Part 4.2: Elementary acoustic loads of a loudspeaker

Sealed enclosure: in the case of a sealed enclosure, an excursion of loudspeaker membrane remains constant below the resonance frequency. After, it decreases with a slope of 12 dB / oct.

Vented enclosure : vented enclosure has an inertial type impedance at very low frequencies. Below the resonance frequency of Helmholtz resonator, loudspeaker must push the air mass on its rear surface. It then creates two flows in opposite phase (of the loudspeaker membrane and of the vent). At these frequencies, loudspeaker has a great range of excursion. It tends to minimum at a resonance frequency of Helmholtz resonator, for which the mechanical energy is transmitted optimally into the enclosure.