310 



TABLE 302A.— SPEECH POWER (Fig. 1) 



In a study conducted by Dunn and White, 101 the "long-time-interval average" power of 

 speech, obtained by averaging data over time intervals of more than a minute of continuous 

 speech, for the average of a group of male speakers was found to be 34 microwatts. The 

 corresponding value for female speakers was 18 microwatts. At least 1 percent of the 

 g-second intervals had an average power in excess of 230 microwatts for men and 150 

 microwatts for women, and a peak power in excess of 3600 microwatts for men and 1800 

 microwatts for women. The figure shows how the total power of average conversational 

 speech is distributed with respect to frequency. These data give the power per cycles 

 versus frequency and also the percentage power lying below a given frequency. 



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FREQUENCY IN CYCLES PER SECOND 



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Fig. 1. — Speech power for men (continuous curves) and women (dotted curves) given 

 in percentage power below any frequency. Curves A and B, power per cycle, curves C and 

 D, O db = 1 microwatt. 



101 Dunn, H. K., and White, S. D., Journ. Accoust. Soc. Amer., vol. 11, p. 278, 1940. 



TABLE 303.— PEAK POWER OF MUSICAL INSTRUMENTS 



Watts 

 Orchestra, 



75 pieces 70 



Bass drum, large.. 25 



Pipe organ 13 



Snare drum 12 



Watts 



Cymbals 10 



Trombone 6 



Piano 3 



Trumpet 3 



Bass viol 2 



Watts 



Piccolo 08 



Flute 06 



Clarinet 05 



French horn 05 



Triangle 05 



102 Sivian, L. J., Dunn, H. K., and White, S. D., Journ. Acoust. Soc. Amer., vol. 2, p. 330, 1931. 



SMITHSONIAN PHYSICAL TABLES 



