the higher notes, the larynx rises, the laryngeal muscles being contracted for this purpose and the head thrown back; while, for the lower notes, the larynx descends and the chin is depressed. These are well-known movements, and a patient examined with the laryngoscope is sometimes made to utter high notes, because exploration of the larynx is more readily performed when it is elevated. Attempts have been made to explain these phenomena by comparing them with those produced in wind-instruments. In the first instance, the part under the glottis was supposed to be elongated, and the part' above the glottis contracted, and vice-versû, in the second or emission of high notes. This explanation, however, is rendered useless by the fact that the same phenomena are observed when we produce the sound in inspiration; thus, although the physical performance of the organs is reversed, the larynx always rises in the upper notes and falls in the lower.

The elevation of the larynx may be much more satisfactorily explained by considering that the walls of the trachea act as a resonant organ, and that, consequently, in order to heighten a certain sound, they must be in a state of peculiar tension, for the same elastic wall does not vibrate indifferently with all sounds: its tension must be modified in differ⚫ent cases. The higher the note, the more tense the resonant parts are.

The entire nasal system, consisting of the nasal chambers and the frontal, ethmoidal, and maxillary sinuses, is connected with these organs of sound. These cavities are not intended for secretions; but, on account of their coats being formed of somewhat delicate elastic lamellæ, they readily vibrate. Any injury to these organs considerably modifies the tone of the voice. The cartilages of the nose are also resonant organs, as everybody knows that when they are hindered from vibrating the tone of the voice is altered in a peculiar

manner.

The vibration of the trachea, the bronchi, the lungs, and the cage of the thorax, also serves to intensify the sounds produced by the larynx. The voice undergoes a change in diseases of the trachea, the bronchi, and the lungs.

The articulation of speech, which differs greatly from the simple cry, or sound made by the larynx, are almost entirely produced by the working of these sonant parts, and chiefly by modifications in the apertures of the lips and the back part of the throat.

Voice and Speech. The sound produced at the glottis is only an inarticulate sound, differing only in intensity, pitch, and tone; yet this glottid sound, by the re-enforcement of certain of its characteristics at the buccal and nasal cavities, and by the union with other sounds produced at these points, acquires special features constituting the voice and speech properly so-called (see Organs of the Senses (Hearing) for the explanation of the words intensity, pitch, tone, sounds, etc.).

The intensity of the sound produced in the glottis depends on the force with which the expiratory current of air strikes the edges of the glottis when so arranged as to emit any decided sound; this intensity depends essentially on the development and the elasticity of the lung, the breadth of the thoracic cage, and the force of the expiratory muscles.

The pitch of the sound produced by the vocal lips increases in proportion to their length and tension (or contraction); thus the human voice performs the gamut or scale in passing from the lower notes to the higher; it even forms two series of scales, the lower of which is generally designated under the name of chest register (chest voice), and the sharper and higher under that of head register (head voice). These expressions have no meaning in a physiological point of view, since the voice is formed in the glottis in both cases; but what has given rise to them (and, in a certain sense, justifies the use of them) is the sensations experienced during the emission of either the so-called head or chest voice, the accompanying vibrations being more strongly marked in the walls of the chest in the one instance, and in the supra-laryngeal cavities in the other. According to Mandl, the essential modification in the glottis which produces the emission of sounds in the two registers, consists in the fact that, in the case of the chest voice, the orifice of the glottis is open and vibrates throughout its whole extent, while in that of the head voice (or falsetto) the orifice is open and vibrates only in the interligamentous part; the entire intercartilaginous portion is then closed, while the superior vocal cords sink, and are adjusted to the inferior cords, covering a considerable part of them in such a manner as to diminish the extent of the vibrating part (an effect resembling that produced by the tongues employed in the pipes of an organ).1

The human voice has, therefore, generally a range of two

See also Ch. Bataille, "Nouvelles Recherches sur la Phonation." Paris, 1861.

octaves, and according to whether these two octaves belong to the upper or lower part of the scale of musical sounds, the human voice has been classified, beginning with the lowest, into the bass voice (from fa to re,), the barytone (from la to fa), the tenor (from do, to la,), the contralto (from mi, to do), the mezzo-soprano (from sol, to mi,), and the soprano (from si, to sol), the three latter being women's voices. The differences between them are principally owing to variations in the length of the lips of the glottis; this length is represented in man by the number 25, in woman by 20, and by 15 in eunuchs, their voice being extremely high.

A child's voice is very high, the glottis being smaller than that of the adult. The change in the voice takes place at the age of puberty, the development of the larynx causing the voice to become an octave lower in the case of boys, and two notes only in that of girls. In old age, the ossification of the cartilages, and the atrophy of the muscular fibres (?) cause the voice to become still lower, while its intensity is also diminished; thus tenors become barytones (L. Mandl).

The tone of the voice is first produced by the lips of the glottis itself. Helmholtz has, we know, demonstrated that the tone (see Organs of the Senses, Hearing) is due to the fact that the sounds which appear to us so simple are really composed of a fundamental note, and several accessory netes, called harmonics (Sauveur). The varied combination of these harmonic notes, in different instruments, constitutes their special tone. The vocal lips, like the membranous pipes, beside the fundamental vibration of one sound, exhibit partial vibrations which give rise to various harmonics of this note: whence the different tones of the note produced by the glottis. What, however, especially marks the tone of the voice, is the manner in which these harmonic notes are reinforced in the cavities and vibrating edges above the glottis (the pharynx, mouth, nasal chambers, etc.), so as to impress their peculiar features upon the voice (see p. 357).

By studying these harmonic notes as being the means by which the tone of the voice is produced, Willis, Wheatstone, Donders, Du Bois-Reymond, and especially Helmholtz,1 have

1 See Helmholtz, "Théorie Physiologique de la Musique." Trad. fran par Guéroult, Paris, 1868.

Laugel, La Voix, l'Oreille, et la Musique." D'après les travaux de Helmholtz. In "Revue des Deux-Mondes." Mai,

been enabled to discover the mechanism by which the vowels are produced. The vowels are essentially notes produced by the passage of the air through the pharyngeal and buccal cavities; these are arranged in a special manner, and, consequently, resound differently as each vowel is pronounced. When a vowel is pronounced in a whisper, the glottis takes no part in the process, the sound being produced simply by the passage of the air through the supra-glottidal cavities, which at that moment are so arranged as to give utterance to the vowel in question; when the same vowel is pronounced aloud, the supra-glottidal cavities, arranged as before, produce the effect of reinforcing those harmonics existing in the sound made in the glottis, which exactly correspond with those of the vowel to be pronounced. In other words, the buccal and pharyngeal cavities act as sounding boards, which may be variously harmonized.

We cannot carry this analysis any farther here; it belongs to the domain of pure physics, and we will only add that the form assumed by these cavities for the utterance of the different vowels, has been clearly ascertained, and that when the cavities are properly arranged, if the wind from a pair of bellows be made to pass before the mouth, even though the breath be held back, sounds are heard exactly resembling vowels pronounced in a whisper. In general it may be said that "the longitudinal diameter of the pharyngo-buccal cavity is reduced, and its transverse diameter increased by the vowel-sounds ah, a, and e (a, e, i); while in pronouncing the vowel-sounds o and u, the longitudinal diameter is increased and the transverse diameter diminished. The movements of the different parts of the cavity follow this general disposition. The lips make a horizontal movement, which is more and more decidedly antero-posterior in the case of the three first vowels, and anterior in that of the two latter. In pronouncing o and u, the tongue is drawn backward, while in a and e, it is more or less thrown forward. The movements of the cheeks, the velum of the palate, the uvula, and the pillars of the fauces, all unite in carrying out this general arrangement, etc. etc." (Mandl, op. cit.).

The consonants, which form the second element of articulate speech, are not sounds, like the vowels, but rather irregular vibrations, too confusedly mingled to be separately distinguished (see Hearing); they are sounds which cannot be distinctly heard by themselves, but differ by the manner in which they begin or finish the utterance of a vowel. The

consonants, therefore, can only be pronounced by being joined with a vowel, whence their name (cum sonare). When a vowel is uttered, the cavities of the mouth and pharynx are so arranged as to present certain obstructions to the air which produces the vowel, and the interruption to these latter causes the more or less loud sound of the consonants.

The consonants are labial, lingual, or guttural, according as the obstruction is found in the lips, the tongue, the velum of the palate, or the pharynx; and in accordance with the force employed to overcome the obstruction, whether by a sort of explosion, by vibratory friction, or by a trembling movement, we have explosive labials (b, p), resonant labials (f, v, m), and trembling labials (the lingual r); explosive gutturals (k, g), resonant gutturals (j and ch, especially in German), and trembling gutturals (the guttural r). In some languages, especially the Arabic, the gutturals are very marked, as, for instance, the sound which we designate as ha, and which appears to be produced by some obstacle situated as low down as the glottis. It was while seeking to discover the mechanism by which the really guttural sounds of the Arab tongue are produced that Czermak invented the laryngoscope which is now so universally employed for the exploration of the larynx.

The labial consonants, especially the explosive labials (b, p, m), are the most easy to pronounce, on account of the simplicity of the movements required: they are the first uttered by children (papa, mamma, etc.), and are those which are most easily taught to certain animals, and are naturally produced in bleating (L. Mandl).

This combination of phenomena, by means of which a sound is uttered by the glottis, modified by the pharyngeal and buccal cavities in such a manner as to represent a vowel, and joined to certain sounds, produced in the same cavities, and which form consonants, serves to constitute the articulate voice, while the intelligent combination of vowels and consonants in syllables, and of syllables in words, constitutes speech. In spoken words, the variations in pitch of the syllables are not strongly marked; in singing, on the contrary, the syllables, especially the vowels, which form their essential element, are produced with considerable and harmoniously arranged variations in pitch.

Innervation of the Laryngeal Organ. The organ of phonation of the larynx is dependent on the inferior laryngeal nerve, which appears to come from the pneumo-gastric,