932 OP THE VOICE AND SPEECH. 



in this manner the note of a membranous reed may be raised by semitones, to 

 as much as a fifth above the fundamental. The addition of a pipe has nearly 

 the same effect on their pitch as on that of metallic reeds ; but it cannot easily 

 be determined with the same precision. The effect of the junction of a pipe 

 with a double membranous tongue is well shown in the Trumpet, Horn, and 

 other instruments, which require the vibration of the lips, as well as a blast 

 of air, for the production of their sound, having no reed of their own. By 

 some, these instruments have been classed with Flute-pipes; but the conditions 

 of their action are entirely different. The mouth-piece of the horn or trumpet 

 is incapable of yielding any tone, when a current of air is merely blown through 

 it ; and the lips are necessary to convert it into a musical reed, being rendered 

 tense by the contraction of their sphincter, partly antagonized by the slightly 

 dilating action of other muscles. The variation of the tension of the lips is 

 effected by muscular effort ; and several different notes may be produced with a 

 pipe of the same length; but there is a certain length of the column of air 

 which is the one best adapted for each tone; and different instruments possess 

 various contrivances for changing this. It has been recently ascertained that 

 the length of the pipe prefixed to the reed has also a considerable influence on 

 its tone, rendering it deeper in proportion as it is prolonged, down to nearly the 

 octave of the fundamental note; but the pitch then suddenly rises again, as in 

 the case of the tube placed beyond the reed. The researches of Miiller, how- 

 ever, have not succeeded in establishing any very definite relation between the 

 lengths of the two tubes, in regard to their influence on the pitch of the reed 

 placed between them. 



934. From the foregoing statements, it appears that the true theory of the 

 Voice may now be considered as well established, in regard to this essential 

 particular that the sound is the result of the vibrations of the vocal ligaments, 

 which take place according to the same laws with those of metallic or other 

 elastic tongues : and that the pitch of the notes is chiefly governed by the ten- 

 sion of these laminae. 1 With respect, however, to the mode and degree in 

 which these tones are modified by the shape of the air-passages, both above and 

 below the larynx, by the force of the blast, and by other concurrent circum- 

 stances, little is certainly known; but no doubt can be felt that these modifica- 

 tions are of great importance, when we observe the great amount of muscular 

 action which takes place consentaneously with the production of vocal tones, 

 and which seems designed to modify the length and tension of the various parts 

 of the Vocal Tube, so that they may vibrate synchronously with the Vocal Cords. 

 Thus, during the ascent of the voice from the deeper to the higher notes of the 

 scale, we find the whole larynx undergoing an elevation towards the base of the 

 cranium, the thyroid cartilage being drawn up within the os hyoides, so as even 

 to press on the epiglottis; at the same time, the small space between the thyroid 

 and cricoid cartilages, or crico-thyroid chink, is closed by the depression of the 

 front of the former upon the latter ( 928); the velum palati is depressed and 

 curved forwards; and the tonsils approach one another. The reverse of all 



1 It is considered, however, by Mr. Bishop ("Cyclop, of Anat. and Physiol.," vol. iv. 

 p. 1486), that the vocal apparatus combines the properties of a stretched cord, a mem- 

 branous pipe with a column of air vibrating in it, and a reed ; and is the perfect type, of 

 which these instruments are only imperfect adaptations. The Author is unable, how- 

 ever, to deduce from Mr. Bishop's previous statements the grounds upon which he makes 

 this assertion; and does not understand how any instrument can combine the actions of 

 strings and of tongues, the laws of whose vibration are so different. That the column of 

 air in the air-passages is thrown into vibration consentaneously with the production of 

 sound by the vocal cords, and intensifies that sound by reciprocation, can scarcely be 

 doubted; but the reasons previously given appear to the Author sufficient to disprove the 

 notion, that this vibration is at all more essential to the production of the vocal tone than 

 it is in the reed-pipe of an organ. 



