THEORY OF VIBRATION OF THE LARYNX 



221 



Its occurrence here is the simplest possible for when there are appre- 

 ciable concealed or ignored modes of motion it may have the form 

 of a generalized impedance containing at least one element of resist- 

 ance, but will always be non-symmetrical as a whole in sign in the 

 determinant. 



The use of the circuit for representing the mechanical system is an 

 extension of an old but recently popularized method of studying 

 mechanical or electrical vibrating systems by the help of analogy, 

 one with the other. The extension consists in the explicit representa- 

 tion by diagram of the gyrostatic mutual which makes the deter- 

 minant unsymmetrical in sign and of the unilateral mutual which 

 makes the determinant unsymmetrical in magnitude. Fig. 6 is a 



K. 



■m^5^ 



AAAAA 



^m^ 



AAAAA- 



Fig. 6 — General Wind Reed Circuit. 



diagrammatic representation of the more general system of deter- 

 minant (30). This includes the external Yq reactions as well as the 

 internal. 



Having thus described the extended method of analogy the follow- 

 ing study of the larynx with the help of the circuit diagram of its 

 determinant should be clear. 



Sustained Vibration of the Simple Larynx 



In vibrating, the vocal cords do not receive excitation of the fre- 

 quency at which they vibrate. The source of power is in the air 

 stream /i which enters the equations in iv",,, the unilateral mutual 

 impedance. Since this is treated as a constant circuit or dynamical 

 element this air stream may be ignored as a drive and the resulting 

 15 



