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BELL SYSTEM TECHNICAL JOURNAL 



Relative Power of Vowels 



One test which was made on the speakers was for them to utter dis- 

 connectedly and without accent eleven monosyllables, each of which 

 contained a fundamental vowel sound. The results of this test give a 

 general indication of the inherent power, Pm, in unaccented (but un- 

 slighted) vowels relative to each other. The difference between the 



Fig. 3 — Inherent relative power 



Indicates Male Voices 



Indicates Female N'oices 



Numbers indicate approximate power from voice (in microwatts) 



male and female voices in this respect warrants separate charting of 

 these characteristics. Fig. 3 shows the chart in which the vowels are 

 arranged in the sequence^) the first half of which accompanies an 

 increase in the angle of the speaker's jaws, and the succeeding half 

 accompanies an increase in the elevation of the tongue. 



It might have been anticipated that the more open vowels have 

 more power; but there is apparantly one irregularity in this tendency 

 in the case of the vowel o (as in ton). Furthermore, the vowel e (as 

 in teem) looks somewhat different for the two voices, when compared 

 with the vowels immediately preceding it in the series. There is some 

 difficulty in uttering it so as to make it carry, in the case of female 

 voices — a fact which I have previously encountered when recording 

 them. The male voice, on the other hand, shows a decided rise in this 

 direction. The advantage in the case of u (tool) is reversed: here the 

 male voice begins to fall off while the female voice stays about the 

 same. These results suggest a difference in the resonant structure 



* This arrangement is based upon the well known vowel triangle of Vietor. 



