298 ILLINOIS STATE ACADEMY OF SCIENCE 



longed. The walls were to be quite reflecting, with venti- 

 lators at critical positions to avoid echoes and undue rever- 

 beration. The absorbing material was located largely in 

 the seats which were to have considerable upholstery. The 

 results obtained are in accordance with the predictions. 

 One performer stated: *'It is easy to sing in the Hall — 

 the notes flow freely and the voice can be used almost with- 

 out effort." Instrumental music — that is, chamber music 

 of moderate intensity — is also rendered so as to produce a 

 pleasing effect. A maximum audience reduces the rever- 

 beration somewhat without detriment to the acoustics. 

 The room is not suited for heavy music of great intensity, 

 since this would be rather overpowering. Neither is it 

 well suited for speaking because of the relatively long 

 period of reverberation. 



The other auditorium to be described is located in the 

 Wesley Foundation Social Building. This room was to be 

 used primarily for speaking; therefore, the acoustical de- 

 sign was quite different from the Concert Room of the 

 Music Building. The period of reverberation should be 

 short in order that a spoken word after making its impres- 

 sion should die out quickly. As in the preceding case, here 

 too, the theory of the subject with illustrative halls gave 

 suitable guidance for the acoustical prescription. It was 

 recommended that the ceiling walls of the room, which 

 formed an inverted V, should be covered with a sound ab- 

 sorber — a pulp board in this case — that could be easily in- 

 stalled and which presented an acceptable appearance. 

 Calculations showed that this material would give a rever- 

 beration acceptable for speaking for a room with the 

 volume of the Wesley Auditorium. The outcome confirms 

 the prediction. Speaking is heard distinctly even when 

 only several people are present. With a maximum audi- 

 ence of about 700 people, the conditions are improved. One 

 rather surprising feature in the acoustics is the satisfac- 

 tory rendering of vocal music. This was not anticipated, 

 but it would seem that a room acceptable for speaking is 

 also suited for vocal music. Instrumental music, such as 

 that of a piano, is heard at a disadvantage. For this, the 

 room is too "dead." 



