Part 5 (1/2)
Prof. Helmholtz has by means of his Resonance and Electrical apparatus invented aids by which the forms of the vibrations can be perceived as well as the over-tones, and the different degrees of strength of the latter in relation to one another and to the fundamental tone can be exactly measured. In attempting by means of the above-mentioned apparatus to cause the several over-tones to sound more or less strongly with the fundamental tone, and again entirely to veil others, it became possible to Prof. Helmholtz to produce artificially most opposite timbres, as well as all the vowels of speech.
Even when, in the culture of a voice, we have advanced so far that none of the inharmonic but only the harmonic over-tones sound with the fundamental tone, we shall always find that every voice has its own peculiar _Klangfarbe_--i.e., its own characteristic timbre; and it is not possible so to form the tones of a voice that the over-tones sounding with them shall diminish proportionally according to their height. Every voice has one, mostly two, over-tones, which always predominate in every tone, every register, and give the voice its peculiar quality. When, with the first octave, the fifth above it sounds, the voice is full and mellow. A clear, sympathetic, silvery ring is produced by the sounding of the seventh with the octave immediately above it. One of the most beautiful timbres is a result of the prominence of the third with the seventh, etc. This peculiarity appears to be connected with the particular form and structure of the cavity of the mouth. That parts of the cavity of the mouth serve as a sounding-board in the formation of sound, has already been mentioned.[11]
The perfection of a tone at a certain pitch depends, in the resonance of the cavity of the mouth, upon the utterance of some vowel, to which the parts of the mouth are adjusted; and this perfection is considerably affected by even a slight variation in the timbre of the vowel, as it occurs in different dialects of the same language. On the other hand, the peculiar tones of the cavity of the mouth are almost wholly independent of age and s.e.x. The peculiar pitch of the resonance apparatus has also an influence upon the tone. Every one who knows how to play on any instrument knows that some of its tones sound sweeter and are more easily given than others; these are the tones in which the peculiar tone of the instrument and its over-tones sound together. To describe more particularly the natural laws upon which these facts rest would lead us too far away from our present purpose.
THE VOWELS
Every tone in singing usually takes the sound of some vowel.
By the greater or less distinctness of one or another of the over-tones, sounding with the fundamental tone, various timbres of the vowel are produced. But certain vowels in certain parts of the scale can be sung far more easily and sweetly than others. The investigation of this fact has taught us that a tone gains in richness when the tone corresponding to the vowel belongs to the over-tones of the fundamental tone. In the human voice, however, the tones favorable to the several vowels do not admit of being precisely determined.
In different languages and dialects the vowels have different shades, and a scarcely perceptible variation, especially in the clearer vowels, is sufficient to cause the over-tones to be heard more or less distinctly. After I had learned, with the kind a.s.sistance of Professor Helmholtz, by means of his artificial apparatus for the sharpening of the ear, to find out over-tones and to know their peculiarities, I was soon able, without any artificial help, to discover the vowels favorable to them by the fuller sound of certain tones. In the female voice all tones below the c take the character of _o_. At the c, _a_, p.r.o.nounced as in the English word _hall_, sounds the best, and at d? e pa.s.ses in to _a_, as in _man_, and at f into _a_, as in _may_. With the g the _a_ sounds again as in _man_; a b? b c are favorable to all the vowels, while d e? e sound best with _e_. After e every tone takes the coloring of _a_, as in _father_, and sounds well only with this vowel; b? c d sound again better with _e_.
As thus, above e f all the tones take the coloring of _a_ in _father_, so the tones below c take the timbre of _o_, and the most skilful artists are not able to sing all the vowels in these tones with equal clearness and purity. The female voice, therefore, has only a few tones more than an octave, upon which every one of the vowels can be distinctly sung; and again, all these tones do not afford an equally sonorous tone with every vowel.
As unfortunately our Song composers do not always keep this fact in view, as the old Italians did, and since words with the most unfavorable vowels often underlie the notes, it as often becomes necessary to mingle with the unfavorable vowel something of the sound (_Klang_) of the vowel properly belonging to the note; as, for example, in the word ”ring” upon f, to sing the _i_ with a mixture of the sound (_Klang_) of _a_. Artists do this in a way of which they are for the most part unconscious, and which is always un.o.bserved by the hearer. That in every voice there are several tones upon which every vowel sounds well, finds an explanation in an observation of Professor Helmholtz. The ear is attuned to a certain tone, designated as e4 f4. To persons with very susceptible nerves these tones are often insupportable, and we often see dogs, whose sense of hearing is especially acute, run howling away when the above e4 is struck upon a violin, while to other tones they seem wholly insensible. But all the tones which are accompanied by that tone as an over-tone to which the ear is attuned, sound harmonious even with unfavorable vowels.
PARTIAL TONES
But beside the over-tones, which sound with every good, simple sound, there are other _partial tones_, which, like the long-known combination tones, do not usually present themselves to our consciousness. Combination tones were first discovered in 1745 by the organ-builder, _Sorge_. By an act of concentrated attention one hears these tones at the accord of two different tones. They lie always lower than the interval to which they belong, and arise from the meeting of the nodes of vibration of the tones producing the interval. The node of vibration is the name of that place where, after every completed vibration, the sounding body returns to its former position. When, for instance, we give the third c e, we hear the c, lying an octave lower than the third, sounding at the same time as a combination tone. For the tone c a string has two vibrations, while in the same s.p.a.ce of time e has three.
The vibration node of the c will thus, after two vibrations, coincide with the vibration node of the e. By the coincidence of these nodes of vibration is produced the number of vibrations requisite for the c below. Besides these combination tones there are summation tones, discovered by Helmholtz, which arise from the vibrations collectively (_Gesammtzahl_) belonging to the above interval, and are higher than the interval. Both kinds of partial tones have again their faint over-tones.
BEATS (DIE SCHWEBUNGEN)
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 ill.u.s.trations 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,