July 26, 1901.] 



SCIENCE. 



151 



thus shorten the vibrating portion of the cord ; 

 at the same time certain fibers from this muscle 

 extend outward into the cord toward s, t, u, 

 etc. The action of these fibers, when the vocal 

 muscle is contracted, tends to hold rigid more 

 and more of the cord, allowing less and less of 

 the extreme edge to vibrate. This action less- 

 ens the weight of the vibrating part of the cord. 



Other minor facts tend to confirm the belief 

 that the action is essentially that of a cord. 

 For example, the extreme edge, as indicated 

 at h, is of a different material from the rest of 

 the cord and the whole structure of the cord is 

 entirely different from that of the lips, or from 

 what could be properly defined as a cushion. 

 In observations upon the vocal cords when 

 producing a tone it is very often easy to recog- 

 nize certain secondary nodal points in the cord. 

 If a little mucus happens to be upon the vocal 

 cord at the time of producing a continued tone, 

 the mucus collects at the secondary nodal 

 points, just as sand upon a vil»rating plate, and 

 is easily apparent as a white spot upon the edge 

 of the cord. 



Of course, in those cases where the larynx 

 has been removed and an artificial voice ap- 

 paratus has been introduced, the source 

 of sound has been a reed, but this has been 

 simply from a mechanical difficulty of intro- 

 ducing a vibrating string which should have 

 the proper range. The I'eed is extremely sim- 

 ple mechanically and answers the purpose 

 quite satisfactorily. But this offers no argu- 

 ment in support of the belief that we are deal- 

 ing with a reed instrument in the human voice. 

 It is true that Helmholtz and others have 

 referred to the larynx as a reed instrument, 

 but it is curious to note that after this ref- 

 erence has been made, Helmholtz continues 

 in the most elaborate way to treat the quality 

 of the sound produced by the human voice as 

 if it had been produced by a vibrating string, 

 discussing the pitches and intensities of the 

 over-tones of a string and never referring to 

 other over-tones of a reed or a membrane. 



It is claimed that the vibrations of the air in 

 the mouth cavity are ' free vibrations ' and not 

 ' forced ' ones and that these free vibrations in 

 the mouth cavity are excited by the impulses 

 from the larynx formed by the explosive open- 



ings between the vocal cords. In this connection 

 Professor Scripture, in his contribution from 

 the Yale Psychological Laboratory, describes an 

 experiment of making a key whistle by blowing 

 in its end a stream of air, which has been ren- 

 dered intermittent by artificial vocal cords. No 

 one denies for a moment that impulses or a suc- 

 cession of impulses may set up the natural 

 vibrations of a resonance cavity, but it must 

 also be borne in mind that a continuous stream 

 of air under the same circumstances will pro- 

 duce a more forcible result just in proportion 

 as the energy in the continuous stream is 

 greater than in the interrupted stream. Thus, 

 we know that a continuous current will cause 

 a key to whistle, and there is no mechanical 

 reason why an interrupted current should not 

 produce a similar result while the puffs last. 

 Applying this to the mouth cavity as related to 

 speech, we have a natural vibration set up in 

 the case of a whisper by the continuous cur- 

 rent of air rushing through these cavities. In- 

 terruptions in this current will not increase the 

 intensity of the natural vibrations of the air in 

 the cavities. We have precisely an analogous 

 case if we simply blow through a clarionet or 

 cornet or flute without establishing the iDrimal 

 source of sound by the vibration of the reed, 

 the lip, or the air jet. 



It seems to me that, fundamentally, there 

 can be no difference between a vowel as sung 

 and that same vowel as spoken. Of course, 

 the duration of the vowel sound may be very 

 short, but during that period it must have 

 its perfectly definite quality in order to be 

 recognized, and it seems incorrect to assume 

 one set of determining factors in case of 

 a spoken vowel and another set in the case 

 of the vowel as sung. The problems involved 

 in this discussion, overlapping the subjects 

 of anatomy, physiology and mechanics, are 

 naturally very troublesome, and it is readily 

 to be expected that the physicist is perhaps 

 inclined to lay too much stress upon the me- 

 chanics of air vibrations. But on the other 

 hand, the physiologist and the students of 

 phonetics have in too many cases brushed 

 aside serious mechanical obstacles with a non- 

 chalance that is scarcely justified by the facts. 

 In those cases where the synthesis of the vowel 



