Abstract: In an acoustical speaker having a movable diaphragm responsive over a range of frequencies, an air duct having a cross-sectional area less than that of the diaphragm substantially surrounding the diaphragm and in communication with one side thereof for acoustically isolating the diaphragm, dampening low-frequency ringing and acoustically loading the diaphragm for extending the frequency range to lower frequencies to enhance the performance of the speaker with small speaker enclosures. One embodiment provides for similar ducting for passive radiator diaphragms.