GENERAL PAPERS 45 



as continuity, vicinal action, analyticity, uniqueness, deter- 

 minability, and others of the same ponderous character, must 

 be left aside, and that discontinuity, distal action, mono- 

 geneity, polydromicity, statisticity, and the like, must become 

 the more frequent. And all these demand mathematical de- 

 velopment which is as yet only dreamed of. 



THE CORRECTION OF ECHOES AND REVERBERA- 

 TION IN THE AUDITORIUM AT THE 

 UNIVERSITY OF ILINOIS 



By F. R. Watson, University of Illinois 



A brief account is given herewith of an investigation of the 

 acoustical defects of the Auditorium at the University of Illi- 

 nois. This investigation has extended over a period of nearly 

 seven years and was recently brought to a conclusion when 

 materials were installed to correct the reverberation and 

 echoes. 1 



The Auditorium is a large structure nearly hemispherical in 

 shape, with several large arches and recesses which break the 

 regularity of its inner surface. Because of its large size and 

 concreted curved walls, it was afflicted with both a reverbera- 

 tion and echoes. A watch ticking on the pulpit could be heard 

 far away in the balcony. A whisper started by an observer 

 on the stage was returned so that it could be heard distinctly 

 after it had traveled a distance of 225 feet. Echoes were 

 heard from every direction and the reverberation lasted for 

 several seconds. Speakers found their utterances thrown back 

 at them and auditors in every part of the house had difficulty 

 in understanding what was said. 



This unfortunate condition proved beneficial in the respect 

 that it allowed tests of faulty acoustics to be made under ex- 

 ceptionally good conditions. A systematic investigation, 

 avoiding "cut-and-dry" methods of cure, was inaugurated first 



'Detailed accounts of the investigation with numerous drawings and photograph- 

 may be obtained in Bulletins Nos. 73 and 87 on "Acoustics_ of _ Auditoriums," and 

 "The Correction of Echoes and Reverberation in the Auditorium, University of 

 Illinois." published hv the Engineering: Experiment Station of the Unirersity of 

 Illinois. These bulletins may be obtained on application to the author or to the 

 Director of the Engineering Experiment Station, Unirersity of Illinois, Urbana, 111. 



