SPEECH POWER AND ITS MEASUREMENT 



659 



voltmeter. The curve shows the time rate at which the potential on 

 the blocking condenser builds up. The time required for the galva- 

 nometer to reach its maximum deflection is determined by the dynamic 

 characteristic of the meter and associated plate circuit, as well as by 

 the time constant of the condenser charging circuit. 



6 8 10 12 14 16 18 20 22 



'R- RATIO OF PEAK TO AVERAGE TOTAL PRESSURE - 



24 



DB 



Fig. 13 — Distribution of peak pressures for entire speech spectrum — three male 

 voices — ^each peak is the maximum instantaneous pressure during 1/8 sec. 



In using the volume indicator type of instrument in the telephone 

 plant, limits are observed which have been determined by trial to give 

 satisfactory operating results. The fact that it is possible to set such 

 limits indicates a correlation between mean syllabic power and peak 

 pressures. The overload capacity of apparatus is so important that 



