Abstract: A display screen (32), e.g., a projection screen comprising a panel having a light reflective surface, characterised in that the screen is a distributed mode acoustic radiator loudspeaker having a transducer (9) mounted wholly and exclusively thereon to vibrate the radiator to cause it to resonate to provide an acoustic output.

Abstract: A trim panel, e.g., a roof lining for a vehicle passenger compartment, characterized in that the trim panel comprises an integral acoustic radiator and a vibration exciter mounted on the radiator to launch bending waves into the radiator to cause it to resonate to produce an acoustic output. The acoustic radiator has a periphery which is integral with the radiator and the trim panel.

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 greetings or the like card (144), characterised by a board (2) forming at least part of the card and in that the board is a distributed mode acoustic radiator having a transducer (9) mounted wholly and exclusively on the radiator to vibrate the radiator to cause it to resonate.

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 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: A loudspeaker (81) comprises an enclosure, an acoustic radiator (2) in the enclosure, a compliant suspension (3) mounting the radiator in the enclosure for pistonic movement relative thereto, and a first transducer (9) for driving the radiator pistonically. The radiator is also excited by a bending wave transducer mounted on the radiator which vibrates the radiator to cause it to resonate. The first transducer varies the air pressure in the enclosure to cause the radiator to move pistonically.

Abstract: A method of and apparatus for producing acoustic output employs a bending wave member to which a number of exciters are coupled over at least part of the area. The exciters are individually addressable to generate impulses in response to digital input that has been suitably shaped and delayed, the impulses being integrated in the panel so that a form of synchronous summation takes place by bending action making use of the dispersive properties of the device. The resulting acoustic output has a reinforced fundamental frequency and reduced harmonics.

Abstract: Electronic apparatus incorporating a loudspeaker, wherein the loudspeaker comprises a bending wave panel member having a user-accessible surface, an electro-acoustic vibration exciter on the panel member to introduce bending wave energy into the panel member in response to an electrical signal applied thereto, and at least one touch sensitive area on or associated with the said user-accessible surface and responsive to user contact.

Abstract: A curved piezoelectric device is attached to a plate to vibrate the plate. Mass-loading is applied to at least one free end of the piezoelectric device to increase output.

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: 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 centres of mass and geometry are featured.

Abstract: A panel-form loudspeaker (81) comprising a resonant distributed mode acoustic radiator (2), and drive means (9) mounted to the radiator to excite multi-mode resonance in the radiator, characterised by a baffle (6, 8) surrounding and supporting the radiator.

Abstract: A vehicle having a passenger compartment with a moulded headlining to which an exciter is coupled and together forming a distributed mode acoustic radiator, the headliner providing a bass acoustic response when resonating. A mid/high frequency acoustic radiator also may be carried by the headlining. Other interior components of the vehicle (seats, door panels, visors, etc.) also may comprise acoustic radiators.

Abstract: A personal computing device, such as a lap-top computer, has a body with a keyboard, a lid with a display screen hinged to the body, a resonant panel loudspeaker carried by the lid and an acoustic waveguide on the lid to direct acoustic output from the loudspeaker. The waveguide comprises a member mounted on the lid, the member being movable on the lid from a retracted/closed position to an advanced/open position.

Abstract: A vehicle having a passenger compartment (102) characterised by a loudspeaker (81) in the passenger compartment comprising a distributed mode acoustic radiator (2) and a transducer (9) mounted wholly and exclusively on the radiator to vibrate the radiator to cause it to resonate.

Abstract: The combination of a personal portable communications device having an audio output intended for use when proximate to a user's ear, and a physically separable accessory to amplify the audio output of the communications device for remote reception. The accessory comprises a bending wave panel-form acoustic radiator, and the communications device has a vibration transducer for coupling to the radiator to drive bending wave energy into the radiator to produce an acoustic output therefrom.

Abstract: A panel-form microphone characterised by a distributed mode acoustic member (12) and a transducer (63) coupled wholly and exclusively to the member to produce a signal in response to resonance of the member due to incident acoustic energy.

Abstract: A panel-form loudspeaker (81) comprising a resonant distributed mode acoustic radiator having a periphery, a transducer (9) mounted to the radiator to excite distributed mode resonance in the radiator, and a frame (1) supporting the radiator, the transducer being coupled between the radiator and the frame to vibrate the panel to cause it to resonate to produce an acoustic output, characterized in that frame supports the radiator round its periphery and by resilient suspension means coupled between the frame and the radiator periphery.

Abstract: A speech recognition method that combines time encoding and hidden Markov approaches. The speech is input and encoded using time encoding, such as TESPAR. A hidden Markov model generates scores; the scores are used to determine the speech element; and the result is output.