Fogg Art Museum Lecture Room :
A calibrated recreation of the birthplace of Room Acoustics

This page provides a link to the paper, presentation, and model files for the study presented in Budapest at the Forum Acusticum 2005.
Session  : RBA-HB Reconstruction of historic buildings by using auralisation techniques
Paper ID : 608-0

Authors :

            Brian FG Katz, Perception Située, LIMSI-CNRS, BP 133, F91403 Orsay, France

www.limsi.fr/Recherche/PERSI/

katz@limsi.fr

Ewart A. Wetherill, AIA, 28 Cove Road, Alameda, California 94502, USA

redwetherill@sbcglobal.net

 

This study was an attempt to recreate the Fogg Art Museum Lecture Room in which Sabine first started his work in Room Acoustics. This room, which was demolished in 1973, underwent a series of renovations. The goal was to create a series of model and, working backwards, arrive at the original state of the room in which Sabine found it.  

In the aim of sharing the results of this work, the GEO files for the room model are made publicly available here to the academic and research community. We ask only that the model source be referenced in the event that any publications are produced. The model is provided “as is.” The model is based on over 30 years of documentation research in order to determine the many details of the room geometry and material definitions. While the work has been extensive, it is not final. Even in the weeks preceding the conference date, new details were realized in an early publication by Sabine on the nature of the absorption material which he installed to correct the room’s acoustics.

Paper abstract:

At the end of the 19th century, an assistant professor of physics at Harvard University named Wallace Clement Sabine undertook the task of correcting the acoustics of the Fogg Art Museum Lecture Hall. Rather than merely correcting the acoustics, Sabine’s work on this acoustically difficult space (semi-circular, domed, with arched perimeter) formed the basis for his monumental research on reverberation time and absorption. This work and its subsequent publication established Room Acoustics as a real science, rather than guesswork and luck. During the next 70 years the room underwent several large renovations, and was demolished to make space for student housing in 1973. Learning of the impending demolition, one of the authors was fortunately able to access the room, making several room impulse response measurements the day prior to its final destruction. A computational room acoustics model has been created using architectural plans and the few available photographs. The historically important impulse response measurements of the room provide a reference calibration for the model. The geometrical model includes the various architectural phases of the room during its lifetime. Through simulation and auralization these versions of the room are restored in acoustical terms, allowing one to “experience” an educated rendering of the original acoustics as Sabine found it in 1895. The results of this study, in particular the geometrical model, will be made available for public use, to allow future room acoustics students and researchers the opportunity to aurally follow in Sabine’s footsteps.

The paper: FA2005KatzWetherill.pdf

The presentation: FA2005KatzWetherill_Slides.pdf (includes links to auralization walkthrough files)

The room geometry:             FoggArtMuseum.OGL (CATT OpenGL)
                                               FoggArtMuseum1898.wrl.zip (VRML room model, ZIPPED)

Two room geometries are defined in the given model. The original room geometry (1895)

and the smaller room, after the renovation in 1911.

The room model: CATTgeoArchivePublic.zip (GEO files and SabineFoggArtMuseum.PRD setup file)

The model was created using CATT-Acoustics version 8.0d. It makes full use of MIRROR, LOOP, plane loop, IF THEN, SAY, and mathematical functions in the current version of CATT. The GEO model structure contains over a dozen sub-files as the room has been constructed in 3 major sections: the podium, the dome, and the lower seating area. Using the rotational symmetry of the dome and seating areas the actual number of geometry definitions has been limited. While rotation symmetry can be used easily for interior planes such as reflectors, the use of COPY for the external envelope creates issues in creating a closed volume. For this reason, the GEO uses sub-files which are used to stitch together the various elements. The use of these files can be controlled using simple IF THEN switches within the GEO files.

Two MASTER files are used (MASTER189x.geo & MASTER1912.geo) for controlling the different geometry sub-file inclusions.

A single GEO file has been used for all material property definitions (ABSdefs.geo). A single GLOBAL variable must be defined in the MASTER file to select the current absorption definitions. This allows for flexible material definitions to account for the various renovations and modeling states (including semi-occupied and occupied conditions). The definitions in this file differ slightly from those used in the paper/presentation and correspond to revised information found concerning Sabine’s acoustic treatment.

In addition, the height of the audience_box can be varied through a single variable for both models, allowing for an un-occupied empty condition, such as was used for various measurements made in the room.

Finally, the GEO files include comment lines in the hopes of easing their use, as well as SAY commands to verify the absorption condition used, and a verbose condition which states each sub-file being INCLUDEd.

LIMSI : Perception Située Research group : www.limsi.fr/Recherche/PERSI/

06-sept-05