122 



BELL SYSTEM TECHNICAL JOURNAL 



produced in a perfect manner. Rough experimental data indicate 

 that the loudness in an orchestra selection may vary from one part 

 of the selection to another by a ratio as great as 50,000 to 1. While 

 the present equipment does not operate with entire satisfaction over 

 this range of loudness, it has been found relatively easy to obtain 

 good results by manual adjustment of the amplification during the 

 rendering of the selection. If the gain is varied in small enough 

 steps, the change is not noticeable to the listeners. 



An increase in the loudness range would render the manual ad- 



¥^X-Z 



Fig- 4. 



justment unnecessary and would make the reproduction a faithful 

 duplicate of the music as actually played . 



Technical Description of the System 



The foregoing discussion having described the requirements which 

 must be met in order that the public address system shall successfully 

 transmit speech and music, the system in its commercial form will 



