Abstract: A panel form acoustic member capable of supporting bending wave vibration has the bending wave velocity varied in the region of coincidence to provide a range of coincidence frequencies, for causing the acoustic coupling of the bending waves in the panel to occur over a broader range of angles or for making the coupling more uniform. The member may be incorporated in a loudspeaker having a panel member (1) and an exciter (3) fixed to the panel member to excite bending waves in the loudspeaker to cause an acoustic output.

Abstract: A method of making a vehicle interior trim panel having at least one integral resonant bending wave loudspeaker panel. The method involves designing the trim panel to comprise at least one panel area capable of and intended to operate as a resonant bending wave loudspeaker, making a prototype trim panel to the design, optimising at least one parameter of the prototype panel as concerns its behavior as a resonant bending wave loudspeaker by obtaining the standard deviation, as frequency is varied, of the mechanical impedance of the panel as a function of the at least one parameter, selecting a value or values of said at least one parameter that result in a minimum of said standard deviation of the mechanical impedance of the panel, and making a trim panel in which the at least one parameter to be optimized has the selected value or values.

Abstract: An electro-dynamic inertial vibration exciter (1), for exciting a member (2) having capability to sustain and propagate input vibrational energy comprising a motor coil assembly (3, 4) having a coil (3) rigidly fixed to a tubular coil former member (4), a magnet assembly (5, 6, 7) disposed concentrically with respect to the motor coil assembly, and means (11) suspending the magnet assembly for axial movement relative to the motor coil assembly, characterized by a carrier (9) supporting the motor coil assembly (3, 4) and adapted for connection to the member (2) to be excited.

Abstract: A method of making an acoustic device in the form of a loudspeaker drive unit having a resonant panel-form member adapted to provide an acoustic output when excited with bending wave energy, comprising forming a resilient suspension for the panel-form member by molding and simultaneously fixing the resilient suspension to the panel-form member.

Abstract: A mid/high frequency loudspeaker comprising a stiff lightweight resonant panel form member, a housing in which the panel form member is mounted, a suspension connected between the edges of the panel-form member and the housing and by means of which the panel edges are restrained against movement, the arrangement being such that the housing and the panel-form member together define a cavity, and an electrodynamic exciter for applying bending wave energy to the panel-form member to cause it to resonate to produce an acoustic output, the exciter comprising a magnet assembly rigidly fixed to the housing and defining an annular gap, and a voice coil and coil former assembly disposed in the annular gap and rigidly fixed to the panel-form member near to the geometric center thereof, wherein only said panel suspension centers the voice coil and coil former assembly in the annular gap.

Abstract: An acoustic device, e.g. a loudspeaker, comprising a resonant multi-mode acoustic radiator panel having opposed faces, a vibration exciter arranged to apply bending wave vibration to the resonant panel to produce an acoustic output, a cavity enclosing at least a portion of one panel face and arranged to contain acoustic radiation from the portion of the panel face, wherein the cavity is such as to modify the modal behaviour of the panel. Also disclosed is a method of modifying the modal behaviour of a resonant panel acoustic device, comprising bringing the resonant panel into close proximity with a boundary surface to define a resonant cavity therebetween.

Abstract: Acoustic device comprising a member relying on bending wave action with beneficial distribution of resonant modes thereof, wherein the member has its acoustically active area at least partly bounded by means having a substantially restraining nature in relation to bending wave vibration. Operation can be below coincidence, or above if desired for active acoustic device further having beneficial location of bending wave transducer means determined with reference to and taking account of such bounding means.

Abstract: A method of improving the modal resonance frequency distribution of a panel for a distributed resonant mode bending wave acoustic device. The method 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 the panel that exhibits anti-nodal behaviour at the identified modal resonance frequency, and changing the local impedance to bending wave vibration at that location. The method has particular application to distributed mode loudspeakers.

Abstract: Active acoustic device comprises a panel member (11) having distribution of resonant modes of bending wave action determining acoustic performance in conjunction with a transducer (31-34). The transducer (31-34) is coupled to the panel member (11) at a marginal position. The arrangement is such as to result in acoustically acceptable action dependent on said distribution of active said resonant modes. Methods of selecting the transducer location, or improvement by location of localized marginal clamping, rely on assessing best or better operative interaction of said transducer (31-34) and the panel members (11) according to parameters of acoustic output for the device as an acoustic radiator.

Abstract: A panel-form loudspeaker having a member capable of sustaining and propagating input vibrational energy by bending waves, and a transducer mounted on the member for applying a local couple to the member. The motor coil assembly of the transducer has a surrounding attachment portion rigidly attached to one face of the member in spaced relation to the central attachment portion of the magnet assembly of the transducer. When the transducer is energized, the motor coil assembly and the magnet assembly move in opposite directions to apply a couple to the member through their respective spaced attachment portions to launch bending waves into the member.

Abstract: Active acoustic device comprises a panel member (11) having distribution of resonant modes of bending wave action determining acoustic performance in conjunction with transducer means (31-34). The transducer means (31-34) is coupled to the panel member (11) at a marginal position. The arrangement is such as to result in acoustically acceptable action dependent on said distribution of active said resonant modes. Methods of selecting the transducer location, or improvement by location of localised marginal clamping, rely on assessing best or better operative interaction of said transducer means (31-34) and the panel members (11) according to parameters of acoustic output for the device as an acoustic radiator.

Abstract: Acoustic device comprising a member relying on bending wave action with beneficial distribution of resonant modes thereof, wherein the member has its acoustically active area at least partly bounded by means having a substantially restraining nature in relation to bending wave vibration. Operation can be below coincidence, or above if desired for active acoustic device further having beneficial location of bending wave transducer means determined with reference to and taking account of such bounding means.

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 combination panel-form loudspeaker/light comprising a panel having a front face and rear face, a vibration exciter mounted to the member to excite bending-wave vibration in the member, and a light emitter mounted at or adjacent to the panel and arranged to illuminate an area adjacent to the panel.

Abstract: Acoustic devices have members extending transversely of thickness and capable of sustaining bending waves causing consequential acoustic action by reason of areal distribution of resonant modes of natural bending wave vibration consonant with required achievable acoustic action of said member over a desired operative acoustic frequency range, Areal distribution of stiffness including variation(s) therein is used to get desired locations for bending wave transducers and/or good resonant mode acoustic action from inherently unfavourable shapes of members. Members with combined pistonic active drive and bending wave excitement at centers of mass and geometry are featured.

Abstract: From one aspect the invention is an acoustic device, e.g. a loudspeaker, comprising a resonant multi-mode acoustic radiator panel having opposed faces, a vibration exciter arranged to apply bending wave vibration to the resonant panel to produce an acoustic output, means defining a cavity enclosing at least a portion of one panel face and arranged to contain acoustic radiation from the said portion of the panel face, wherein the cavity is such as to modify the modal behaviour of the panel.

Abstract: Acoustic devices rely on bending wave action in a panel member, particularly distribution of resonant modes of such bending wave action and related acoustically significant surface vibration over area of said panel member favourable to desired or at least acceptable acoustic device performance. The devices comply with selecting parameters of said panel member affecting said distribution, including configuration/geometry and/or bending stiffness(es), and/or location(s) of bending wave transducer(s) in said area of said panel member; the selecting being in accordance with analytical assessment of power transfer related characteristic(s) of said panel member thus said acoustic device concerned and desiderata therefor correlating with achieving said acoustic device performance.

Abstract: Packaging comprises a loudspeaker which has a board component that forms a part of the packaging and acts as a distributed mode bending wave acoustic radiator. A transducer is mounted wholly and exclusively on the radiator to vibrate it and cause it to resonate.

Abstract: An electronic musical instrument having a keyboard and a loudspeaker, wherein the loudspeaker comprises a resonant distributed mode acoustic radiator having a stiff lightweight member having capability to sustain and propagate input vibrational energy by bending waves in at least one operative area extending transversely of thickness, and a transducer mounted wholly and exclusively on the member at a predetermined location or site within the operative area.

Abstract: A loudspeaker/visual display combination comprises a visual display module and a transducer attached to the display module to apply bending wave energy thereto to cause the display module to radiate an acoustic output. Attachment of a transducer directly to the visual display module dispenses with the need for a separate bending wave speaker whilst application of bending wave energy to the module allows satisfactory acoustic performance to be obtained.