Abstract: From one aspect, the invention is a method of making a bending wave panel loudspeaker, comprising rigidly coupling a lever to a panel edge or marginal portion such that the lever extends at an angle to the plane of the panel, coupling a bending wave exciter to the lever whereby bending wave energy is coupled to the panel to produce an acoustic output when the exciter is fed with a signal and supporting the panel on a suspension positioned outboard of the lever. From another aspect the invention is a bending wave panel-form loudspeaker having a lever rigidly coupled to a marginal portion or edge of the panel, a vibration exciter coupled to the lever to apply bending wave energy to the panel to produce an acoustic output and a panel suspension positioned outboard of the lever. From a further aspect, the invention is a small electronic device, e.g.

Abstract: Audio apparatus (30) comprising a piezoelectric transducer (44) and coupling means (54) for coupling the transducer to a user's pinna (32) whereby the transducer excites vibration in the pinna (32) to cause it to transmit an acoustic signal from the transducer (44) to a user's inner ear, characterised in that the transducer is embedded in a casing (42) of relatively soft material and the casing (42) is mounted to a housing (34) of relatively hard material such that a cavity (48) is defined between the casing (42) and housing (34).

Abstract: Acoustic device including a member extending transversely of its thickness and capable of sustaining bending waves at least over an intendedly consequentially acoustically active area of the transverse extent of said member, the member having, by reason of orderly design methodology disclosed and claimed, a distribution of resonant modes of its natural bending wave vibration at least over said area that is dependent on values of particular parameters of said members, including geometrical configuration and directional bending stiffness(es), which values have been selected to predetermine said distribution of natural resonant modes being consonant with required achievable acoustic action of said member for operation of said device over a desired operative acoustic frequency range.

Abstract: A loudspeaker assembly comprising a visual display screen, a resonant panel-form member positioned adjacent to the display screen, and a vibration exciter to cause the panel-form member to resonate as an acoustic resonator. At least a portion of the panel-form member is transparent, through which portion the display screen is visible.

Abstract: Audio apparatus (30) comprising a piezoelectric transducer (44) and coupling means (54) for coupling the transducer to a user's pinna (32) whereby the transducer excites vibration in the pinna (32) to cause it to transmit an acoustic signal from the transducer (44) to a user's inner ear, characterised in that the transducer is embedded in a casing (42) of relatively soft material and the casing (42) is mounted to a housing (34) of relatively hard material such that a cavity (48) is defined between the casing (42) and housing (34).

Abstract: Acoustic device including a member extending transversely of its thickness and capable of sustaining bending waves at least over an intendedly consequentially acoustically active area of the transverse extent of said member, the member having, by reason of orderly design methodology disclosed and claimed, a distribution of resonant modes of its natural bending wave vibration at least over said area that is dependent on values of particular parameters of said members, including geometrical configuration and directional bending stiffness(es), which values have been selected to predetermine said distribution of natural resonant modes being consonant with required achievable acoustic action of said member for operation of said device over a desired operative acoustic frequency range.

Abstract: A bending wave panel-form acoustic radiator formed from sheet material to define an acoustically active area and having at least one integral stiffening member in the form of a corrugation extending out of the plane of the sheet and at least partially across the acoustically active area of the radiator, which stiffening member is of substantially U-shaped cross section. Also disclosed is a method of making a bending wave panel-form acoustic radiator, comprising forming a sheet into a panel having at least one integral corrugation member extending out of the plane of the sheet and at least partly across the sheet and of substantially U-shape cross-section, to stiffen the sheet to have a desired ability to support and propagate bending waves.

Abstract: A panel loudspeaker comprising a panel, at least one driver, and a frame connected to the panel. The panel has a plurality of edges and is capable of sustaining bending waves. The driver is connected to the panel at a location that is neither at or near the edges of the panel, nor at or near the center of the panel, to vibrate the panel to cause it to resonate and produce an acoustic output. The driver location is in a positioning area that lies between a center-of-gravity area, which is centered on the center of gravity of the panel, and an edge area, which abuts the edges of the panel.

Abstract: A method of improving the modal resonance frequency distribution of a panel (2) for a distribution resonant mode bending wave acoustic device involves analysing the distribution of the modal resonance frequencies of the panel, identifying a modal resonance frequency that is non-uniformly spaced relative to adjacent modal resonance frequencies, identifying a location on said panel that exhibits anti-nodal behaviour at said modal resonance frequency and changing the local impedance to bending wave vibration at said location (6). The method has particular application to distributed mode loudspeakers (1).

Abstract: A bending wave loudspeaker comprising a panel-form radiator and an electromechanical vibration exciter coupled to the radiator, wherein the bending stiffness of the radiator is in the range 0.001 to 1000 Nm, wherein the coupling between the exciter and the radiator is such that a component of the applied energy results in compression waves in the radiator and wherein the radiator has a break in mid-plane symmetry resulting in acoustic radiation. A method of making a bending wave loudspeaker comprising selecting a panel-form radiator and an electromechanical vibration exciter, coupling the exciter to the radiator to have a relationship between the electromechanical impedance of the vibration exciter and the mechanical impedance of the radiator useful to the operating bandwidth of the radiator, arranging the bending stiffness of the radiator to be in the range 0.

Abstract: A loudspeaker drive unit comprising a resonant acoustic radiator, an exciter on the radiator to apply bending wave energy to the radiator to cause it to resonate, a support for the loudspeaker drive unit, and means resiliently coupling the exciter to the support.

Abstract: Acoustic device including a member extending transversely of its thickness and capable of sustaining bending waves at least over an intendedly consequentially acoustically active area of the transverse extent of said member, the member having, by reason of orderly design methodology disclosed and claimed, a distribution of resonant modes of its natural bending wave vibration at least over said area that is dependent on values of particular parameters of said members, including geometrical configuration and directional bending stiffness(es), which values have been selected to predetermine said distribution of natural resonant modes being consonant with required achievable acoustic action of said member for operation of said device over a desired operative acoustic frequency range.

Abstract: Acoustic device including a member extending transversely of its thickness and capable of sustaining bending waves at least over an intendedly consequentially acoustically active area of the transverse extent of said member, the member having, by reason of orderly design methodology disclosed and claimed, a distribution of resonant modes of its natural bending wave vibration at least over said area that is dependent on values of particular parameters of said members, including geometrical configuration and directional bending stiffness(es), which values have been selected to predetermine said distribution of natural resonant modes being consonant with required achievable acoustic action of said member for operation of said device over a desired operative acoustic frequency range.

Abstract: A loudspeaker assembly comprising a visual display screen, a resonant panel-form member positioned adjacent to the display screen, and a vibration exciter to cause the panel-form member to resonate as an acoustic resonator. At least a portion of the panel-form member is transparent, through which portion the display screen is visible.

Abstract: A resonant bending wave loudspeaker comprising a panel-form acoustic radiator in the form of a beam and a vibration transducer mounted to the beam at a position to apply bending wave energy thereto to enable low frequency modes to be excited in the radiator both lengthwise of the radiator and crosswise of the radiator, and means mounting the radiator to permit the excitation of low frequency lengthwise and crosswise modes therein.

Abstract: A loudspeaker drive unit comprising a visual display screen, a resonant panel-form member positioned adjacent to the display screen and at least a portion of which is transparent and through which the display screen is visible, and vibration exciting means to cause the panel-form member to resonate to act as an acoustic radiator.

Abstract: A loudspeaker comprising a panel which is sufficiently stiff to support bending waves, the panel having a boundary, a transducer mounted to the panel to apply bending wave energy in the form of dispersive travelling waves thereto at a first location in response to an electrical signal applied to the transducer to cause the panel to vibrate and radiate an acoustic output, the loudspeaker having a frequency range extending from a lower frequency to a higher frequency and the panel having a stiffness giving a coincidence frequency above the lower frequency. Means on or associated with the panel at a second location attenuates travelling bending waves in the panel to prevent or at least substantially to moderate panel resonance.

Abstract: A method of improving the modal resonance frequency distribution of a panel (2) for a distribution resonant mode bending wave acoustic device involves analysing the distribution of the modal resonance frequencies of the panel, identifying a modal resonance frequency that is non-uniformly spaced relative to adjacent modal resonance frequencies, identifying a location on said panel that exhibits anti-nodal behaviour at said modal resonance frequency and changing the local impedance to bending wave vibration at said location (6). The method has particular application to distributed mode loudspeakers (1).

Abstract: A vehicle windscreen accessory comprising a body member, an adjustable support structure for the body member whereby the position of the body member can be adjusted, the body member comprising a mirror member and a loudspeaker having a bending wave panel-form acoustic member, the mirror member and panel-form member being integral. The accessory can be in the form of, e.g., a sun visor or a rear view mirror.

Abstract: An inertial vibration transducer for exciting bending waves in a sound-radiating member has a motor coil assembly with a tubular member adapted to be rigidly mounted directly to the sound-radiating member by adhesive means. The transducer has a magnet assembly supported on a resilient suspension, and the magnet of the magnet assembly may be disposed within the tubular member of the motor coil assembly. Loudspeakers incorporating such transducers also are disclosed.