http://arxiv.org/abs/1911.07575.Copyright © 2020-05-15 by Julius O. Smith III
Center for Computer Research in Music and Acoustics (CCRMA), Stanford University
Since typical speakers have a frequency-dependent radiation pattern, it makes sense to take a multiband approach and combine an array of ``woofers'' with a denser grid of midrange speakers and a yet denser array of ``tweeters,'' for example. In principle, each speaker is assigned a frequency band containing wavelengths up to its diameter or so, and larger wavelengths can be pushed using additional volume-velocity drive. Of course, one large 17-meter (56') diameter diaphragm can handle the entire audio band, but then we have poor spatial resolution at high frequencies.
http://arxiv.org/abs/1911.07575.