Stone Y — On Modes of Dealing with Echoes in Rooms. 55 



room without altering it, or are at liberty to prepare the room 

 specially. 



In the first case, it is obvious that by placing the speaker in one 

 corner of the room, we eliminate the direct echo of the two walls 

 which meet at that corner. This is already a great gain, especially 

 if one of the other walls of the room is broken into ^spaces by win- 

 dows. In that event there will remain little direct echo except 

 from the ceiling, and the farther end wall : meaning by direct echo 

 the sound which has only once been reflected. By this simple 

 contrivance it has been found that if the speaker takes proper care 

 with his enunciation, all the audience can be made to hear suffi- 

 ciently distinctly, except those occupying a few definite situations, 

 which can be easily ascertained by experiment, and might with 

 advantage be left without seats. 



Still further mitigation may be effected by placing the speaker 

 in that corner of the room where the two worst, that is, the most 

 uninterrupted, walls meet, and by bringing a canopy of sufficient . 

 size as close over his head as convenient. In the experiments which 

 have been made this canopy was made of cotton cloth stretched on 

 a horizontal frame six feet square, and was brought within a few 

 inches of the head of the speaker. It should be of larger size if 

 placed farther from him, and will be sufficient for* our purpose if 

 it prevents his seeing either the ceiling or the upper parts of tho 

 walls opposite to him. The anticipated effect is as follows : — Distin- 

 guishing the sound of the speaker's voice into the fundamental 

 note on which he speaks and the overtones which give articulate- 

 ness to the sound, it was expected that the overtones, consisting of 

 waves so short that they cannot readily bend round obstacles, would 

 reach the audience with nearly the' full force given to them by the 

 speaker, and that but little of this constituent of the sound would 

 bend enough to reach the ceiling and the walls. On the other 

 hand,, the fundamental note would more readily spread upwards, 

 and would, therefore, produce some, although a reduced, echo. This 

 slight. echo along with the part of the. fundamental note received 

 directly from the speaker's mouth, ought apparently to be heard 

 as a fundamental note of the proper strength to be rendered arti- 

 culate "by the overtones received directly from the speaker, and 

 therefore received by the ear at the proper times to make the 

 utterance distinct. In the experiments which have been made it 



