Voice (Lat. vox), an audible sound produced by the larynx, and affected by its passage outwards through the mouth and other cavities (see LARYNX, PALATE, SOUND). When so modified in particular ways it becomes speech or song. The main differences between these two latter are that speech is more limited in compass or pitch, that it is less sustained in respect of pitch, and is not confined to the notes of a musical scale, that it is associated with a less clear or open passage for the breath, and that it presents certain utterances (consonantal, aspirate, guttural, &c.) which have not a purely musical character. The larynx is the organ by which the so-called vocal sounds (or primary elements of speech) are produced; and it was in former times keenly debated to which class of musical instruments the larynx might best be compared. As Dr Witkowski says (Mechanism of Voice, Speech, and Taste, Lennox-Browne's translation): 'Galien compares it to a flute, Majendie to a hautboy, Despiney to a trombone, Diday to a hunting-horn, Savart to a bird-catcher's call, Biot to an organ-pipe, Malgaigne to the little instrument used by the exhibitors of Punch, and Ferrein to a spinet or harpsichord. The last named compared the lips of the glottis to the strings of a violin; hence was given the name Vocal Cords, which they still retain. The current of air was the bow, the exertion of the chest and lungs the hand which carried the bow, the thyroid cartilages the points d'appui, the arytenoids the pegs, and lastly, the muscles inserted in them the power which tensed or relaxed the cords.' But the vocal cords are very different in their structure from strings, and no string so short as the vocal cords are could produce a clear bass note. They more resemble in their action a pair of reeds; not such an instrument as a clarionet, in which the vibrations of the column of air of any determinate length overpower the single reed, and compel it to vibrate only in rhythm with themselves, but such an instrument as may be constructed with two strips of india-rubber laid across the mouth of a wide tube so as to present a mere chink between them. But the larynx contains within itself a great power of adjustment, such as is possessed by no musical instrument; the tension of the vocal cords can be varied; the vibrating portion of the vocal cords can be shortened; the distance between them can be varied; their form can be altered, as by blunting their free edges or by flattening their whole structure; and they can be prevented from vibrating in their whole breadth, the vibrations being then confined to their margins merely: and these adjustments may be combined so as to suit different pressures of air from the lungs. Further, above and below this primary sounding apparatus there are adjustable cavities, which act as resonators, and thus (see SOUND) affect the quality of the sound produced. The actual action of the larynx as a sounding instrument has only been clear since Garcia introduced (1855) the laryngoscope (see LARYNX) as a means of observing what went on during actual vocalisation; and a flood of light has been thrown on the subject by the researches of Czermak, Merkel, Madame Seiler, and Behnke. The crico-thyroid muscles pull the thyroid cartilage and the cricoid cartilage together; the vocal cords are thus tightened: and the posterior crico-arytenoid muscles aid in this. The thyro-arytenoid muscles relax the vocal cords, and twist the arytenoid cartilages round so as to make their attachments to the vocal cords come over towards one another instead of lying at some distance from the middle line; and they can also so act as to press portions of the vocal cords together, and thus shorten the free vibrating edges; and further, they can squeeze their own inner portions thin, and thus flatten and thin the vibrating part of the vocal cords. The posterior crico-arytenoid muscles, in addition to aiding in tightening the vocal cords, twist the arytenoid cartilages so as to widen the back part of the chink between the vocal cords; while the lateral crico-arytenoids as well as the thyro-arytenoids perform the reverse operation, and thus narrow the chink, and are assisted in this by the arytenoidens muscle, which directly pulls the arytenoid cartilages together. These muscles in combination effect the various adjustments above spoken of. In a state of rest the glottis lies open, and respiration is unimpeded; in deep breathing the chink is still wider, but as soon as we wish to utter a note the two arytenoid cartilages rapidly approach one another, and the glottis-chink is narrowed. At the same time the superior or false vocal cords approach, but never touch one another. If the vocal cords meet one another before the current of air flows to produce the tone, there is a disagreeable jerk or click at the commencement of the note; if the air flows before the vocal cords have sufficiently approximated, there is an aspirate, and the 'attack' or beginning of the note is uncertain; the two actions ought to coincide in time, and then the 'attack' is clear and precise, for the vocal cords are brought to the right place for vibration at the very time when the air begins to tend to set them in motion.
In different larynxes much depends on the relative sizes of the vocal cords; thus a man with a bass voice has longer vocal cords than a child or a woman; but as between basses and tenors, tenors and contraltos, or contraltos and sopranos, the higher voice may sometimes appear to have the longer vocal cord: on the other hand, slenderness of structure makes up for greater length, and when the vocal cords are long and slender, the voice is 'flexible,' for the cords readily enter into vibration. Further, a narrow larynx is conducive to high pitch, and so is not only the size but also the form of the female larynx, in which the upper part, above the false vocal cords, and between them and the hyoid bone, is comparatively flat. In children the larynx is small, and the voice high-pitched; but the larynx grows very rapidly at puberty; and as its different parts do not then grow with proportionate rapidity, the muscular control is uncertain, and the voice, especially in boys, breaks.
In one and the same larynx different parts or regions of the scale are produced by different laryngeal mechanism: and those notes of the scale which are produced by the same mechanism (Belincke) are said to be produced in the same register. The registers of the voice have given rise to a great deal of discussion, most of which appears to have arisen from independent attempts to express sensations in words. It appears, however, from the laryngospectral evidence (for which see Lennox-Browne and Belincke, Voice, Song, and Speech) that the whole mechanisms can be divided into three groups, or 'thick,' 'thin,' and 'small' registers, as Mr Curwen happily named them before the laryngospectral evidence had come to hand. In the first the vocal cords vibrate as thick masses; in the second they vibrate in their thin edges only; in the third the vibrating chink of the glottis is much reduced in length. The lowest or thick register usually extends through the interval in bass voices, through in tenors, in contraltos, and in sopranos. Very curiously, it thus terminates at the same note in all voices. This register is usually divided into lower thick and upper thick. The 'lower thick' usually extends through in basses, in tenors,
in contraltos, in sopranos; and in this and does not division the vocal cords are go beyond very bulky and thick, the posterior portions of the arytenoid cartilages are closely approximated, but the chink is wide and elliptical in the lower notes, less so in the upper; and the false vocal cords are far apart. In the 'upper thick' the arytenoid cartilages have rotated into complete contact with one another, so as to shorten the vibrating portion of the vocal cords: the thyroid bends down on the cricoid cartilage; the vocal cords are being stretched so that the chink between them is very narrow; and the epiglottis rises as the pitch rises. When the upper limit of this register has been reached the strain on the parts is extreme. Beyond this register comes the thin (the 'male falsetto'), which is in the female the normal mechanism for notes between
The strain of the chest-notes, or thick register, is now relieved: the thyroid cartilage returns: the vocal cords lie still and somewhat slack at first, and the vibration is confined to their membranous edges: they are separated by a narrow chink which is at first longer than before: as the pitch rises the crico-thyroid muscle goes on acting until the thyroid and cricoid cartilages are again in apposition: and this lasts, in tenors, contraltos, and sopranos alike, through the interval
When the note C is reached still higher notes are attained by a gradual shortening of the vocal chink, which becomes elliptical, and is gradually reduced in size. But beyond F or F# the soprano voice has still another register, the 'small' register. In this only the front part of the vocal cords vibrates; the vocal chink is reduced to a small aperture in front, which contracts as the pitch rises, while the hinder portions of the vocal cords are pressed tightly together. These different mechanisms produce perceptibly different qualities of tone; and the art of the vocalist is, largely, to use higher registers for lower notes, so that he may be able to strike the same note in more than one way, and thus have at command the means of smoothly passing from one part of the scale to another without jöddelling or appearing to sing with different voices on different notes. One means of doing this in some cases is by the use of a voix mixte, in which the laryngeal position of the lower thick register is associated with the vibrating mechanism of the lower thin. For voice-production and voice-cultivation reference must be made to the special manuals mentioned below.
The resonating cavities and apertures connected with the larynx form a complex system consisting of the pockets lying between the true and false vocal cords (the effect of which cannot be very great, but which must be affected by the position of the false vocal cords), the vestibule of the larynx, the epiglottis (which directs the sound-waves towards different parts of the resonating system, and affects the colour or timbre of the tone produced), the pharyngeal cavity, the nasal cavity, and the mouth. When the sound-waves find a clear air-way over the tongue and under the soft palate the tone is clear; when the soft palate hangs down, so that some of the air escapes by the nose, the tone is nasal; when the tongue does not lie flat and out of the way the tone is throaty and strained; when the lips obstruct the sound-waves the tone becomes muffled. The quality of tone is also very much affected by the control which the speaker or singer may have over the breath: he should have his lungs well filled with air by abdominal respiration, and be able to attack the sound clearly with a minimum expenditure of breath, and direct the sound-waves well forward, keeping the resonating cavities large and clear; under these circumstances the voice carries through a maximum distance with a given effort, especially if, in the case of a speaker, he raises not the pitch of his voice, but its loudness when the occasion requires it: and under such conditions the pressure of air in the windpipe can be raised to a considerable height, and the voice rendered clear and telling without exhausting exertion.
Modifications in the form of the resonating cavities result, by resonance, in those modifications of timbre (or the relative predominance of particular harmonics of the fundamental note; see SOUND) which we call vowels. In pronouncing u (= oo or Italian u) we round the lips and draw down the tongue, so that the cavity of the mouth assumes the form of a bottle without a neck; if the lips be opened somewhat wider and the tongue be somewhat raised, we hear o; if the lips be wide open and the tongue in its natural flat position, we hear a; if the lips be fairly open and the back of the tongue raised towards the palate, the larynx being raised at the same time, the vowel produced is e; and if we raise the tongue still higher and narrow the lips, we hear i. Each of these resonance-chamber forms has its own dimensions and its own resonance-pitch; and of these u has the lowest pitch, as may be heard by whispering the vowels, or by means of a series of tuning-forks successively reinforced by the cavity of the mouth as a resonator; for which reason it is easier to sing u and o on low than on high notes. Diphthongs are produced by continuing the laryngeal sound during the transition from one vowel-mouth-form to another. Consonants are produced by various interruptions, total or partial, of the outflowing stream of air. If the air be completely stopped by the lips and soft palate, we have p when the obstruction is suddenly removed; the same action, accompanied by a certain continued sound in the larynx, and a heavier air-pressure within the mouth, gives b; if the air be checked by the lips, but not by the soft palate, so that it passes through the nose alone, we have m; if it be checked by the soft palate and by bringing the point of the tongue to the front of the palate, or to the gums, we have t; the same with continued laryngeal sound and greater air pressure gives d; the action for d, modified by allowing a little air to escape over the soft palate through the nose, gives n; if the air be checked by the soft palate and by bringing the middle or back of the tongue to the arch of the palate, we have (silent) k and (if there be laryngeal sound) g; the latter, but with the nasal passage open, gives ŋg. In other cases a continuous stream of air is made to escape under some pressure past an obstacle, and thus to sibilate; if it be driven through a narrow clink between the upper front teeth and the lower lip, the larynx being silent and no air escaping through the nose, we have f; the same, with greater air-pressure and a laryngeal sound, gives v; the true aspirated p and b (air driven with or without voice through a very narrow and small lip-clink) do not exist in English, but the latter fairly represents the German w in wasser; if the tongue be pressed tightly against or between the front teeth and air be driven through these, we have, without voice, th in thin, or with voice th in then; if in the last instance the contact be loose, we have s and z respectively; if the tongue be put in the t position and a little reverted, we have for tight contact ch and j (judge), and for loose contact sh and zh (French juge); if it be put in the k position we have for loose contact, voiceless, the Scotch ch in loch; if in the ŋg position, the Dutch ch, voiced, in which the soft palate vibrates, and the Welsh ch, voiceless. In l the tip of the tongue is fixed, and its sides oscillate, while a laryngeal tone is being produced; in the Welsh ll the position and action are the same, while a strong current of air is employed, and the larynx is silent. In r the tip of the tongue vibrates against the front teeth so as intermittently to shut off the air-stream, while laryngeal tone is maintained; in Welsh rh, as in Rhyl (Greek ῥ), the action is the same, with a strong current of air and larynx silent. In a 'burred' r (Northumberland, Parisian French, North German) the air is interrupted by vibrations of the soft palate. The aspirate h is produced by narrowing the air-passages, by raising the tongue and using a momentary strong current of air at the beginning of the vowel. It not unfrequently happens that there is difficulty experienced in co-ordinating the requisite movements of larynx, tongue, and mouth, which are usually automatic, and depend upon the will to attain, by imitation, a given result; in such a case a person stutters his consonants or stammers his vowels. In many such cases the respiration is not under control, and attention to this may enable the defect to be remedied.
The reader may consult Behnke's Mechanism of the Human Voice, or Browne and Behnke's Voice, Song, and Speech, and books there referred to; and also G. Holmes, Vocal Physiology; A. Semple, The Voice; Von Meyer's Organs of Speech; C. Lunn's Philosophy of Voice; Tucker's Vocal Sounds; A. B. Bach's Principles of Singing; W. H. Walshe, Dramatic Singing Physiologically Estimated; Sir Morell Mackenzie, Hygienic of the Vocal Organs; G. Durant, Hygiene of the Voice; John Hullah, Cultivation of the Speaking Voice; Holder's Elements of Speech; Bell's Visible Speech; Czermak, On the Laryngoscope; Gavarret, Phonation et Audition; Helmholtz, The Sensations of Tone (trans. 1875); the article PHONETICS, for voiced and unvoiced consonants; and for figures produced by the voice (as on moistened glass plates), Mrs Watts, Voice Figures (1891). See also THROAT (Affections of the).