This series of psycho-physical processes may be figuratively called the main trunk line of speech, but the following accessory processes are equally essential. The muscular movements not only produce air vibrations, but also stimu late by pressure of friction sensory nerves lo cated in or upon the muscle fibres, in the syno vial membranes of the joints and in the sur faces of the tongue, palate, gums, lips, etc. This stimulation results in (4) kinesthetic sensations (of strain, deep pressure and touch) which re port to us the location, nature and extent of the movements executed. Aided by the audi tory sensations they provide a means by which we control our movements ; through them we learned to repeat desired movements in infancy; through them we become aware of errors of movement (mispronunciations) in later years; without them tradition in language would be impossible.
Not less vital are (5) the many associational processes. The parts of the brain active during thinking are connected (directly or through sub centres) with the motor areas, and it is a law of mental life that all thought tends to pass over at once into action. There is likewise asso ciation between the sounds of the words and their meaning, between the sounds and the kinesthetic sensations, between the kinesthetic sensations and the ideas, between the visual sensations (that is, the appearance of the written or printed words) and the meaning, etc. The effect of these associations is to bind the whole into a co-ordinated and harmonious system, in which each process takes place with a degree of accuracy and order of sequence adequate to the accomplishment of the purposes for which speech is employed.
All the above processes both in man and animals have been developing since primaeval times by a natural process of evolution in accordance with the laws of physical and mental growth. On the other hand alpha betic signs or letters are arbitrarily de signed or selected by individuals to represent certain sounds. They yield (6) visual sensations. Although originating as symbols of sounds, the letters when grouped into words quickly be come associated with the meanings and are primarily symbolic of them.
Thus we see that speech is a combination of three different kinds of symbols : (a) the primary symbols, muscular movements, (b) the secondary symbols, speech sounds, and (c) the tertiary symbols, written or printed words. The average man thinks usually of the last two forms, but he who would understand the nature of language and fathom the laws of its devel opment should rather direct his attention chiefly to the muscular movements and regard language study as applied Psychology of Movement.
The above described processes beginning with thought in the mind of the speaker and ending with the awakening of thought in the mind of the listener do not, however, complete the cycle of speech. It must not he forgotten that speech is a social activity. Man cannot live without the co-operation of his fellow-men. The chief purpose of speech is to secure this co-operation and thus achieve 'some form of self-realization, of accomplishing our desires. The communicative process is completed only when the speaker gets a response by word, look, gesture or even silence (for silence is some times eloquent), which will enable him to judge the attitude of the listener and hence the degree of his own success or failure. *
The problems of General Linguistics fall into two classes: first, those which have to do with the processes of expression and, second, the problems of understanding. Under the first fall the following: the relation of thought to lan guage, the relation of physical to spiritual mat ters, the origin'of language, the degree of accu racy and completeness with which language ex presses thought, the extent to which the forms of thought are controlled by language and vice versa, the effect of environment on speech, the problems of anatomy and physiology of nerve and muscle and of the localization of brain functions, the problems of muscular control. The problems of interpretation include those of understanding and those of sensation. Here fall the questions as to the degree of accuracy with which sensations correspond to stimuli, or, conversely put, how far the state of mind determines the character of the sensation (mis hearings, misreadings and misunderstandings), how sensations awaken thought. All these problems may be grouped under two heads: Phonetics and Semantics.
Phonetics is the general science of speech sounds; phonology is the study of the system of sounds of any given language, as, e.g., English phonology. The organs of speech in the narrower sense are the mouth and nose cavities and especially the tongue and larynx; also the trachea and lungs with their controlling muscles. In a broader sense they include those muscles of the abdomen which aid in the control of breathing. The lungs force through the trachea •a stream of air, the rate of flow and compression of which are varied from moment to moment to meet the needs of speech. The larynx, which rests on the top ring of the wind pipe, is a small box having a cartilaginous framework overlaid with muscles, connective tissue and mucous membrane. Its most essential parts are the so-called cords .° These are not, strictly speaking, cords at all, but are overhanging, ledge-like projections, one arising from each side of the inner wall of the larynx. The core of each is formed by a small muscle, the front ends are immovably attached to the inner front angle of the thyroid cartilage (Adam's apple) in contact with each other. Each muscle is attached at its posterior end to one of the arytenoid cartilages, which can be moved by means of appropriate muscles up ward, downward, forward or sidewise. Thus by the approximation of the arytenoid cartilages the °cords' can be brought into contact along their entire length, completely dosing the glottis, as the opening between them is called; or the rear ends of the cords may be separated, yield ing a V-shaped glottis. When brought into contact, or nearly so, and tensed by proper muscular action, they are made to vibrate by the current of air forced through the trachea. The vibrations can be easily felt if the finger be placed upon the Adam's apple during speech.