Page 17 - Summer 2007

Fig. 7. Reverberation Time comparison for 1972.
Fig. 8. STI Comparison: 1895 and 1898.
hall and its strong lack of homogeneity.
As the goal of this study has been to acoustically explore
this historic building, through simulation and auralization, the authors have chosen to make the model files available for edu- cational and academic use. The authors thank Harvard University, Boston Public Library, and Leo Beranek for contin- ued support and Bengt-Inge Dalenbäck of CATT for making the model accessible to the general public (available at www.catt.se/FoggArtMusum.htm). All computer models and
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1 B. F. G. Katz and E. A. Wetherill. “Fogg Art Museum Lecture Room, A calibrated recreation of the birthplace of Room Acoustics.” Proceedings Forum Acusticum, Budapest, 29 August–2 September 2005.
2 B. F. G. Katz and E. A. Wetherill, “Fogg Art Museum lecture room: A calibrated recreation of the birthplace of room acoustics,” J. Acoust. Soc. Am., 120(5), 3009(A) (2006).
3 K. A. Orcutt, Personal Collecting Meets Institutional Vision: The Origin of Harvard’s Fogg Art Museum (Oxford University Press, Oxford, 2006).
4 Annual report to the Board of Overseers of Harvard University, 1900–1902.
5 Boston Daily Advertiser, 18 March 1896.
6 Newspaper article, HUB ref. 1401.2 No date or title of publica-
tion (possibly student newspaper).
7 W. C. Sabine, “Architectural Acoustics: Correction of Acoustical
Difficulties”. The Architectural Quarterly of Harvard University,
March 1912. Reprinted in reference 11.
8 W. C. Sabine, “Architectural Acoustics,” The American Architect
and Building News 62, November 26, 1898. Summarized in ref-
erence 11.
9 W. D. Orcutt, Wallace Clement Sabine (Plimpton, Norwood,
MA, 1933).
10 L. L. Beranek, “The notebooks of Wallace Clement Sabine,” J.
Acoust. Soc. Am. 61(3) 629-639 (1977).
11 W. C. Sabine, Collected Papers on Acoustics (Peninsula
simulations were performed using CATT-Acoustic v.8.0c. The authors also thank Kurt Graffy and Larry Tedford for their assistance and particularly for introducing the authors with the purpose of realizing this study. Sabine’s Collected Papers on Acoustics is available from the Acoustical Society of America and from Peninsula Publishing, Los Altos, California.AT
References for further reading:
Publishing, Los Altos, CA, 1992).
Comparison with Sabine’s data
The fundamental room acoustic parameter is Sabine’s reverberation time. Predicted RT values for the models are given in Table 2. These can be compared to Sabine’s pure-tone measurement of 5.61 sec at 512 Hz for the 1895 state, repre- senting a difference of only 4%, which is within the tolerance
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with 1500 cushions placed throughout the room.
Intelligibility measures
A parameter of great interest in the context of this room and its use is that of intelligibility. This was cited as the major fault of the room, and the reason for Sabine’s involvement. A comparison of the intelligibility before and after Sabine’s intervention is presented in Fig. 8. The lack of homogeneity as mentioned by the accounts is clear. While Sabine’s treat- ment seems to have improved the intelligibility near the cen- ter of the room (particularly at the rear), there still remained a section of seating (dome radial angle region 20°-40°) with a consistently BAD/POOR intelligibility rating. In general, the room would still be classified as having POOR intelligibility.
Summary
This study presents the documentary work, as well as the acoustical modeling method, adopted in an attempt to acoustically reconstruct the Fogg Art Museum Lecture room. Using measured data and related published data by Sabine, a calibrated prediction and simulation model has been created. Comparisons of acoustical parameters and impulse responses indicate a valid model. Initial analysis of intelligibility through predictions appears to corroborate the anecdotal evidence for the poor acoustic functioning of the
There is also a clear reduction in reverberation time following Sabine’s treatment. But, one must note that it does not approach the low values obtained during his scientific study using cushions where he obtained 2.03 sec with all seats covered, and a notable 1.14 sec
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for perceptual and measurement errors.
Table 2. Predicted reverberation time: 1895 & 1898.
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