Line-array beam patterns become progressively more directive as frequency rises.

Evidence

An early example of an array loudspeaker was the column loudspeaker. In this arrangement, a number of small loudspeakers were arranged in a closely spaced line. Because of the extended length of the source in one plane, directivity control was achieved in that plane. However, the beam pattern would get progressively more directive with frequency, as predicted by the Fourier transform. Techniques were developed to reduce this behavior, usually by applying the necessary frequencydependent weighting, tapering or windowing using simple electrical circuits, a direct application of the convolution theorem. … Again, this is a direct application of the shift theorems of the Fourier transform. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2902

Categorization

• XREF: Historical lineage of array loudspeakers, connecting Fourier theory to real sound-reinforcement practice.