CARRIER NATURE OF SPEECH 



497 



can be produced from almost any sound stream.' The need of an 

 audible "carrier" to transmit this inaudible "message" is obvious. 



The final example, to illustrate the modulating mechanism in speech 

 production, is from a person talking in a normal fashion. In this 

 example are present the message and carrier waves of the previous 



r /////// 



CARRIER 

 CORD TONE OF VOICED SOUNDS 

 BREATH TONE OF WHISPER 



STEADY 



AIR 

 SUPPLY 



Fig. 1 — The vocal system as a carrier circuit. 



examples, for both are needed if the former is to modulate the latter. 

 However, the mere presence of the carrier and message waves will not 

 make speech for if they are supplied separately, one by a silent talker and 

 the other by an intoner, no speech is heard but only the audible intoned 



^ R. R. Riesz, "Description and Demonstration of an Artificial Larynx," Jour. 

 Acous. Soc. Amer., Vol. 1, p. 273 (1930); F. A. Firestone, "An Artificial Larynx for 

 Speaking and Choral Singing by One Person," Jour. Acous. Soc. Amer., Vol. 11, 

 p. 357 (1940). 



