The Brain and the Voice in Speech and Song Part 2

[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.]

[Ill.u.s.tration: 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 Konig (_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 a.n.a.lysed.

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.

[Ill.u.s.tration: FIG. 14

Four-sided revolving mirror

Images of gas jets

Resonators, with capsules connected with gas jets]

[Description: FIG. 14.--Konig'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 p.r.o.nounced.

_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 p.r.o.nouncing 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 pa.s.s 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 cla.s.sified as they are formed at the three places of interruption--lips, teeth, and fauces respectively: (1) l.a.b.i.al; (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 cla.s.ses: (_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 pa.s.sage 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 s.p.a.ce 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 pa.s.sage 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:--

| |l.a.b.i.als.|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|l.a.b.i.al R|Lingual R |Guttural R|

H is the sound produced in the larynx by the quick rus.h.i.+ng of the air through the widely opened glottis.

Hermann's cla.s.sification which I have given is especially valuable as regards the speaking voice, but Aikin cla.s.sifies the consonants from the singing point of view, according to the more or less complete closure of the resonator.

CLa.s.sIFICATION 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 princ.i.p.al difficulties in singing it.

"The converse of this may be said of Italian, in which most words end in pure vowels which keep the resonator open. In fact, it is this circ.u.mstance 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,' p.r.o.nounced _voche_, 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 a.s.sociated 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-l.a.b.i.al-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 p.r.o.nunciation 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 a.s.sociation of the component syllables, and the difficulty arises primarily from the progressive impairment of this function of a.s.sociation 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 a.s.sociated. 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 a.s.sociated 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 a.s.sociated 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 s.h.i.+p 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 phosph.o.r.etted 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) a.s.sociation.