pure vowels which keep the resonator open. In fact, it is this circumstance
which has made the Italian language the basis of every point of voice
culture and the producer of so many wonderful singers." As an example
compare the English word 'voice,' which begins with closure and ends with
closure, and the Italian 'voce,' pronounced _voché_, with its two open
vowel sounds. The vowel sound ah on the note c is the middle tone of the
speaking register, and as we know, can be used all day long without
fatigue; therefore in training the voice the endeavour should be made to
develop the register above and below this middle tone. In speaking there is
always a tendency under emotional excitement, especially if associated with
anger, to raise the pitch of the voice, whereas the tender emotions lead
rather to a lowering of the pitch. Interrogation generally leads to a rise
of the pitch; thus, as Helmholtz pointed out, in the following sentence
there is a decided fall in the pitch--"I have been for a walk"; whereas in
"Have you been for a walk?" there is a decided rise of pitch. If you utter
the sentence "Who are you?" there is a very definite rise of pitch on
'are.'
PATHOLOGICAL DEGENERATIVE CHANGES PRODUCING SPEECH DEFECTS
AND WHAT THEY TEACH
As I have before remarked, children utter vowel sounds before consonants,
and I used this as an argument that phonation preceded articulation; but
there is another reason for supposing that articulate sounds are of later
development phylogenetically, as well as ontogenetically. Not only are they
more dependent for their proper production on intelligence, but in those
disorders of speech which occur as a result of degenerative processes of
the central nervous system the difficulty of articulate speech precedes
that of phonation. Take, for example, bulbar paralysis, a form of
progressive muscular atrophy, a disease due to a progressive decay and
destruction of the motor nerve cells presiding over the movements of the
tongue, lips, and larynx, hence often called glosso-labial-laryngeal palsy.
In this disease the lips, tongue, throat, and often the larynx are
paralysed on both sides. "The symptoms are, so to speak, grouped about the
tongue as a centre, and it is in this organ that the earliest symptoms are
usually manifested." (Gowers). Imperfect articulation of those sounds in
which the tongue is chiefly concerned, viz. the lingual consonants l, r, n,
and t, causing indistinctness of speech, is the first symptom; the lips
then become affected and there is difficulty in the pronunciation of sounds
in which the lips are concerned, viz. u, o, p, b, and m. Eventually
articulate speech becomes impossible, and the only expression remaining to
the patient is laryngeal phonation, slightly modulated and broken into the
rhythm of formless syllables.
The laryngeal palsy _rarely_ becomes complete. The nervous structures in
the _physiological mechanism_ of speech and phonation are affected in this
disease; but there are degenerative diseases of the brain in which the
_psychical mechanism_ of speech is affected, e.g. General Paralysis of the
Insane, in which the affection of speech and hand-writing is quite
characteristic. There is at first a hesitancy which may only be perceptible
to practised ears, but in which there is no real fault of articulation once
it is started; sometimes preparatory to and during the utterance there is a
tremulous motion about the muscles of the mouth. The hesitation increases,
and instead of a steady flow of modulated, articulate sounds, speech is
broken up into a succession of irregular, jerky, syllabic fragments,
without modulation, and often accompanied by a tremulous vibration of the
voice. Syllables are unconsciously dropped out, blurred, or run into one
another, or imperfectly uttered; especially is difficulty found with
consonants, particularly explosive sounds, b, p, m; again, linguals and
dentals are difficult to utter. Similar defects occur in written as in
vocal speech; the syllables and even the letters are disjointed; there is a
fine tremor in the writing, and inco-ordination in the movements of the
pen. Silent thoughts leave out syllables and words in the framing of
sentences; consequently they are not expressed by the hand. The ideation of
a written or spoken word is based upon the association of the component
syllables, and the difficulty arises primarily from the progressive
impairment of this function of association upon which spoken and written
language so largely depends. Examination of the brain in this disease
explains the cause of the speech trouble and the progressive dementia (loss
of mind) and paralysis with which it is associated. There is a wasting of
the cerebral hemispheres, especially of the frontal lobes, a portion of the
brain which, later on, we shall see is intimately associated with the
function of articulate speech.
THE CEREBRAL MECHANISM OF SPEECH AND SONG
Neither vocalisation nor articulation are essentially human. Many of the
lower animals, e.g. parrots, possess the power of articulate speech, and
birds can be taught to pipe tunes. The essential difference between the
articulate speech of the parrot and the human being is that the parrot
merely imitates sounds, it does not employ these articulate sounds to
express judgments; likewise there are imbecile human beings who,
parrot-like, repeat phrases which are meaningless. Articulate speech, even
when employed by a primitive savage, always expresses a judgment. Even in
the simple psychic process of recalling the name aroused by the sight of a
common object in daily use, and in affixing the verbal sign to that object,
a judgment is expressed. But that judgment is based upon innumerable
experiences primarily acquired through our special senses, whereby we have
obtained a knowledge of the properties and uses of the object. This
statement implies that the whole brain is consciously and unconsciously in
action. There is, however, a concentration of psychic action in those
portions of the brain which are essential for articulate speech;
consequently the word, as it is mentally heard, mentally seen, and mentally
felt (by the movements of the jaw, tongue, lips, and soft palate), occupies
the field of clear consciousness; but the concept is also the nucleus of an
immense constellation of subconscious psychic processes with which it has
been associated by experiences in the past. In language, articulate sounds
are generally employed as objective signs attached to objects with which
they have no natural tie.
In considering the relation of the Brain to the Voice we have not only a
physiological but a psychological problem to deal with. Since language is
essentially a human attribute, we can only study the relation of the Brain
to Speech by observations on human beings who during life have suffered
from various speech defects, and then correlate these defects with the
anatomical changes found in the brain after death.
Between the vocal instrument of the primitive savage and that of the most
cultured singer or orator there is little or no discoverable difference;
neither by careful naked-eye inspection of the brain, nor aided by the
highest powers of the microscope, should we be able to discover any
sufficient structural difference to account for the great difference in the
powers of performance of the vocal instrument of the one as compared with
that of the other; nor is there any sufficient difference in size or minute
structure of the brain to account for the vast store of intellectual
experiences and knowledge of the one as compared with the other. The
cultured being descended from cultured beings inherits tendencies whereby
particular modes of motion or vibration which have been experienced by
ancestors are more readily aroused in the central nervous system; when
similar stimuli producing similar modes of motion affect the sense organs.
But suppose there were an island inhabited only by deaf mutes, upon which a
ship was wrecked, and the sole survivors of the wreck were infants who had
never used the voice except for crying, would these infants acquire
articulate speech and musical vocalisation? I should answer, No. They would
only be able to imitate the deaf mutes in their gesture language and
possibly the musical sounds of birds; for the language a child learns is
that which it hears; they might however develop a simple natural language
to express their emotions by vocal sounds. The child of English-speaking
parents would not be able spontaneously to utter English words if born in a
foreign country and left soon after birth amongst people who could not
speak a word of English, although it would possess a potential facility to
speak the language of its ancestors and race.
It is necessary, however, before proceeding further, to say a few words
explanatory of the brain and its structure, and the reader is referred to
figs. 15, 16, 17. The brain consists of (1) the great brain or cerebrum,
(2) the small brain or cerebellum, and (3) the stem of the brain, which is
continuous with the spinal cord. The cerebro-spinal axis consists of grey
matter and white matter. The grey matter covers the surface of the cerebrum
and cerebellum, the white matter being internal. The stem of the brain, the
medulla oblongata, and the spinal cord, consists externally of white
matter, the grey matter being internal. The grey matter consists for the
most part of nerve cells (ganglion cells), and the white matter consists of
nerve fibres; it is white on account of the phosphoretted fatty
sheath--myelin--that covers the essential axial conducting portion of the
nerve fibres. If, however, the nervous system be examined microscopically
by suitable staining methods, it will be found that the grey and white
matters are inseparably connected, for the axial fibres of the nerves in
the white matter are really prolongations of the ganglion cells of the grey
matter; in fact the nervous system consists of countless myriads of nervous
units or neurones; and although there are structural differences in the
nervous units or neurones, they are all constructed on the same general
architectural plan (_vide_ fig. 15). They may be divided into groups,
systems, and communities; but there are structural differences of the
separate systems, groups, and communities which may be correlated with
differences of function. The systems may be divided into: (1) afferent
sensory, including the special senses and general sensibility; (2) motor
efferent; (3) association.
[Illustration: Fig. 15]
[Description: FIG. 15.--Diagrammatic representation of a motor neurone
magnified 300 diameters. Whereas the nerve cell and its branching processes
(the dendrons) form but a minute speck of protoplasm, the nerve fibre which
arises from it, although microscopic in diameter, extends a very long
distance; in some cases it is a yard long; consequently only a minute
fraction of the nerve fibre is represented in the diagram.]
The great brain or cerebrum consists of two halves equal in weight, termed
hemispheres, right and left; and the grey matter covering their surface is
thrown into folds with fissures between, thus increasing enormously the
superficial area of the grey matter and of the neurones of which it
consists without increasing the size of the head. The pattern of the folds
or convolutions shows a general similarity in all human beings, certain
fissures being always present; and around these fissures which are
constantly present are situated fibre systems and communities of neurones
having particular functions (_vide_ fig. 16.) Thus there is a significance
in the convolutional pattern of the brain. But just as there are no two
faces alike, so there are no two brains alike in their pattern; and just as
it is rare to find the two halves of the face quite symmetrical, so the two
halves of the brain are seldom exactly alike in their pattern. Although
each hemisphere is especially related to the opposite half of the body, the
two are unified in function by a great bridge of nerve fibres, called the
corpus callosum, which unites them. The cortical centres or structures with
specialised functions localised in particular regions of one hemisphere are
associated by fibres passing to the same region in the opposite hemisphere
by this bridge.
[Illustration: Fig. 16]
[Description: FIG. 16.--Diagram of the left hemisphere of the brain showing
localised centres, of which the functions are known. It will be observed
that the centres for the special senses, tactile, muscular, hearing, and
vision, are all situated behind the central fissure. The tactile-motor
kinæsthetic sense occupies the whole of the post-central convolution; the
centre for hearing (and in the left hemisphere memory of words) is shown at
the end of the first temporal convolution, but the portion shaded by no
means indicates the whole of the grey cortex which possesses this function;
a large portion of this centre cannot be seen because it lies within the
fissure forming the upper surface of the temporal lobe. Behind this is the
angular gyrus which is connected with visual word memory. The half-vision
centre, and by this is meant the portion of brain which receives
impressions from each half of the field of vision, is situated for the most
part on the inner (unseen) surface of the occipital lobe. In front of the
central fissure is situated the motor area, or that region destruction of
which causes paralysis of the muscles moving the structures of the opposite
half of the body. If the situations indicated by black dots be excited by
an interrupted electric current, movements of the limbs, trunk, and face
occur in the precise order shown, from the great toe to the larynx. In
front of this precentral convolution are the three frontal convolutions,
and it would seem that the functions of these convolutions are higher
movements and attention in fixation of the eyes; moreover, in the lowest
frontal region, indicated by fine dots, we have Broca's convolution, which
is associated with motor speech; above at the base of the second middle
frontal convolution is the portion of cortex in which is localised the
function of writing. Taste and smell functions reside in brain cortex only
a small portion of which can be seen, viz. that at the tip of the temporal
lobe.]
Muscles and groups of muscles on the two sides of the body which invariably
act together may thus be innervated from either hemisphere, e.g. the
muscles of the larynx, the trunk, and upper part of the face.
Gall, the founder of the doctrine of Phrenology, wrecked his fame as a
scientist by associating mental faculties with conditions of the skull
instead of conditions of the brain beneath; nevertheless, he deserves the
highest credit for his discoveries and deductions, for he was the first to
point out that that part of the brain with which psychic processes are
connected must be the cerebral hemispheres. He said, if we compare man with
animals we find that the sensory functions of animals are much finer and
more highly developed than in man; in man, on the other hand, we find
intelligence much more highly developed than in animals. Upon comparing the
corresponding anatomical conditions, we see, he said, that in animals the
deeper situated parts of the brain are relatively more developed and the
hemispheres less developed than in man; in man, the hemispheres so surpass
in development those of animals that we can find no analogy. Gall therefore
argued that we must consider the cerebral hemispheres to be the seat of the
higher functions of the mind. We must moreover acknowledge that the
following deductions of Gall are quite sound: "The convolutions ought to be
recognised as the parts where the instincts, feelings, thoughts, talents,
the affective qualities in general, and the moral and intellectual forces
are exercised." The Paris Academy of Science appointed a commission of
inquiry, May, 1808, which declared the doctrine of Gall to be erroneous.
Gall moreover surmised that the faculty of language lay in the frontal
lobes, and Bouillaud supported Gall's proposition by citing cases in which
speech had been affected during life, and in which after death the frontal
lobes were found to be damaged by disease. A great controversy ensued in
France; popular imagination was stirred up especially in the republic by
the doctrine of Gall, which was an attempt to materialise and localise
psychic processes. Unfortunately Gall's imagination, encouraged by a
widespread wave of popular sympathy, overstepped his judgment and launched
him into speculative hypotheses unsupported by facts. His doctrine of
Phrenology was shown to be absolutely illogical; consequently it was
forgotten that he was the pioneer of cerebral localisation.
SPEECH AND RIGHT-HANDEDNESS
The next step in Cerebral Localisation was made by a French physician, Marc
Dax, who first observed that disease of the left half of the cerebrum
producing paralysis of the right half of the body (right hemiplegia) was
associated with loss of articulate speech. This observation led to the
establishment of a most important fact in connection with speech, viz. that
right-handed people use their left cerebral hemisphere as the executive
portion of the brain in speech. Subsequently it was shown that when
left-handed people were paralysed on the left side by disease of the right
hemisphere, they lost their powers of speech. But the great majority of
people are born right-handed, consequently the right hand being especially
the instrument of the mind in the majority of people, the left hemisphere
is the leading hemisphere; and since probably specialisation of function of
the right hand (dexterity) has been so closely associated with that other
instrument of the mind, the vocal instrument of articulate speech, the two
have now become inseparable; for are not graphic signs and verbal signs
intimately interwoven in the development of language and human
intelligence?
What has determined the predominance of the left hemisphere in speech? I
can find no adequate anatomical explanation. There is no difference in
weight of the two hemispheres in normal brains. Moreover, I am unable to
subscribe to the opinion that there is any evidence to show that the left
hemisphere receives a larger supply of blood than the right. Another theory
advanced to explain localisation of speech and right-handedness in the left
hemisphere is that the heavier organs, lung and liver, being on the right
side have determined a mechanical advantage which has led to
right-handedness in the great majority of people. This theory has, however,
been disposed of by the fact that cases in which there has been a complete
transposition of the viscera have not been left-handed in a larger
proportion of cases. The great majority of people, modern and ancient,
civilised and uncivilised, use the right hand by preference. Even graphic
representations on the sun-baked clay records of Assyria, and the drawings
on rocks, tusks, and horns of animals of the flint-weapon men of
prehistoric times show that man was then right-handed. There is a
difference of opinion whether anthropoid apes use the right hand in
preference to the left. Professor Cunningham, who made a special study of
this subject, asserts that they use either hand indifferently; so also does
the infant at first, and the idiot in a considerable number of cases. Then
why should man, even primitive, have chosen the right hand as the
instrument of the mind? Seeing that there is no apparent anatomical reason,
we may ask ourselves the question: Is it the result of an acquired useful
habit to which anatomical conditions may subsequently have contributed as a
co-efficient? Primitive man depended largely upon gesture language, and the
placing of the hand over the heart is universally understood to signify
love and fidelity. Uneducated deaf mutes, whose only means of communicating
with their fellow-men is by gestures, not only use this sign, but imply
hatred also by holding the hand over the heart accompanied by the sign of
negation. Moreover, pointing to the heart accompanied by a cry of pain or
joy would indicate respectively death of an enemy or friend. Again,
primitive man protected himself from the weapons of his enemies by holding
the shield in his left hand, thus covering the heart and leaving the right
hand free to wield his spear. The question whether it would have been to
his advantage to use either hand indifferently for spear and shield has
been, to my mind, solved by the fact that in the long procession of ages
evolution has determined right-handed specialisation as being more
advantageous to the progress of mankind than ambidexterity.
Right-handedness is an inherited character in the same sense as the
potential power of speech.
LOCALISATION OF SPEECH CENTRES IN THE BRAIN
In 1863 Broca showed the importance in all right-handed people (that is in
about ninety-five per cent of all human beings) of the third _left_ frontal
convolution for speech (_vide_ figs. 16 and 17); when this is destroyed by
disease, although the patient can understand what is said and can
understand written and printed language, the power of articulate speech is
lost. _Motor Aphasia_. This portion of the brain is concerned with the
revival of the motor images, and has been termed by Dr. Bastian "the
glosso-kinæsthetic centre," or the cortical grey matter, in which the
images of the sense of movement of the lips and tongue are formed (_vide_
fig. 17). A destruction of a similar portion of the cortex in a
right-handed person produces no loss of speech; but if the person is
left-handed there is aphasia, because he, being left-handed, uses the third
_right_ inferior frontal convolution for speech. These facts have for long
been accepted by most neurologists, but recently doubts have been cast upon
this fundamental principle of cerebral localisation by a most distinguished
French neurologist, M. Marie; he has pointed out that a destructive lesion
of the cortex may be accompanied by subcortical damage, which interrupts
fibres coming from other parts of the brain connected with speech.
In the study of speech defects it is useful to employ a diagram; a certain
part of the brain corresponds to the _Speech Zone_ there indicated, and
lesions injuring any part of this area in the left hemisphere cause speech
defects (_vide_ fig. 17). All neurologists, M. Marie included, admit this,
and the whole question therefore is: Is a destruction of certain limited
regions of the superficial grey matter the cause of different forms of
speech defects, or are they not due more to the destruction of subcortical
systems of fibres, which lie beneath this cortical speech zone?
There is a certain portion of the speech zone which is assumed to be
connected with the revival of written or printed language, and is called
the _visual word-centre_. There is another region connected with the memory
of spoken words--the _auditory word-centre_; you will observe that it is
situated in the posterior third of the first temporal convolution, but this
does not comprise nearly the whole of it, for there is an extensive surface
of grey matter lying unseen within the fissure, called the transverse
convolutions, or gyri. Lesions of either of these regions give rise to
_Sensory Aphasia_, which means a loss of speech due to inability to revive
in memory the articulate sounds which serve as verbal symbols, or the
graphic signs which serve as visual symbols for language.
[Illustration: FIG. 17]
[Description: FIG. 17.--Diagram to illustrate the Speech Zone of the left
hemisphere (Bastian). This scheme is used to explain the mechanism of
speech, but probably the centres are not precisely limited, as shown in the
diagram; it serves, however, to explain disorders of speech. Destruction of
the brain substance in front of the central fissure gives rise to what is
termed Motor Aphasia and Motor Agraphia, because the patient no longer
recalls the images of the movements necessary for expressing himself in
articulate speech or by writing. Destructive lesions behind the central
fissure may damage the portion of the brain connected with the mental
perception of the sounds of articulate language, or the portion of the
brain connected with the mental perception of language in the form of
printed or written words--Sensory Aphasia; the former entails inability to
speak, the latter inability to read.