WAVE ANALYSIS IN REFERENCE TO VOCAL ACTION. Ill 



was, can be seen from the statement of Helmholtz that, when the edges 

 strike together, the sound must be sharp as from striking musical reeds.* 

 The stroboscopic observations of Rethi, however, show that in the male 

 glottis the edges usually strike. Krause reports the case of a tenor whose 

 glottal Hps looked like two ridges of red flesh and whose tones appeared 

 nevertheless unusually sweet and soft. Imhoferf observed a singer with 

 hypertrophy of one of the ventricular bands so that the glottal lip appeared 

 as only a small edge beneath the heavy mass of the ventricular band resting 

 upon it; with this apparently unavailable organ he is a successful tenor 

 on one of the largest German stages. Both these cases can be understood 

 on the puff theory, according to which the glottal lips in most cases come 

 together at each vibration and open only to emit the puff of air. This 

 theory will now be discussed. 



According to the "puff theory" of WiUis and Hermann the glottis 

 emits a series of more or less sharp puffs; each puff, striking a vocal 

 cavity, produces a vibration whose period is that of the cavity; a single 

 wave-group shows the sum of these vibrations from all the cavities; the 

 periods of these vibrations may stand in any relation to the interval at 

 which the puffs come, that is, to the fundamental. 



This theory is certainly correct in asserting that the glottal tone (the 

 fundamental) consists of a series of more or less sharp puffs. Many of 

 the vowel curves (see [a] and [a] in the Depew and Cock Robin plates) 

 show groups of vibrations of which the first is sUghtly larger, as if it 

 had resulted from a sudden impulse. The vowel curves can be counter- 

 feited by apparatus built to apply sharp puffs to damped springs; some 

 experiments in this direction will be described in Chapter X below. The 

 puff action of the vocal Ups has, moreover, been directly observed for 

 male bass voices by the laryngo-stroboscope. 



The more sudden the puffs the more unUke they are to a simple sinu- 

 soid and the more completely they will fail to appear as a fundamental 

 in a simple harmonic analysis. The relation between the amphtude of 

 the chief cavity tone and that of the fundamental indicated by a simple 

 harmonic analysis can be used directly as an index of the sharpness of 

 the puffs; a weak first harmonic with a strong higher one indicates a 

 strong sharp puff; a strong first harmonic indicates either a smooth puff 

 or the presence of a cavity tone of the same period as the puffs. 



As shown by the hundreds of analyses made by Hermann and my- 

 self, the theory is also correct in asserting that the pitch of a cavity tone 

 is to a great extent independent of the interval of the puffs. A sharp 

 puff acting on a cavity will arouse a vibration whose period is that natural 



♦Helmholtz, Lehre v. d. Tonerapfindungen, 5. Aufl., 169, Leipzig, 1896. 

 I Irohifer, Die Kraakb^iten dar Singstimme, 25, Berlin, 1904. 



