All that has been said of muscular stiffness applies with especial force to the vocal organs. Like the rest of the muscular system, the muscles of the vocal organs are arranged in opposed pairs and sets. The contraction of all the muscles of the throat, each opposed set or pair exerting about the same degree of strength, causes a condition of throat stiffness. Singing is possible in this condition. But the singer's command of the voice is not so complete and satisfactory as under normal conditions. Throat stiffness does not altogether deprive the vocal organs of their faculty of instinctive adjustment in obedience to the demands of the ear. To a fair extent the voice is under the command of the singer. The vocal cords adjust themselves readily enough for the desired pitch; tones of the various degrees of loudness and softness can be sung in a fairly satisfactory manner. But the muscles are somewhat hampered in their contractions, and the response to the demands of the ear is not quite perfect. This lack of perfect command is evidenced specially in the quality of the tones. Some form of throaty quality always mars the voice when the throat is in a stiffened condition. In this regard the voice refuses to fulfill the demands of the ear. Even though the singer hears, and indeed feels, the effects of the muscular tension, and strives to remedy the fault of production, the voice still refuses to respond. This incomplete command of the voice is frequently observed, even among singers of very high standing. At first sight the condition here described seems to disprove the statement that the voice normally obeys the ear. But there is no real contradiction of the psychological law of vocal command in the case of a stiff-throated singer. For one thing, whatever degree of command the singer possesses is obtained in accordance with the law of guidance by the ear. Moreover, the failure to secure perfect response is due solely to the interference with the normal workings of the voice, occasioned by the state of throat stiffness. Far from this form of muscular contraction being a contradiction of psychological principles, it will be found on examination to be in perfect accord with well-established laws of physiological psychology. It is hardly to be supposed that the singer consciously and voluntarily contracts the muscles of the entire vocal mechanism and so deliberately brings about the stiffening of the throat. True, this can readily be done. We can at will sing throaty and nasal tones. But this form of voluntary throat tension is not, properly speaking, an incorrect vocal action. So long as the vocal organs respond to the demands of the ear, the vocal action is correct. Only when the voice refuses to obey can the action be described as incorrect.