Vertical Directionality of Ambient Noise: 150-300 Hz

摘要

Measurements of the vertical directionality of ambient noise in the 150-300 Hz region have been reported. The 48 element NORDA VEKA array cut for 300 Hz and centered on the sound axis (750 m) was used to collect the data. Three features of the data are striking: (1) short term stability and long term fluctuations of the vertical structure, (2) asymmetry in the levels observed by the upward and downward looking beams, and (3) the existence of an underlying boxcar characteristic to the vertical structure on top of which are substantial fluctuations often taking the form of horns at + or - 10-14 degrees with a significant notch in the + or - 9-10 degrees region. Keywords: Acoustic arrays; Fast fourier transforms; Contrack VIII exercise.