66 larynx serve principally to produce those modifications of the voice the larynx (omitting the cornua and the epiglottis) as seen after dissection, from above. The muscles are here designated by numbers, the cartilages by letters, viz. 1. The crico-thyroideus (at the rima of the glottis). 2. The thyreo-arytenoideus. 3. The crico-arytenoideus posticus. 4. The crico-arytenoideus lateralis. 5. Half of the arytenoideus transversus and of the obliqui. A. The thyreoid cartilage. B. The cricoid. C. The arytenoids. F. The vocal or inferior laryngeal ligaments. H. The ligaments which tie the arytenoids to the cricoid. * Elem. Physiol. vol. i, p. 1023. + Ibid. p. 1003. Cambridge Philos. Trans. 1832. Larynx. Tabular view. 453. Mr. Willis's tabular view of the action of the muscles of the larynx is as follows: Antagonists. Antagonists. Close the glottis. aperture of the glottis. Sound. When perceptible. part of the arytenoids (4). Arytænoidei transversales and obliqui, compress Mr. Mayo thinks, "that for vocalization, the ligaments may acquire a definite tension, joined with contact for their whole length; and that to allow the air to pass without producing a laryngeal sound, the same tension being at the same time maintained, the ligaments may require to be drawn apart, and the rima glottidis to be opened at its posterior part." 454. The reed instrument (as Müller calls it), which is formed by this curious adaptation of parts, produces sound, according to those laws of acoustic science which have been so fully and clearly explained in Sir John Herschel's able work on that subject. In using the word "sound," however, I must observe a difference between certain words in other languages with which it is sometimes confounded. For instance, the French word son has, according to Chladni, three dif ferent significations: it expresses i. All that we perceive by the sense of hearing. ii. What we perceive by appreciable vibrations of the air. These three significations, says he, answer respectively to the three German words schall, klang, and ton.* The English word sound, however, includes at most only the two first of these meanings. It is derived from the Latin sonus, which is defined to be "quicquid auribus percipi potest." Now this perception is occasioned, as Diomedes says, by a "corporalis collisio;" and every such collision causes certain vibrations of the air, distinguishable according to their duration, or to their force (that is, loudness), or else to a certain proportion of the sounds to each other, in a scale of which the relative portions are called in English high or low, and in French grave or aigu. 455. Where this relation is not perceptible to the ear (though the loudness and duration of the sounds may be so in a great degree), we call the sound noise, answering to the French word bruit; but where the relation is perceptible, it may be best illustrated by the example of an elastic string or chord, stretched between two points A and C, Traité d'Acoustique, p. 5. * Outlines of Hum. Physiol. p. 370, B thus: A D C. Now if the chord A C be drawn at its middle point to B, it will form an arc or curve line A B C; and if then let loose, the motion which it has acquired will carry it to D, so as to form an arc A DC, and thence it will be forced back again toward B. Each of these motions is called a vibration, and every vibration giving an impulse to the air produces a sound. The successive vibrations become less and less, till the line rests in its first position. The number of vibrations which occur in a given time determines the pitch of the sound: and the frequency of the vibrations depends on the length of the arc; if short they are frequent, if long they are few. When the arc is long, the sound is what we call low; when the arc is short, the sound is what we call high. It is obvious that the length of the arc may be increased or diminished either by a minute and imperceptible gradation in the nature of a slide, or else by adding or deducting certain definite and proportional parts; and that the sounds caused by the vibration of those arcs will vary in like manner. The former of these circumstances takes place in ordinary speaking, the latter in singing and in music generally. For the sliding elevations and depressions we have no strictly accurate name, but the definite intervals we call, in music, notes. The late Mr. Steele, in an ingenious essay on the measure and melody of speech, endeavoured to reduce the spoken rise and fall of sounds to a sort of musical notation, but with very partial success. 66 456. The power of the human ear in distinguishing sounds by the Power of disvibrations has certain limits. "In the gravest (i. e. lowest) sounds tinguishing. perceptible to the human ear, says Chladni, the sonorous body makes at least thirty vibrations in a second; and we are able to appreciate sharp (i. e. high) sounds in which the vibrations are from 8,000 to 12,000 in a second." Musical notes, it is known, rise by octaves, each of which is produced by double the vibrations of the preceding. The lowest note of the violoncello has 128 vibrations, the octave next above it 256, the third 512," &c.† The range of the voice seldom exceeds two octaves and a half; Dr. Bennati says his own voice extended to three octaves; so did Zelter's; and Catalani's reached to three and a half.‡ The action of the small muscles which cause these vibrations, is clearly shown in Mr. Willis's tabular statement above quoted; and thus the quality of voice called its pitch, has been fully explained. The time of a vocal sound is also susceptible of measure; and the general perception of measure, or, as it is sometimes called, of rhythm, is a source of great part of the pleasure of poetry, and furnishes the rules of prosody, which are commonly deemed a part of grammar. A long or short sound, too, in most languages, serves to distinguish one part of speech from another, and * Traité d'Acoustique, p. 6. + Ibid. p. 7. Müller, p. 1031. Epiglottis. How made articulate. Vowels. one noun from another noun, or one verb from another verb; and in all these respects the quantity of a word (as grammarians call it) is material to the understanding of language. Independently of these latter considerations we may observe, that by the combined effect of the pitch of a vocal sound, though wholly inarticulate, with its duration and loudness, human feelings are expressed, in infancy, or in a state of barbarism, or of great excitement. Under such circumstances, the sound forms what Mr. Majendie calls a cry, and considers as common to man with brute animals. To connect feeling with conception, recourse must be had to the power of articulation. 457. I have stated that the glottis has a moveable cover called the epiglottis. In the act of carrying food from the mouth through the pharynx into the œsophagus for digestion, the larynx is raised, and the epiglottis brought down on it, so as to prevent the food from passing into the glottis. If any extraneous matter which is large passes into the glottis, there is danger of immediate suffocation; if 'small, it may pass into and lodge in some of the bronchial passages, causing eventual inflammation of the lungs, and in course of time death. If a person imprudently laugh, or attempt to speak, while he is swallowing, or holding any loose substance in his mouth, the escape of air from the lungs lifts up the epiglottis, and one or other of these pernicious consequences may ensue. To a similar cause was owing the remarkable accident of Mr. Brunel, which in a manner still more remarkable, was relieved by the skill of Sir Benjamin Brodie. A half sovereign had remained for some weeks in a part of Mr. Brunel's bronchial tube, when Sir B. Brodie, causing him to be fastened on a board which moved on its centre, reversed the position of his body; and the coin, by its own weight forcing open the glottis, passed into the mouth. 458. In uttering a vocal sound, the epiglottis being raised, the air passes into the pharynx, which is a large cavity with an opening into the mouth, and another into the nose, and both of these contribute to render the sound articulate. The oral passage is the principal. Through that, the air is capable of passing directly and in an undiverted stream, producing those sounds which the ancients called vocales, and we call vowels, or else interrupting the stream, so as to produce what are called consonants. I shall consider these first in their simple, and then in their combined effect. 459. In the production of vowel sounds, the cavity of the mouth is capable of assuming different forms according as it is varied by the action of the throat, palate, tongue, teeth, or lips; and hence follows a correspondent variety in the vocal sounds, the number of which different writers estimate differently. It is true that, theoretically speaking, there can be no precise rule for fixing the possible distinction of vowels at a certain number, because the action of the organs may be indefinitely varied, according to the natural constitution of every human being, at every stage of his existence. All that can well be done in the present state of science, is to adopt such divisions of vowel sound as are, or have been, in use among those nations whose practice in this respect we are able to ascertain. In this view I have found no statement more reasonable and practical than that of Bishop Wilkins, who says, "There are, I conceive, eight simple different species of vowels easily distinguishable whose powers are commonly used. I cannot deny but that some other intermediate sounds might be found, but they would, by reason of their proximity to those others, prove of so difficult distinction as would render them useless."* The eight distinctions of the learned bishop appear to be suitable to the Greek and Latin languages, and the different branches of the Teutonic, Scandinavian, and Celtic, with which I have any acquaintance; how far they may serve to express the vowel sounds of other nations, I pretend not to say. The Bishop expresses them by the following marks-y, a, a, e, i, o, w, u. I take them in this order, because the operation of the different organs will thus be best seen, beginning with the sound as it enters from the larynx, and proceeding gradually to the lips; and I shall explain them (as well as the consonants hereinafter noticed) according to the Bishop's statement, corrected in some important particulars by the suggestions of Sir B. Brodie. It is to be observed that every one of these vowels may be long or short; that is, its pronunciation may occupy a greater or less portion of time, but this does not depend on articulation. The oral cavity continues to retain the same form during the whole utterance, and the time, as has already been shown, is a circumstance depending on the action of the lower organs. i. y is a guttural sound, for which we have no mark in English, but which is expressed in Welsh by this character. It is produced immediately at the emission of air from the throat; the teeth are a little separated, the muscles of the tongue are relaxed, the tip of the tongue is a little below, and the posterior part of the tongue is a little above the level of the teeth; the lips in this (as in all the vowels) are of course open. The long sound is frequent in French, as in beurre, meurtre; it is less long in English, as in bird, burthen, and short, as in but, nut. Being so very simple in its formation, many of our other vowels, when short, degenerate into it; and indeed this circumstance may be almost considered as a characteristic of English pronunciation, especially in rapid speaking, for in such a case the words honour, of, father, sir, are pronounced as if they were written honyr, yv, fathyr, syr, &c. ii. " A❞ (says Wilkins) "is the most apert amongst the Linguapalatal vowels. 'Tis expressed by this character, because being one of the Greek letters it is more commonly known. It is framed by an emission of the breath betwixt the tongue and the palate, the tongue being put into a more concave posture, and removed further off from the palate." Hence the oral aperture is larger than in the preceding vowel y; the teeth are separated to a greater distance, the tongue is *Real Char. P. 3, c. 11. |