The vibration of the vocal cords makes the column of air itself vibrate, and the vibration is communicated to the air in the upper part of the throat, the nose, and mouth, from which finally it issues as sound. The vocal cords are the "reeds" of the vocal instrument, and as, owing to the extraordinary number and intricate arrangement of their muscular fibers, they can change their length and shape and thickness in an almost infinite variety of ways, they are equal in effect to many different reeds. If the vocal cords can not move so as to bring their edges almost into contact, or if there is any substance between them which prevents them from coming together, the voice is destroyed; if there is anything (such as a growth) in or on one of them, its vibration is more or less checked, and hoarseness is the consequence. The primary sound generated in the larynx is modified by the shape, size, and density of the parts through which the vibrating column of air has to pass before it issues from the "barrier of the teeth." These "resonators," include the part of the larynx above the vocal cords, with the little sounding-board, the epiglottis, covering it; the upper part of the throat or pharynx, the nasal passages with certain echoing caves in the bones of the skull which communicate therewith; and the mouth, with the soft palate and uvula, tongue, cheeks, teeth, and lips. It is to these resonators, as well as to the size and shape of the larynx itself—and those parts, like the features of the face, are never exactly similar in any two individuals—that the distinctive quality, or timbre, of the voice is due.
Timbre is the physiognomy of the voice by which the speaker can be recognized even when unseen. Just as the face may be lit up with joy, darkened with sorrow, or distorted with passion, so may the voice be altered by strong mental emotion. This is due to the influence of the mind on the nervous system, which controls every part of the body: if it be stimulated, increased action will be excited; if disordered by shock, feeble irregular movements will be produced, the limbs will shake, and the voice tremble. From the effect of peculiarities of physical conformation on the voice it will be readily understood that timbre may be, in some degree, a national or racial peculiarity. There are also certain physical types which correspond to particular timbres of the voice. I have noticed this particularly in persons of like complexion even when different in race. Thus, a certain sharp metallic clearness of articulation is often found in individuals of ruddy complexion, light yellow hair, and hard blue eyes, while rich, mellow tones, with a tendency to portamento in ordinary speech, are often associated with black hair and florid face. A remarkable point is that the same voice may be altogether different in timbre in singing from what it is in speaking. The difference is probably due to the fact that in singing the resonators are, instinctively, or as the
