SABINE. — AKCHITECTURAL ACOUSTICS. 55 



Room 5 had a carpet, chairs, and shelia curtains. 



Thus the rooms varied from an almost unfurnished to a reasonably 

 furnished condition. In all cases the reverberation was too great. 



The experiment was begun in room 1. There were, at the time, 

 besides the writer, five gentlemen in the room, the absorbing effect of 

 whose clothing, though small, nevertheless should be taken into account 

 in an accurate calculation of the reverberation. Thirteen cushions from 

 the seats in Sanders Theatre, whose absorbing power for sound had been 

 determined in an earlier investigation, were brought into the room. 

 Under these conditions the unanimous opinion was that the room, as 

 tested by the piano, was lifeless. Two cushions were then removed 

 from the room with a perceptible change for the better in the piano 

 music. Three more cushions were removed, and the effect was much 

 better. Two more were then taken out, leaving six cushions in the 

 room, and the result met unanimous approval. It was suggested that 

 two more be removed. This being done the reverberation was found 

 to be too great. The agreement was then reached that the condi- 

 tions produced by the presence of six cushions were the most nearly 

 satisfactory. 



The experiment was then continued in Mr. Dunham's room, num- 

 ber 2. Six gentlemen were present. Seven cushions were brought into 

 the room. The music showed an insufficient reverberation. Two of the 

 cushions were then taken out. The change was regarded as a distinct 

 improvement, and the room was satisfactory. 



In Mr. Whitney's room, number 3, twelve cushions, with which it 

 was thought to overload the room, were found insufficient even with 

 the presence in this case of seven gentleman. Three more cushions 

 were brought in and the result declared satisfactory. 



In the fourth room, five, eight, and ten cushions were tried before the 

 conditions were regarded as satisfactory. 



In Mr. Proctor's room, number 5, it was evident that the ten cush- 

 ions which had been brought into the room had overloaded it. Two 

 were removed, and afterwards three more, leaving only five, before a 

 satisfactory condition was reached. 



This completed the direct experiment with the piano. 



The bringing into a room of any absorbing material, such as these 

 cushions, affects its acoustical properties in several respects, but princi- 

 pally in respect to its reverberation. The prolongation of sound in a 

 room after the cessation of its source, may be regarded either as a case 

 of stored energy which is gradually suffering loss by transmission 

 through and absorption by the walls and contained material, or it may 

 be regarded as a process of rapid reflection from wall to wall with loss 



