Throat stiffness, the characteristic feature of all incorrect vocal actions, is exactly similar in its nature to the stiffness of the hand and arm just considered. The laryngeal muscles are also arranged in sets which oppose their action one to another. One set (the posterior crico-arytenoids) opens the glottis, another set (the arytenoideus and the lateral crico-arytenoids) closes the glottis and brings the vocal cords on tension. Now, if the glottis opening muscles are contracted during tone production, the opposed muscles must put forth enough strength to overcome the effects of this contraction in addition to that which they are normally called upon to exert. This applies also to all the other sets of laryngeal muscles. Through this excessive tension the delicate laryngeal muscles are strained and weakened, and in the course of time the voice is permanently injured. This condition of throat stiffness is by no means uncommon, a matter for which modern methods of voice culture are to a certain degree responsible. The attempt to manage the vocal organs directly is very apt to lead to excessive tension of the muscles. Throat stiffness is very insidious in its workings. It tends always to become more pronounced and to impose a constantly greater strain on the voice. Yet in its beginnings the singer may be completely unaware of any trouble. The muscles of the larynx are very poorly supplied with sensory nerves, so poorly, indeed, that under ordinary circumstances we are utterly unconscious of their movements. Owing to this fact, a condition of strain may exist without making itself manifest by any painful sensation. It thus comes about that a singer may suffer from the constantly progressing effects of throat stiffness before its results are so pronounced as to be painful. Yet there is one infallible way of determining whether a voice is correctly used, or whether, on the contrary, its production is characterized by excessive muscular tension. This is found in the sound of the tones. Any degree of throat stiffness is invariably reflected in the sound of the voice. A throaty quality of tone always results from an incorrect manner of production, and this quality can result in no other way. While a keen and highly experienced ear is needed to detect a slight degree of throatiness, any ordinary observer can hear this condition when it is very pronounced. True, it is very much easier to detect a throaty quality in the voice of some one else than in one’s own voice. The singer labors under this disadvantage, that he can never hear his own voice as clearly and with the same discrimination as can the people who listen to him. Yet by practice and careful attention this difficulty can in great measure be overcome.