296 OF THE VOICE AND SPEECH. 



method. It is by the sensibility of the muscles that we become conscious of 

 the existence and direction of motion, to which the whole body is being pas- 

 sively subjected. When sitting upright in a carriage, which is suddenly 

 drawn forwards, we are thrown in the contrary direction ; and it is only by 

 a certain muscular effort that we can regain our position. After some little 

 time, however, we become so habituated to the sensation which this occasions, 

 that we are unconscious of it, except by a certain degree of fatigue which 

 results if it be greatly prolonged. But, when the motion suddenly ceases, we 

 are thrown forwards, showing that the effort itself- had continued ; and not 

 unfrequently the feeling motion is then experienced for a few seconds, as if 

 the sensation remained, and were more perceptible when the cause of it had 

 ceased. 



CHAPTER VI. 



OF THE VOICE AND SPEECH. 



I. The Larynx, and its Actions. 



401. The sounds produced by the organ of Voice constitute the most 

 important means of communication 'between Man and his fellows ; and the 

 power of speech has, therefore, a primary influence, as well on his physical 

 condition, as on the development of his mental faculties. Hence, although it 

 only depends on one particular application of muscular force, comparable to 

 that by which other volitional or emotional movements are effected, it seems 

 right in treating of the Physiology of Man, to make it an object of special 

 consideration. In order to understand the nature of the Organ of Voice as a 

 generator of Sound, it is requisite to inquire, in the first instance, into the 

 sources from which sounds at all corresponding to the human voice are else- 

 where obtained. It is necessary to bear in mind that Vocal Sounds and 

 Speech, or Articulate Language, are two things entirely different ; and that the 

 former may be produced in great" perfection where there is no capability for 

 the latter. Hence we should at once infer that the instrument for the pro- 

 duction of Vocal Sounds was distinct from that by which these sounds are 

 modified into articulat espeech ; and this we easily discover to be the case, 

 the Voice being unquestionably produced in the Larynx whilst the modifica- 

 tions of it, by which language is formed, are effected for the most part in the 

 Oral cavity. The structure and functions of the former, then, first claim our 

 attention. 



402. It will be remembered that the Windpipe is surmounted by a stout 

 bony annulus, termed the Cricoid cartilage, which serves as a foundation for 

 the superjacent mechanism. This is embraced (as it were) by the Thyroid, 

 which is articulated to its sides by its lower horns, round the extremities of 

 which it may be regarded as turning, as on a pivot. In this manner the lower 

 front border of the thyroid cartilage, which is ordinarily separated by small 

 intervals from the upper margin of the thyroid, may be made to approach it or 

 recede from it ; as any one may easily ascertain, by placing his finger against 

 the little depression which may be readily felt externally, and observing its 



