condition of the vocal cords in respiration, whispering, and phonation. (1)
Ordinary breathing; the cords are separated and the windpipe can be seen.
(2) Deep inspiration; the cords are widely separated and a greater extent
of the windpipe is visible. (3) During the whisper the vocal cords are
separated, leaving free vent for air through the glottis; consequently
there is no vibration and no sound produced by the cords. (4) The soft
vocal note, or aspirate, shows that the chink of the glottis is not
completely closed, and especially the rima respiratoria (the space between
the vocal processes of the pyramidal cartilages.) (5) Strong vocal note,
produced in singing notes of the lower register. (6) Strong vocal note,
produced in singing notes of the higher register.]
Musical notes are comprised between 27 and 4000 vibrations per second. The
extent and limit of the voice may be given as between C 65 vibrations per
second and f''' 1417 vibrations per second, but this is most exceptional,
it is seldom above c''' 1044 per second. The compass of a well-developed
singer is about two to two and a half octaves. The normal pitch, usually
called the "diapason normal," is that of a tuning-fork giving 433
vibrations per second. Now what does the laryngoscope teach regarding the
change occurring in the vocal cords during the singing of the two to two
and a half octaves? If the vocal cords are observed by means of the
laryngoscope during phonation, no change is _seen_, owing to the rapidity
of the vibrations, although a scale of an octave may be sung; in the lower
notes, however, the vocal cords are seen not so closely approximated as in
the very high notes. This may account for the difficulty experienced in
singing high notes piano. Sir Felix Semon in a Friday evening lecture at
the Royal Institution showed some remarkable photographs, by Dr. French, of
the larynx of two great singers, a contralto and a high soprano, during
vocalisation, which exhibit changes in the length of the vocal cords and in
the size of the slit between them. Moreover, the photographs show that the
vocal cords at the break from the lower to the upper register exhibit
characteristic changes.
[Illustration: Fig. 11]
[Description: Fig. 11.--Drawings after Dr. French's photographs in Sir
Felix Semon's lecture on the Voice, (1) Appearance of vocal cords of
contralto singer when singing F# to D; it will be observed that the cords
increase in length with the rise of the pitch, presumably the whole cord is
vibrating, including the inner strand of the vocal muscle. At the break
from D to E (3 and 4) the cords suddenly become shorter and thicker;
presumably the inner portion of the vocal muscle (thyro-arytenoid) is
contracting strongly, permitting only the edge of the cord to vibrate. For
the next octave the cords are stretched longer and longer; this may be
explained by the increasing force of contraction of the tensor muscle
stretching the cords and the contained muscle, which is also contracted.]
When we desire to produce a particular vocal sound, a mental perception of
the sound, which is almost instinctive in a person with a musical ear,
awakens by association motor centres in the brain that preside over the
innervation currents necessary for the approximation and minute alterations
in the tensions of the vocal cords requisite for the production of a
particular note. We are not conscious of any kinæsthetic (sense of
movement) guiding sensations from the laryngeal muscles, but we are of the
muscles of the tongue, lips, and jaw in the production of articulate
sounds. It is remarkable that there are hardly any sensory nerve endings in
the vocal cords and muscles of the larynx, consequently it is not
surprising to find that the ear is the guiding sense for correct modulation
of the loudness and pitch of the speaking as well as the singing voice. In
reading music, visual symbols produced by one individual awakens in the
mind of another mental auditory perceptions of sound varying in pitch,
duration, and loudness. Complex neuro-muscular mechanisms preside over
these two functions of the vocal instrument. The instrument is under the
control of the will as regards the production of the notes in loudness and
duration, but not so as regards pitch; for without the untaught instinctive
sense of the mental perception of musical sounds correct intonation cannot
be obtained by any effort of the will. The untaught ability of correct
appreciation of variations in the pitch of notes and the memorising and
producing of the same vocally are termed a musical ear. A gift even to a
number of people of poor intelligence, it may or may not be associated with
the sense of rhythm, which, as we have seen, is dependent upon the mental
perception of successive movements associated with a sound. Both correct
modulation and rhythm are essential for melody. The sense of hearing is the
primary incitation to the voice. This accounts for the fact that children
who have learnt to speak, and suffer in early life with ear disease, lose
the use of their vocal instrument unless they are trained by lip language
and imitation to speak. The remarkable case of Helen Keller, who was born
blind and deaf, and yet learned by the tactile motor sensibility of the
fingers to feel the vibrations of the vocal organ and translate the
perceptions of these vibrations into movements of the lips and tongue
necessary for articulation, is one of the most remarkable facts in
physiological psychology. Her voice, however, was monotonous, and lacked
the modulation in pitch of a musical voice. Music meant little to her but
beat and pulsation. She could not sing and she could not play the piano.
The fact that Beethoven composed some of his grandest symphonies when stone
deaf shows the extraordinary musical faculty he must have preserved to bear
in his mind the grand harmonies that he associated with visual symbols.
Still, it is impossible that Beethoven, had he been deaf in his early
childhood, could ever have developed into the great musical genius that he
became.
[Illustration: Fig. 12]
[Description: Fig. 12.--Diagram showing the position of the larynx in
respect to the resonator and tongue. The position of the vocal cords is
shown, but really they would not be seen unless one half of the shield
cartilage were cut away so as to show the interior of the voice-box. Sound
vibrations are represented issuing from the larynx, and here they become
modified by the resonator; the throat portion of the resonator is shown
continuous with the nasal passages; the mouth portion of the resonator is
not in action, owing to the closure of the jaw and lips. The white spaces
in the bones of the skull are air sinuses. In such a condition of the
resonator, as in humming a tune, the sound waves must issue by the nasal
passages, and therefore they acquire a nasal character.]
III. THE RESONATOR AND ARTICULATOR
_The Resonator_.--The resonator is an irregular-shaped tube with a bend in
the middle; the vertical portion is formed by the larynx and pharynx, the
horizontal by the mouth. The length of the resonator, from the vocal cords
to the lips, is about 6.5 to 7 inches (_vide_ fig. 12). The walls of the
vertical portion are formed by the vertebral column and the muscles of the
pharynx behind, the cartilages of the larynx and the muscles of the pharynx
at the sides, and the thyroid cartilage, the epiglottis, and the root of
the tongue in front; these structures form the walls of the throat and are
all covered with a mucous membrane. This portion of the resonator passage
can be enlarged to a slight degree by traction upon the larynx below
(sterno-thyroid muscle), by looseness of the pharyngeal muscles, and still
more by the forward placement of the tongue; the converse is true as
regards diminution in size. The horizontal portion of the resonator tube
(the mouth) has for its roof the soft palate and the hard palate, the
tongue for its floor, and cheeks, lips, jaw, and teeth for its walls. The
interior dimensions of this portion of the resonator can be greatly
modified by movements of the jaw, the soft palate, and the tongue, while
the shape and form of its orifice is modified by the lips.
There are accessory resonator cavities, and the most important of these is
the nose; its cavity is entirely enclosed in bone and cartilage,
consequently it is immovable; this cavity may or may not be closed to the
sonorous waves by the elevation of the soft palate. When the mouth is
closed, as in the production of the consonant m, e.g. in singing _me_, a
nasal quality is imparted to the voice, and if a mirror be placed under the
nostrils it will be seen by the vapour on it that the sound waves have
issued from the nose; consequently the nasal portion of the resonator has
imparted its characteristic quality to the sound. The air sinuses in the
upper jaws, frontal bones, and sphenoid bones act as accessory resonators;
likewise the bronchi, windpipe, and lungs; but all these are of lesser
importance compared with the principal resonating chamber of the mouth and
throat. If the mouth be closed and a tune be hummed the whole of the
resonating chambers are in action, and the sound being emitted from the
nose the nasal quality is especially marked. But no sound waves are
produced unless the air finds an exit; thus a tune cannot be hummed if both
mouth and nostrils are closed.
From the description that I have given above, it will be observed that the
mouth, controlled by the movements of the jaw, tongue, and lips, is best
adapted for the purpose of articulate speech; and that the throat, which is
less actively movable and contains the vocal cords, must have greater
influence on the sound vibrations without participating in the articulation
of words. While the vocal cords serve the purpose of the reed, the
resonator forms the body of the vocal instrument. Every sound passes
through it; every vowel and consonant in the production of syllables and
words must be formed by it, and the whole character and individual
qualities of the speaking as well as the singing voice depend in great part
upon the manner in which it is used.
The acoustic effect is due to the resonances generated by hollow spaces of
the resonator, and Dr. Aikin, in his work on "The Voice," points out that
we can study the resonances yielded by these hollow spaces by whispering
the vocal sounds; but it is necessary to put the resonator under favourable
conditions for the most efficient production. When a vowel sound is
whispered the glottis is open (_vide_ fig. 10) and the vocal cords are not
thrown into vibration; yet each vowel sound is associated with a distinct
musical note, and we can produce a whole octave by alteration of the
resonator in whispering the vowel sounds. In order to do this efficiently
it is necessary to use the bellows and the resonator to the best advantage;
therefore, after taking a deep inspiration in the manner previously
described, the air is expelled through the open glottis into the resonating
cavity, which (as fig. 13 shows) is placed under different conditions
according to the particular vowel sound whispered. In all cases the mouth
is opened, keeping the front teeth about one inch apart; the tongue should
be in contact with the lower dental arch and lie as flat on the floor of
the mouth as the production of the particular vowel sound will permit. When
this is done, and a vowel sound whispered, a distinctly resonant note can
be heard. Helmholtz and a number of distinguished German physicists and
physiologists have analysed the vowel sounds in the whispering voice and
obtained very different results. If their experiments show nothing else,
they certainly indicate that there are no universally fixed resonances for
any particular vowel sound. Some of the discrepancies may (as Aikin points
out) be due to the conditions of the experiment not being conducted under
the same conditions. Aikin, indeed, asserts that if the directions given
above be fulfilled, there will be variations between full-grown men and
women of one or two tones, and between different men and different women of
one or two semi-tones, and not much more. As he truly affirms, if the tube
is six inches long a variation of three-quarters of an inch could only make
a difference of a whole tone in the resonance, and he implies that the
different results obtained by these different experimenters were due to the
faulty use of the resonator.
In ordinary conversation much faulty pronunciation is overlooked so long as
the words themselves are intelligible, but in singing and public speaking
every misuse of the resonator is magnified and does not pass unnoticed.
Increased loudness of the voice will not improve its carrying power if the
resonator is improperly used; it will often lead to a rise of pitch and the
production of a harsh, shrill tone associated with a sense of strain and
effort. Aikin claims that by studying the whispering voice we can find for
every vowel sound that position of the resonator which gives us the maximum
of resonance. By percussing[A] the resonator in the position for the
production of the various vowel sounds you will observe a distinct
difference in the pitch of the note produced. I will first produce the
vowel sound _oo_ and proceed with the vowel sounds to _i_; you will observe
that the pitch rises an octave; that this is due to the changes in the form
of the resonator is shown when I percuss the resonator in the position of
the different vowel sounds. You will observe that I start the scale of C
with _oo_ on f and proceed through a series of vowel sounds as in
whispering _who_, _owe_, _or_, _on_, _ah_. I rise a fifth from f to c, and
the diagram shows the change in the form of the resonator cavity to be
mainly due to the position of the dorsum of the tongue. Proceeding from
_ah_ to the middle tone of the speaking register, we ascend the scale to
_i_ as in _me_, and the dorsum of the tongue now reaches the roof of the
mouth; but the tongue not only rises, it comes forward, and the front
segment of the resonator is made a little smaller at every step of the
scale while the back segment becomes a little larger. I consider this
diagram of Aikin to be more representative of the changes in the resonator
than the description of Helmholtz, who stated that the form of the
resonator during the production of the vowel sound _u_ and _o_ is that of a
globular flask with a short neck; during the production of _a_ that of a
funnel with the wide extremity directed forward; of _e_ and _i_ that of a
globular flask with a long narrow neck.
[Footnote A: This was done by the lecturer placing his left forefinger on
the outside of the right cheek, then striking it with the tip of the middle
finger of the right hand, just in the same way as he would percuss the
chest.--F.W.M.]
[Illustration: FIG. 13 I & II To face page 47]
[Description: FIG. 13.--Diagram after Aikin.
1. To show position of tongue and lips in the production of the vowel
sounds _a, o, oo_.
2. To show successive positions of the tongue in the production of the
vowel sounds _a, ei, e, i_.]
I have already said that Helmholtz showed that each vowel sound has its
particular overtones, and the quality or "timbre" of the voice depends upon
the proportional strength of these overtones. Helmholtz was able by means
of resonators to find out what were the overtones for each vowel sound when
a particular note was sung. The flame manometer of König (_vide_ fig. 14)
shows that if the same note be sung with different vowels the serrated
flame image in the mirror is different for each vowel, and if a more
complicated form of this instrument be used (such as I show you in a
picture on the screen) the overtones of the vowel sounds can be analysed.
You will observe that this instrument consists of a number of resonators
placed in front of a series of membranes which cover capsules, each capsule
being connected with a jet of gas.
[Illustration: FIG. 14
Four-sided revolving mirror
Images of gas jets
Resonators, with capsules connected with gas jets]
[Description: FIG. 14.--König's flame manometer. The fundamental note C is
sung on a vowel sound in front of the instrument; the lowest resonator is
proper to that note and the air in it is thrown into corresponding periodic
rhythmical vibrations, which are communicated through an intervening
membrane to the gas in the capsule at the back of the resonator; but the
gas is connected with the lighted jet, the flame of which is reflected in
the mirror, the result being that the flame vibrates. When the mirror is
made to revolve by turning the handle the reflected image shows a number of
teeth corresponding to the number of vibrations produced by the note which
was sung. The remaining resonators of the harmonic series with their
capsules and gas-jets respond in the same manner to the overtones proper to
each vowel sound when the fundamental note is sung.]
Each resonator corresponds from below upwards to the harmonics of the
fundamental note c. In order to know if the sound of the voice contains
harmonics and what they are, it is necessary to sing the fundamental note c
on some particular vowel sound; the resonators corresponding to the
particular harmonics of the vowel sound are thus set in action, and a
glance at the revolving mirror shows which particular gas jets vibrate.
Experiments conducted with this instrument show that the vowel _U=oo_ is
composed of the fundamental note very strong and the third harmonic (viz.
g) is fairly pronounced.
_O_ (_on_) contains the fundamental note, the second harmonic (the octave
c') very strong, and the third and fourth harmonics but weak.
The vowel _A_ (_ah_) contains besides the fundamental note, the second
harmonic, weak; the third, strong; and the fourth, weak.
The vowel _E_ (_a_) has relatively a feeble fundamental note, the octave
above, the second harmonic, is weak, and the third weak; whereas the fourth
is very strong, and the fifth weak.
The vowel _I_ (_ee_) has very high harmonics, especially the fifth, which
is strongly marked.
We see from these facts that there is a correspondence between the
existence of the higher harmonics and the diminished length of the
resonator. They are not the same in all individuals; for they depend also
upon the _timbre_ of the voice of the person pronouncing them, or the
special character of the language used, as well as upon the pitch of the
fundamental notes employed.
Helmholtz inferred that if the particular quality of the vowel sounds is
due to the reinforcement of the fundamental tone by particular overtones,
he ought to be able to produce synthetically these vowel sounds by
combining the series of overtones with the fundamental note. This he
actually accomplished by the use of stopped organ pipes which gave sensibly
simple notes.
* * * * *
Having thus shown that the fundamental note is dependent upon the tension
of the vocal cords--the reed portion of the instrument--and the quality,
timbre, or "klang" upon the resonator, I will pass on to the formation of
syllables and words of articulate speech by the combination of vowel sounds
and consonants.
"The articulate sounds called consonants are sounds produced by the
vibrations of certain easily movable portions of the mouth and throat; and
they have a different sound according as they are accompanied by voice or
not" (Hermann).
The emission of sounds from the resonator may be modified by interruption
or constriction in three situations, at each of which added vibrations may
occur, (1) At the lips, the constriction being formed by the two lips, or
by the upper or lower lip with the lower or upper dental arch. (2) Between
the tongue and the palate, the constriction being caused by the opposition
of the tip of the tongue to the anterior portion of the hard palate or the
posterior surface of the dental arch. (3) At the fauces, the constriction
being due to approximation of the root of the tongue and the soft palate.
Consonants can only be produced in conjunction with a vowel sound,
consequently the air is thrown into sonorous waves of a complex character,
in part dependent upon the shape of the resonator for the production of the
vowel, in part dependent upon the vibrations at each of these situations
mentioned above. Consonants may accordingly be classified as they are
formed at the three places of interruption--lips, teeth, and fauces
respectively: (1) labial; (2) dental; (3) guttural.
The sounds formed at each of the places of interruption are divided into--
1. _Explosives_.--At one of the situations mentioned the resonator is
suddenly opened or closed during the expulsion of air--(_a_) without the
aid of voice, p, t, k; (_b_) with the aid of voice, b, d, g. When one of
these consonants begins a syllable, opening of the resonator is necessary,
e.g. pa; when it ends a syllable, closure is necessary, e.g. ap. No sharp
distinction is possible between p and b, t and d, and k and g if they are
whispered.
2. _Aspirates_.--The resonator is constricted at one of the points
mentioned so that the current of air either expired or inspired rushes
through a small slit. Here again we may form two classes: (_a_) without the
aid of the voice, f, s (sharp), ch, guttural; (_b_) with the aid of voice,
v, z, y. The consonants s and l are formed when the passage in front is
closed by elevation of the tongue against the upper dental arch so that the
air can only escape at the sides between the molar teeth: sh is formed by
the expulsion of the current of air through two narrow slits, viz. (1)
between the front of the tongue and the hard palate, the other between the
nearly closed teeth. If a space be left between the tip of the tongue and
the upper teeth two consonant sounds can be produced, one without the aid
of the voice--th (hard) as in that; the other with the aid of voice--th
(soft) as in thunder. Ch is a guttural produced near the front of the
mouth, e.g. in Christ, or near the back as in Bach.
3. _Resonants_.--In the production of the consonant m, and sometimes n, the
nasal resonator comes into play because the soft palate is not raised at
all and the sound waves produced in the larynx find a free passage through
the nose, while the mouth portion of the resonator is completely closed by
the lips. The sounds thus produced are very telling in the singing voice.
4. _Vibratory Sounds_.--There are three situations in which the consonant r
may be formed, but in the English language it is produced by the vibration
of the tip of the tongue in the constricted portion of the cavity of the
mouth, formed by the tongue and the teeth.
The consonants have been grouped by Hermann as follows:--
| |Labials.|Dentals. |Gutturals.|
|1. Explosives-- | | | |
|a. Without the voice|P |T |K |
|b. With the voice |B |D |G |
|2. Aspirates-- | | | |
|a. Without the voice|F |S (hard), L, Sh,|Ch |
| | |Th (hard) | |
|b. With the voice |V |Z, L, Th, Zh |Y in yes |
| | |(soft) | |
|3. Resonants |M |N |N (nasal) |
|4. Vibratory sounds|Labial R|Lingual R |Guttural R|
H is the sound produced in the larynx by the quick rushing of the air
through the widely opened glottis.
Hermann's classification which I have given is especially valuable as
regards the speaking voice, but Aikin classifies the consonants from the
singing point of view, according to the more or less complete closure of
the resonator.
CLASSIFICATION OF CONSONANTS (AIKIN)
Jaw fully open H, L, K, G
" less " T, D, N, R
" nearly closed, lips closed P, B, M
" " " upper lip on lower teeth F, V
" quite closed S, Z, J, N, Ch, Sh
Aikin, moreover, points out that the English language is so full of
closures that it is difficult to keep the resonator open, and that accounts
for one of the principal difficulties in singing it.