364 



BELL SYSTEM TECHNICAL JOURNAL 



It was seen from the oscillographs that the vowels have much greater 

 phonetic powers than the consonants. Studies of these phonetic 

 powers for average conversation have indicated that for a typical 

 speaker they are as shown in Table II. The most powerful sound is 



TABLE II 



the vowel in the word "awl" which carries about 900 times as much 

 power as the weakest sound which is th as in thigh. This most 

 powerful vowel when intoned without emphasis is about 50 micro- 

 watts. The relative position in this table depends upon the emphasis 

 given. An emphasized syllable has about three times as much 

 syllabic power as an average one and as will be seen from the table 

 this is about the range of powers among the different vowels. 



An analysis of a few oscillograms such as we first considered for 

 determining the peak powers was made and showed that the peak 

 powers are from 10-20 times the phonetic power. It is thus seen that 

 when the vowel in the word "awl" is emphasized, the peak power is 

 from 50 to 200 times the average speech power. To find how fre- 

 quently these peak powers occur, the apparatus described above using 

 the glow discharge tube circuits was used. The results obtained are 

 shown in Table III. 



TABLE III 



Per Cent of Number of db the Peak Power 



1/8 Second in the Interval is Above 



Intervals the Average Level 



2 , . above 20 



3 18 to 20 



6 16 to 18 



8 14 to 16 



10 12 to 14 



11 10 to 12 



11 8 to 10 



10 6 to 8 



8 4 to 6 



6 2 to 4 



4 Oto 2 



21 Below the average 



