Abstract: An ear protection device (10) to fit in a user's ear comprises an inner core (20) of non-compressible rigid material which is a metal or ceramic, and a compressible and resilient suspension layer (40), covering at least part of the inner core (20), for suspending and cushioning said device in a user's ear. The suspension layer (40) may comprise memory foam. The materials of the inner core (20), and of the suspension layer (40) differ very significantly in their characteristic impedances, so sound transmission from one material to the other is inhibited, and sound propagation through the ear canal is very largely prevented.

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: 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.

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.