The Duke University Anechoic Chamber is located in the basement of Hudson Hall in room 029J.
Constructed in 1994 by Willam Clayton, the chamber offers an acoustically isolated testing facility with highly absorptive walls for students and faculty to use. The anechoic ("an-echoic" meaning non-echoing) properties of the chamber allow for direct field measurements, simulating free-space and thus minimizing the reverberant field found in real world environments.
Sound absorption is achieved through the soft foam wedges located along the chamber wall. Incident acoustic waves become trapped within the porous foam structure and converted into small amounts of heat that then dissipate behind a blanket of condensed fiberglass. This process is most effective at higher frequencies where the wavelength is much smaller than the wedge length (3 in.). The lower frequency cutoff limit is roughly determined by the quarter wavelength rule which equates to 1000 Hz.
The chamber at Duke is fully anechoic (absorptive floor) and features a mesh floor grating for supporting equipment. Threaded rods are conveniently mounted onto the ceiling allowing for hanging of sound sources with rotation available through a stepper motor adapter. Electrical outlets are located on all four side walls along with a small window for feeding cables outside the room. The dimensions of the chamber are 9x12.5x7.5 ft high. For more information or to check availability, please contact us at firstname.lastname@example.org.
Beranek, Leo L. and and Harvey P. Sleeper Jr. "The Design and Construction of Anechoic Sound Chambers." The Journal of the Acoustical Society of America 18. 140 (1946).