A High Intensity Noise Facility

Abstract

A reverberant-type high intensity noise facility, using horn-type loudspeakers as sources, has been designed and built for environmental testing of missile components. A 120-cu-ft chamber is located inside a 3150-cu-ft room. Using bands of random noise as the input signal, a maximum sound level of 148 db has been produced in the small chamber; levels up to 140 db may be generated in the large room by opening the door of the small chamber. When driven by successive 13 octave bands of random noise with equal voltampere input to the loudspeakers in each band, the sound level is flat within ±5 db from 200 to 3150 cps. Under these conditions the standard deviation of sound levels in various positions in the small chamber relative to the mean sound level decreases from 4 db at 200 cps to less than 1 db at higher frequencies.