NATURE OF lANGUAQE — JONES 



503 



ceiving end. The abscissas represent the marginal or cut-off fre- 

 quency of the filter. Looking at the curve for the low-pass filter, 

 marked "Articulation L," the point (1000,40) indicates that an articu- 

 lation of 40 per cent is obtained when the system transmits only fre- 

 quencies up to 1,000 cycles. Looking at the curve for the high-pass 

 filters, marked "Articulation H," the point (1000,86) indicates an 

 articulation of 86 per cent for a system transmitting only fre- 

 quencies above 1,000 cycles. The dotted curves show the per cent 

 of the total energy in speech transmitted through filters of the two 

 types having cut-off frequencies corresponding to the abscissas. 

 Sixty per cent is lost if all the energy below 500 cycles is eliminated, 

 but only 2 per cent of the articulation. The suppression of the 



Effect upon the Articulation and the Energy of Speech 

 of Eliminating Certain Frequency Regions 



1000 



mo 3000 



Frequency 



4000 



FiQ. 8. — Articulation — Distortion characteristics for speech 



frequencies above 1,500 cycles reduces the articulation by 35 per 

 cent but only 10 per cent of the energy lies in this region. The sup- 

 pression of all frequencies below 1,000 cycles has no greater effect 

 than the suppression of the frequencies above 3,000 cycles. This 

 is quite contrary to the popular notion of the characteristics of 

 speech. The mean frequency from the standpoint of articulation 

 is about 1,550 cycles. An articulation of 65 per cent is obtained 

 when either the frequencies below or those above that point are 

 used. The speech quality sounds very different in the two cases, 

 however, in the one being low and dull, and in the other high and 

 shrill. 



It should be borne in mind that naturalness of reproduction, as 

 well as articulation, is an important element of understandable and 



