Downloaded from https://www.everyspec.com MIL-STD-81OC TABLE 515.2-1 Acoustical Noise Test Category Test overall ;“oundpressure Typical applications Exposure Category level (d~) time J Vehicle Equipment location (minutes) Aircraft Majority of locations 30 Near the noise source or A Aircrafl w Aircraft B 150 : c 160 I any aircraft I Majority of locations, Rocket exclusive of booster or 8 D 165 B ~/Reference 2x1O‘4 dynes/cm2 (2x10-5newtons/m2). 3.4 Procedure I 3.4.1 Test setup. The test item shall be softly suspended in the test chamber by means of springs or elastic cord.
If a mounting structure is required between the soft suspension and the test item or to hold the soft suspension care must be exercised to assure that no spurious acoustic or vibratory inputs are introduced. The natural frequency of suspension : shall be less than 25 Hz. The test item shall be exposed on every surface to the sound field by centrally locating it in the test chamber. The test item volume shall be no more than 10 percent of the test chamber volume. When the test chamber is rectangular,no major surface of the test item shall be installed para,llelto the chamber wall.
A reverberation t~e test chamber”shall be used and shall be suitably formed and proportioned ~ to produce a duffuse sound field and a uniform sound energy density through- out the enclosure. 515.2-3 METHOD 515.2