Enclosures prevent acoustic short-circuiting that silences low frequencies

Evidence

The first problem is that at low frequencies the sound pressure difference around the edge of the diaphragm will be cancelled (‘short-circuited’) since the distance is much less than that of a wavelength, and the element radiates very little sound. To prevent cancellation of the pressure difference, the element must be attached to an enclosure or a baffle. The two most common solutions are closed box and bass-reflex loudspeakers. … The advantage of this resonance is that it adds sound radiation and helps to boost this low frequency range. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 469

Categorization

• DEFINE: Explains ‘short-circuiting’ of pressure difference and the Helmholtz-resonator basis of bass-reflex designs.