come together, the tongue relaxes, and the current of air dams up behind the closed lips. Finally the lips open, and with a little explosive noise, the air escapes. The word "gap" has been spoken.
It must be clearly understood that each initiation and cessation of activity is carried out under the timing pattern and sequence of volleys of nervous impulses from the brain. Moreover, each of these activities involves speech structures that are paired. In one sense we can be said to have two tongues and four lips, and two of all the speech muscles. Those muscles on the right side of the body receive their nervous impulses from the left side of the cerebral cortex; the muscles on the left, from the motor areas on the right side of the brain. And yet, if such structures as the tongue are to work as units, it is obvious that both halves must get the appropriate impulses at the same instant. Experimentation has shown that this is exactly what happens in normal speech, although in stuttering the paired muscles frequently do not receive their volleys at the same time or in the same amount. The coördinating agency which compels the motor areas on the two sides of the brain to send equivalent volleys at the same time is thought to reside in the side of the brain opposite the preferred hand. In view of the complexity of the speech act, then, we can only wonder that there are so few speech defectives. As one phonetician phrased it, "If you want to perform a miracle, say the word 'pup.'"
1. Avery E., Dorsey J., and Sickels V. A., First Principles of Speech Training, Chapter 2, New York, D. Appleton-Century Co., 1931. A discussion of the physical and physiological bases of speech, including the physical properties of sound, the breathing apparatus, the speech mechanism, and the ear. Anatomical drawings of parts of the respiratory organs and the speech organs are included.