Sound Absorption Coefficients of Acoustical Materials Backed by Large Depth Air Spaces

The Johns‐Manville reverberation chamber technique uses a sample area 8 by 8 ft. A deep pit, beneath the sample, fillable with water to the height desired, provides a ready means for investigating any air space up to 46 in. in depth. Below 600 cps strong depth dependencies were found. The results on a variety of materials are presented.