CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 



HARVARD COLLEGE. 



ARCHITECTURAL ACOUSTICS. 



Presented Dec. 13, 1905. Received March 22, 1906. 



I. Introduction. 



The problem of architectural acoustics requires for its complete 

 solution two distinct lines of investigation, one to determine quan- 

 titatively the physical conditions on which loudness, reverberation, 

 resonance, and the allied phenomena depend, the other to determine 

 the intensity which each of these should have, what conditions are 

 best for the distinct audition of speech, and what effects are best for 

 music in its various forms. One is a purely physical investigation, 

 and its conclusions should be based and should be disputed only on 

 scientific grounds ; the other is a matter of j udgment and taste, and 

 its conclusions are weighty in proportion to the weight and unanimity 

 of the authority in which they find their source. For this reason, these 

 papers are in two series. The articles which appeared six years ago 

 began the first, and the paper immediately following is the beginning 

 of the second. 



Of the first series of papers, which have to do with the purely physi- 

 cal side of the problem, only one paper has as yet been published. This 

 contained a discussion of reverberation, complete as far as one note is 

 concerned. There is on hand considerable material for a paper ex- 

 tending this discussion to cover the whole range of the musical scale, 

 and therefore furnishing a basis for the discussion of what has sometimes 

 been called the musical quality of an auditorium. There has also been 

 collected a certain amount of data in regard to loudness, resonance, 

 interference, echos, irregularities of air currents and temperature, and 

 the transmission of sound through walls and partitions, — all of which 

 will appear as soon as a complete presentation is possible in each case. 

 Each problem has been taken up as it has been brought to the writer's 

 attention by an architect in consultation either over plans or in regard 

 to a completed building. This method is slow, but it has the advan- 

 tage of making the work practical, and may be relied on to prevent 



