106 



BELL SYSTEM TECHNICAL JOURNAL 



TABLE I 



Natural or Characteristic Frequencies of the Vowel Sounds 

 {Male Voices) 



* Poorly resolved, in our charts. 



t In Paget's notation, for the sound as in not. 



% Considering er to have triple resonance. 



The main resonances of most of these sounds are so pronounced that 

 it is not at all difficult to take the correct data from the original charts, 

 gnoring the less-essential minor peaks. In only one case (a as in talk) 

 does our original chart fail to resolve the two principal peaks, but they 

 are partially resolved even in this case, so that there is no great un- 

 certainty in the figure given. In the case of the sound er, a third 

 frequency is shown in the diagram. Reasons will be given later for 

 considering this sound to be produced by a system of three degrees of 

 freedom. 



Mechanism of the Double Resonator System 



There are two ways of studying the action of the double resonator 

 at its resonant frequencies. If we drive the back of the inner chamber 

 with a source of prescribed motion, then the greatest motion in the 

 orifices will be obtained when the driving point impedance of the 

 system as viewed from the hack of the inner chamber is infinite. Or, 

 equally, if we drive the system (by sound waves, say) from the front 

 orifice, then the greatest motion will be obtained for those frequencies 

 for which the driving point impedance of the system as viewed from 

 without is zero. By either method we should be able to deduce the 

 natural frequencies of the system; the second method is chosen here 

 because it involves less labor. 



