60 proceedi:ngs of the American academy. 



reverberation, he added that he found it difficult to avoid pitching 

 his voice to that note which the auditorium most prolongs notwith- 

 standing the fact that he found this the worst pitch on which to speak. 

 This brings out, perhaps more impressively because from practical 

 experience instead of from theoretical considerations, the two truths 

 that auditoriums have very different reverberation for different pitches, 

 and that excessive reverberation is a great hindrance to clearness of 

 enunciation. Another incident may also serve, that of a church near 

 Boston in regard to which the writer has just been consulted. The 

 present pastor, in describing the nature of its acoustical defects, stated 

 that different speakers had different degrees of difficulty in making 

 themselves heard ; that he had no difficulty, having a rather high 

 pitched voice ; but that the candidate before him, with a louder but 

 much lower voice, failed of the appointment because unable to make 

 himself heard. Practical experience of the difference in reverberation 

 with variation of pitch is not unusual, but the above cases are rather 

 striking examples. Corresponding effects are not infrequently ob- 

 served in halls devoted to music. Its observation here, however, is 

 marked in the rather complicated general effect. The full discussion 

 of this belongs to another series of papers, in which will be taken up 

 the subject of the acoustical effects or conditions that are desirable 

 for music and for speech. While this phase of the subject will not 

 be discussed here at length, a little consideration of the data to be 

 presented will show how pronounced these effects may be and how 

 important in the general subject of architectural acoustics. 



In order to show the full significance of this extension of the in- 

 vestigation in regard to reverberation, it is necessary to point out some 

 features which in earlier papers were not especially emphasized. Pri- 

 marily the investigation is concerned with the subject of reverbera- 

 tion, that is to say, with the subject of the continuation of a sound 

 in a room after the source has ceased. The immediate effect of 

 reverberation is that each note, if it be music, each syllable or part 

 of a syllable, if it be speech, continues its sound for some time, and by 

 its prolongation overlaps the succeeding notes or syllables, harmoniously 

 or inharmoniously in music, and in speech always towards confusion. 

 In the case of speech it is inconceivable that this prolongation of the 

 sound, this reverberation, should have any other effect than that of 

 confusion and injury to the clearness of the enunciation. In music, 

 on the other hand, reverberation, unless in excess, has a distinct and 

 positive advantage. 



Perhaps this will be made more clear, or at least more easily realized 

 and appreciated, if we take a concrete example. Given a room com- 



