Can someone please point me in a direction where I could find information about the geometry of anechoic wedges like the original ones developed by Beranek and Sleeper. Unfortunately I don't have access to the original article (Leo Beranek and Harvey P. Sleeper, Jr., "The Design and Construction of Anechoic Sound Chambers," Journal of the Acoustical Society of America 18 (1946): 140-150) but if someone know where to get a PDF, please let me know.
All I've found this:
An anechoic wedge is designed to provide a normal-incidence sound absorption coefficient greater than 0.99 for all frequencies down to its design cutoff frequency. Reflected sound from such a wedge is attenuated 20 dB or more. An anechoic wedge is typically one-quarter wavelength long at its cutoff frequency. For example, a 100 Hz cutoff wedge is usually approximately 36 inches long. The design and production of effective anechoic wedges is an extremely difficult task and is best left to acoustic chamber manufacturers.