1862.] 145 



valve of the glottis in opening and closing the vocal tube performs 

 an action resembling that of some of the musical reeds. 



The human organs of voice have been considered by a great many 

 distinguished philosophers as constituting a reeded instrument, and 

 the relation in which they stand to instruments of that character 

 has been already discussed in my paper in the * Transactions ' of the 

 Royal Society for the year 1846; it only remains to remark that 

 the phenomena brought to light by means of the laryngoscope tend 

 to confirm the idea that the vocal organs really perform the double 

 eifect both of reed and string. 



In ejaculatory sounds, such as the production of the syllables ha, 

 ha, ha in laughing, the glottis is opened at each intermission and 

 closed at each intonation of sound, thus producing a rapid succession 

 of opening and closing the glottis. 



In a paper published in the * Proceedings of the Royal Society *,' 

 by Manuel Garcia, a great number of observations on the movements 

 of the glottis are described ; many of these have been verified both 

 by Professor Czermak and by myself, and we cannot but be gratified 

 by the advance which has been made in our knowledge of the action 

 of the vocal organs during intonation, and that the speculations and 

 controversies which have existed on some points are, by the applica- 

 tion of the laryngoscope, now brought to a satisfactory conclusion. 



The great differences which we find to exist in the quality of the 

 sounds produced those, for example, of the chest, and those of the 

 falsetto character, the causes of which have excited so much specu- 

 lation are in reality effected by very simple changes in the mecha- 

 nism of the larynx. 



It would have been possible to extend this paper by pursuing 

 the inquiry into the details of the special action of the muscles, 

 and the distribution and functions of the nerves of the larynx, as 

 well as the play of the several cartilages, but I have restricted 

 myself to the actual phenomena presented to the eye, and to the 

 acoustic deductions arising out of the movements of the larynx, more 

 especially those of the thyro-arytenoid ligaments. 



The waves of sound generated by the larynx in the column of air 

 contained in the vocal tube, set the whole of the membranes sur- 

 rounding the tube in a vibratory, reciprocating motion, and we know 

 * May 24, 1855. 



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