Acoustical Plenum Chambers

Sound-treated plenum chambers have been successfully used for sound control of the exhaust gases of jet engines. Probably the earliest reference is Dr. Hardy's paper [“Design characteristics for noise control of jet engine test cells,” J. Acoust. Soc. Am. 24, 185 (1952)]. Such chambers also may be employed to reduce ventilation system noise, etc. This paper presents measured data of a series of tests showing the effect of plenum geometry and absorption. The interaction of adjacent plenums is also considered. Several methods for an approximate calculation of plenum attenuation are examined and correlated with experimental data.