Directivity of any uniformly driven aperture depends on wavelengths fitting its length

Evidence

Because of the convolution theorem discussed earlier, this equation applies to continuous sources, for example, horn mouths, as well as to speaker arrays. This means that the directivity of a uniformly driven speaker array or a uniformly illuminated horn mouth is a function of the number of wavelengths that fit into the size L. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2936

Categorization

• XREF: The convolution theorem from earlier chapters makes discrete arrays and continuous horns mathematically interchangeable — a unifying concept worth resurfacing.