176 BELL SYSTEM TECHNICAL JOURNAL 



type have in the past not led to any useful results because of the large 

 variations in acoustic pressures produced by standing waves. When 

 a high-speed level recorder is used to record pressure levels automati- 

 cally as the frequency of a constant source is continuously varied, 

 curves are obtained which not only show the variations in the general 

 level of acoustic pressures in the various frequency regions, but which 

 also permit an evaluation of the reverberation characteristics of 

 different parts of the room. The paper shows curves obtained with 

 the recorder under various room conditions. 



