rower end to the thyroid cartilage, and possessing a midrib overhanging and corresponding to the fissure of the glottis. The broader end of the leaf points freely upwards toward the tongue, in which direction the entire cartilage presents a concave, as towards the larynx a convex, outline. In swallowing, the epiglottis falls over the larynx, like a saddle on the back of a horse. In the formation of certain letters a horizontal narrow fissure may be produced by depressing the epiglottis over the vertical false and true vocal chords. Within the larynx (4, 5), rather above its middle, between the thyroid and arytenoid cartilages, are two elastic ligaments, like the parchment of a drum split in the middle, and forming an aperture which is called the interior or true glottis, and corresponds in direction with the exterior glottis. This aperture is provided with muscles, which enlarge and contract Fig. 5. it at pleasure, and otherwise modify the form of the larynx. The three cartilages of the larynx supply the most perfect mechanism for stretching or relaxing the chords, and likewise, as it would seem, for deadening some portion of them by pressure of a protuberance on the under side of the epiglottis (in German, Epiglottiswulst). These chords are of different length in children and grown-up people, in man and in woman. Their average length in man is 18 mm. when relaxed, 23 mm. when stretched; in woman, 12 mm. when relaxed, 15 mm. when stretched: thus giving a difference of about one third between the two sexes, which accounts for the different pitch of male and female voices.1 The tongue, the cavity of the fauces, the lips, teeth, and palate, with its velum pendulum and uvula performing the office of a valve between the throat and nostrils, as well as the cavity of the nostrils themselves, are all concerned in modifying the impulse given to the breath as it issues from the larynx, and in producing the various vowels and consonants. After thus taking to pieces the instrument, the tubes and reeds as it were of the human voice, let us now see how that instrument is played by us in speaking or in singing. Familiar and simple as singing or music in general seems to be, it is, if we analyze it, one of the most wonderful phenomena. What we hear when listening to a chorus or a symphony is a commotion of elastic air, of which the wildest sea would give a very inadequate image. The lowest tone which the ear perceives is due to about 30 vibrations in one second, the highest to about 4000. Consider, then, what happens in a Presto when thousands of voices and instruments are simultaneously producing waves of air, each wave crossing the other, not only like the surface waves of the water, but like spherical bodies, and, as it would seem, without any perceptible disturbance;2 consider that each tone is accompanied by secondary tones, that each instrument has its peculiar timbre, due to secondary vibrations; and, lastly, let us remember that all this cross-fire of waves, all this 1 Funke, Lehrbuch der Physiologie, p. 664, from observations made by J. Müller. 2 Weber, Wellenlehre, p. 495. - whirlpool of sound, is moderated by laws which determine what we call harmony, and by certain traditions or habits which determine what we call melody, both these elements being absent in the songs of birds, that all this must be reflected like a microscopic photograph on the two small organs of hearing, and there excite not only perception, but perception followed by a new feeling even more mysterious, which we call either pleasure or pain; and it will be clear that we are surrounded on all sides by miracles transcending all we are accustomed to call miraculous, and yet disclosing to the genius of an Euler or a Newton laws which admit of the most minute mathematical determination. For our own immediate purposes it is important to remark that, while it is impossible to sing without at the same time pronouncing a vowel, it is perfectly possible to pronounce a vowel without singing it. Why this is so we shall see at once. If we pronounce a vowel, what happens? Breath is emitted from the lungs, and some kind of tube is formed by the mouth through which, as through a clarinet, the breath has to pass before it reaches the outer air. If, while the breath passes the chorda vocales, these elastic lamina are made to vibrate periodically, the number of their vibrations determines the pitch of our voice, but it has nothing to do with its timbre or Vowel. What we call vowels are neither more nor less than the qualities, or colors, or timbres of our voice, and these are determined by the form of the vibrations, which form again is determined by the form of the buccal tubes. This had, to a certain extent, been anticipated by Professor Wheatstone in his critique1 on Professor Willis's ingenious experiments, but it has now been rendered quite evident by the researches of Professor Helmholtz. It is, of course, impossible to watch the form of these vibrations by means of a vibration microscope, but it is possible to analyze them by means of resounding tubes, like those before described, and thus to discover in them what, as we saw, is homologous with the form of vibration, viz. the presence and absence of certain harmonics. If a man sings the same note on different vowels, the harmonics which answer to our resounding tubes vary as they would vary if the same note was played on the violin, or flute, or some other musical instruments. In order to remove all uncertainty, Professor Helmholtz simply inverted the experiment. He took a number of tuning-forks, each furnished with a resonance box, by advancing or withdrawing which he could give their primary tones alone various degrees of strength, and extinguish their secondary tones altogether. He tuned them so as to produce a series of tones answering to the harmonics of the deepest tuning-fork. He then made these tuning-forks vibrate simultaneously by means of a galvanic battery; and by combining the harmonics, which he had first discovered in each vowel by means of the sounding tubes, he succeeded in reproducing artificially exactly the same vowels.2 They We know now what vowels are made of. They. are produced by the form of the vibrations. vary like the timbre of different instruments, and we in reality change the instruments on which we speak when we change the buccal tubes in order to pro 1 London and Westminster Review, Oct. 1837, pp. 34, 37. |