Brian G. Ferguson Maritime Operations Div., Defence Sci. and
Technol. Org., P. O. Box 44, Pyrmont 2009, Australia Information
on the various sound sources that contribute energy to the
underwater acoustic environment is often obtained by processing
the data from a thin flexible line array of hydrophones towed
behind a vessel. The acoustic data from the array are processed
digitally in the frequency and spatial domains. The process of
spatial filtering, which is commonly referred to as beamforming,
assumes that the horizontal line array is straight with the
transverse displacements of the hydrophones being zero with
respect to the array axis. Using real acoustic data, this paper
shows the effects on conventional and adaptive beamformers when
these transverse displacements are finite and the array shape is
nonlinear. Furthermore, signal processing techniques are
presented that significantly reduce the influence of these
effects on the performance of the beamformers. By processing the
array's acoustic data when