Directional horns suppress spatial aliasing when they control directivity below the aliasing frequency.

Evidence

One can see that the aliased main lobes have been eliminated. In fact, the response has become equivalent to a continuous line source of the same extent as the array. Clearly, using directional sources, such as constant-directivity horns, can also be used to achieve similar effects. It is this that results in the success of large arrays based on them, providing the horns have directivity control before spatial aliasing occurs. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2911

Categorization

• DEFINE: Spatial aliasing here means spurious grating lobes appearing once element spacing exceeds half a wavelength; directional sources filter them out.