cavities for
quality, is illustrated by the exciting influence of a sounding
instrument upon a silent one tuned to the same pitch which, although not
touched by human hand, sounds in sympathy with the one that is being
played on. Even a jar standing upon a mantel-shelf, a globe on a lamp,
a glass on a table, or some other object in the room, may vibrate and
rattle when a certain note is struck on the pianoforte. This is the
result of sympathetic vibration. Thus, although vocal tone originates
within the larynx, it sets the resonance-cavities into sympathetic
vibration, and these produce the harmonics that give the fundamental
tone its timbre; the resonance-cavities being to the vocal cords or
lips what the body or resonance-box of the violin and the sounding-board
of the pianoforte are to their strings, the tube of a cornet or horn to
the lips, the body of the clarinet to its reed--the resonating factor
which determines the overtones and through these the timbre.
Excepting the chest and trachea the resonance-cavities of the voice are
located above the larynx. To the chest as a resonator the low tones of
the voice owe much of their great volume. Indeed, the chest is such a
superb and powerful resonating box that, if it resonated also for
the high tones, these, with their inherent capacity for penetration,
probably would become disagreeably acute. Therefore, nature, wise in
this as in many other things, has decreased chest vibration as the voice
ascends the scale.
Above the larynx is the pharynx, a space extending to the base of the
skull and opening into the mouth, and higher up connecting with the base
of the nose by means of two passages, the posterior nares, or back nasal
passages. The walls of the pharynx are permeated by a network of muscles,
so that this important space or resonance-cavity immediately above the
larynx is susceptible of numerous adjustments and readjustments in size
and shape; and as it lies with its back wall against the spinal column,
it also is susceptible and immediately responsive to suggestion from
the mind.
Another important resonance-cavity, indeed, the most important, is the
mouth, roofed by the hard palate which separates the mouth from the
nasal chamber, to which latter it also forms the floor. In the mouth is
the tongue, extremely mobile, and thus capable of materially changing
the size and shape of the mouth-cavity. Hanging from the rear of the
hard palate, like a veil over the root of the tongue, is the soft
palate; attached to which is the uvula. This hangs vertically down from
the soft palate and, if the rear end of the tongue is allowed to bulge
upward slightly, can be made to form with it a kind of valve, by which
voice is conveyed directly into the mouth-cavity without any of it
escaping up the posterior nasal passage; while the soft palate by itself
alone can be drawn up so as to touch the back wall of the pharynx,
completely closing the passage to the nose, so that a continuous curved
resonance-cavity is afforded from larynx to lips.
The soft palate is continued on either side by two folds known as the
fauces; and each of the fauces has two ridges, the pillars of the
fauces, between which are the tonsils. The pillars of the fauces enclose
muscular fibres which act respectively on the tongue, the sides of the
pharynx, and the upper part of the larynx, and thus aid in the necessary
movements of the vocal tract.
The nasal passage, divided into two ducts by a vertical partition, the
vomer septum, was referred to in the chapter on inspiration. The
so-called sinuses are hollow spaces in small bones on either side and
above the nasal passage and communicating directly or indirectly with
it. A question regarding the nasal cavity, including the sinuses,
suggests itself. Of what use is the nasal passage as a cavity of
resonance if, in order to prevent a nasal quality of tone, the passage
during voice-emission is shut off by the action of the soft palate, or
by the combined action of the soft palate, uvula and tongue? The answer
is, first, that it is not always to be closed off, because there are
times when a slightly nasal timbre in voice is desirable; secondly,
that even when the nasal cavity is shut off, the hard palate being
not only the roof of the mouth but also the floor of the nose, its
vibrations are communicated to the nasal cavity, but not directly enough
to give a disagreeable nasal quality to the voice.
From this survey it will be seen that the cavities of resonance along
the vocal tract may be divided into such parts as are solid, pliable
and movable. The solid parts are sharply resonant; they are, par
excellence, the resonators in voice-production; while a pliable part,
like the pharynx, although resonant in a less degree, is valuable in
adjusting structural shape to every condition that arises; and the most
movable parts of all, the tongue and the lips, probably wholly devoid
of resonance, have their great roles to play in effecting what may be
called wholesale changes in the size and shape of the mouth-cavity,
which could not be brought about by any other agencies less mobile.
The roof of the mouth, the teeth, the hard gums, the cones of the nasal
passage, and the sinuses are the solid portions of the cavities of
resonance. When Svengali gazed into Trilby's mouth and exclaimed,
"Himmel, what a roof!" he spoke from the depths of vocal knowledge.
For a highly arched mouth roof, especially if the tone enters the mouth
cavity from a wide, well-rounded pharynx, is of great value to the
singer. So is a fine, shapely, regular set of teeth, especially as
regards the upper front teeth, behind which the vibrations appear to
centre in so called "forward production." Cautiously brought into play,
the posterior nasal passage assists, with its resonance, the head tones
of the female voice and the upper range of male voices; but care must
be taken not to carry the tone up into the nose and thus give it a nasal
quality.
Some writers class the walls of the pharynx with the solid parts of the
vocal tract. But the walls of the pharynx are pliable, as already has
been pointed out, together with the admirable results to be derived from
their flexibility when under the singer's control. The movable parts of
or pertaining to the resonance-cavities are the soft palate with the
uvula, the fauces, the cheeks, the lips, the lower jaw and, most mobile
of all, the tongue.
The uvula often is too long, either by nature or through a disease
called prolongation of the uvula. It can be treated by astringents or
the elongation can be cut off, which usually is the most prompt and
efficacious way. The operator, however, in case the patient is a singer,
must calculate to a nicety just how much to remove, otherwise the voice
will suffer. There are isolated cases of deformed soft palate with uvula
so enormous that it cannot be raised. In such cases, one of which is
instanced by Kofler, a surgical operation being out of the question, the
patient simply has to give up singing.
Enlarged tonsils, whether from inflammation or other causes, also
have to be operated on, as their enlargement obviously hinders free
voice-emission. Even at its best the mouth-passage here is narrowest--and
called the "isthmus"--and nothing must be allowed to make it narrower
than it is by nature. The lips never should lie flat against the teeth,
since this would muffle resonance. On the other hand, the teeth should
not be bared, as this results in a foolish grin. The cheeks naturally
conform to the action of the lips. The lower jaw should be relaxed, which
gives the so-called "floating chin." When the lower jaw, and with it
the chin, is raised, the throat is tightened, and voice-action becomes
constricted. The "floating chin" does not, of course, mean that the chin
is to be thrust downward into the chest. In singing, as in everything
else, there is a golden rule to be observed.
It is obvious that the tongue also is a highly responsible member of
the vocal tract. Raise it too high, and you bring it so close to the
hard palate that the mouth becomes too small for free, resonant
voice-emission. The tone becomes wheezy. Let the tongue lie too flat,
and the mouth-cavity becomes too large and cavernous for tense, vibrant
voice-emission. The tone becomes too open. Let the base of the tongue
move back too far, and it will tend to close the pharynx and to check
free egress from the pharynx into the mouth, making the tone muffled.
Raise the back of the tongue until it touches the soft palate, and the
two combined close the mouth-cavity from behind, with the result that
voice is carried up the nasal passage and is charged with a disagreeable
nasal quality.
For every tone produced there is a special adjustment throughout the
entire vocal tract. These adjustments should, by practice, become
automatic, simple acts of swift and unconscious obedience to the will.
Then the question of "forward," "backward," or "middle" production,
according to the part of the roof of the mouth where the tone-vibrations
appear to centre, will become a matter wholly of the quality of voice
which it is desired to produce for any given emotional state. Forward
production--vibration appearing to centre a little back of the upper
front teeth--is, as a general thing, the best. Yet a voice brilliant to
the point of hardness can be mellowed by middle or backward production.
These are matters of judgment. But when I am told, as I was by a young
girl, that she was being taught to centre the tone-vibrations "back of
her eyes," all I can do is to throw up my hands and exclaim, "O
voice-production, what crimes are committed in thy name!" Yes--there
should be a Rescue League, or a Society for the Prevention of Cruelty
to Singers.