Abstract: A headphone or earphone (10; 50) consists of a casing (12) adapted to fit to a user's ear, the casing (12) enclosing a driver (22) with a diaphragm. Behind the driver (22) is a rear closure element (15; 52); and the driver (22) is clamped against at least one resilient element (23) that engages with its front face near the periphery, or alternatively is clamped between two such resilient elements (23, 24). The casing (12) defines a cavity in front of the driver (22) that communicates with a sound outlet duct (18) adapted to provide sound to the user's ear. The sound outlet duct (18) may define a restrictive duct portion with a cross-sectional area between 18% and 28% of the cross-sectional area of the diaphragm. Behind the driver (22) may be an enclosed airtight cavity, or alternatively the rear closure element (52) may define a rear outlet duct (54) aligned with the sound outlet duct (18).

Abstract: A panel (10) for sound suppression consists of a multiplicity of rigid elements (12) that extend parallel to each other, with gaps between adjacent rigid elements. Within each gap a vortex chamber (15) is defined to attenuate acoustic waves. The elements (12) may have curved edge portions (14), the edge portions (14) of adjacent elements (12) overlapping to define the vortex chamber (15), and also defining a first channel (16a) and a second channel (16b) communicating with the vortex chamber (15) at its periphery and aligned with a tangential component, such that if a fluid were to flow in through either channel (16a or 16b) the fluid would enter the vortex chamber (15) with a rotational sense relative to the vortex chamber (15), the rotational sense being the same for both the channels (16a, 16b). Such a sound-attenuating panel may for example be used as part of a wall of a loudspeaker housing (50).

Abstract: A headphone or earphone (10; 50) consists of a casing (12) adapted to fit to a user's ear, the casing (12) enclosing a driver (22) with a diaphragm. Behind the driver (22) is a rear closure element (15; 52); and the driver (22) is clamped against at least one resilient element (23) that engages with its front face near the periphery, or alternatively is clamped between two such resilient elements (23, 24). The casing (12) defines a cavity in front of the driver (22) that communicates with a sound outlet duct (18) adapted to provide sound to the user's ear. The sound outlet duct (18) may define a restrictive duct portion with a cross-sectional area between 18% and 28% of the cross-sectional area of the diaphragm. Behind the driver (22) may be an enclosed airtight cavity, or alternatively the rear closure element (52) may define a rear outlet duct (54) aligned with the sound outlet duct (18).

Abstract: A panel (10) for sound suppression consists of a multiplicity of rigid elements (12) that extend parallel to each other, with gaps between adjacent rigid elements. Within each gap a vortex chamber (15) is defined to attenuate acoustic waves. The elements (12) may have curved edge portions (14), the edge portions (14) of adjacent elements (12) overlapping to define the vortex chamber (15), and also defining a first channel (16a) and a second channel (16b) communicating with the vortex chamber (15) at its periphery and aligned with a tangential component, such that if a fluid were to flow in through either channel (16a or 16b) the fluid would enter the vortex chamber (15) with a rotational sense relative to the vortex chamber (15), the rotational sense being the same for both the channels (16a, 16b). Such a sound-attenuating panel may for example be used as part of a wall of a loudspeaker housing (50).

Abstract: An acoustic device (90) for use with a movable loudspeaker element (12), the acoustic device defining an enclosure (16) with an aperture to locate the movable loudspeaker element (12), and with a port (20, 28) communicating with the outside of the enclosure, wherein the acoustic device includes at least one sound-suppressing duct (22) incorporating at least one vortex chamber (24) to absorb sound waves propagating through the duct and so suppress sound waves from the port. The acoustic device (90) may be a driver or a frame for a driver; alternatively it may be a loudspeaker or a housing for a loudspeaker.

Abstract: A loudspeaker (130) comprises an electro-acoustic transducer such as a loudspeaker driver (135) mounted to a housing. The housing has side walls (132) subjected to a compressive force by bolts (50), which may extend between rigid end plates (133, 134). The side walls may be formed by a stack of plates. The housing defines a recess such that when the loudspeaker driver (135) is mounted in the housing, there is a cavity behind the loudspeaker driver (135). Such a housing may be used for a range of different electro-acoustic transducers. The compressive force suppresses resonance and improves performance of the electro-acoustic transducer.