Abstract: In its first aspect the invention provides an electromechanical acoustic transducer (5) which is resistively terminated at the rear with a closely-coupled sound absorber (7) made from an aerogel with good acoustic absorption at low frequencies. The invention also provides an aerogel suitable for this use and which is a conglomerate of small particles packed so that there are spaces left therebetween to allow the passage of sound. Moreover, the invention provides an aerogel suitable for this use and comprised of multiple layers (17a etc.) of materials of graded properties, or comprised of material of continuously varying properties throughout the thickness of the absorbing structure, in the principal direction of sound from the source.

Abstract: The present invention relates to a loudspeaker (480), comprising: a support (483); a sound-generating element (481) mounted to the support for vibration to generate sound; and an electro-active device (485) coupled between the support and the sound-generating element for vibrating the sound-generating element (481) in response to an electrical signal.

Abstract: In an electric linear motor, the stator coils are arranged in a line, and the field they produce advances along that line driving the translator along with it. None of the known linear motors can provide all of very high speed, low force, long travel, high linearity and very low moving mass; the present invention proposes an answer in the form of a mechanism that applies motive, displacing force not primarily in the direction along with translator movement is desired but instead approximately at right angles to that direction, the translator being “squeezed” out like a cherry pip squeezed between finger and thumb.

Abstract: In an electric linear motor, the stator coils are arranged in a line, and the field they produce advances along that line driving the translator along with it. None of the known linear motors can provide all of very high speed, low force, long travel, high linearity and very low moving mass; the present invention proposes an answer in the form of a mechanism that applies motive, displacing force not primarily in the direction along with translator movement is desired but instead approximately at right angles to that direction, the translator being “squeezed” out like a cherry pip squeezed between finger and thumb.

Abstract: A loudspeaker has a digital input signal port connected to a digital interpolator to increase the effective sampling rate whose output is fed to a signal delay and magnitude detector after which the short-term dynamic range of the input signal is possibly reduced before application of a unary encoder which encodes the digital input signal into a plurality of unary signals which are then differentially delayed and pulse shaped before application to a plurality of substantially identical acoustic transducers via transducer drivers whose average power drive levels may be controlled by signals derived from the magnitude detector and from a human operator to alter the sound volume produced.

Abstract: A digital pulse-width-modulation (PWM) generator comprising:

Abstract: A linear motor comprising a linearly-extensive stator (1) supporting a translator (2), the stator providing in operation a squeezing force across the translator in a direction approximately orthogonal to the line of the stator, and the translator either having along its movement direction a slightly tapered profile or being mounted on the stator by force-transmitting bearings (3) that when so squeezed deform to become slightly tapered, the effect being to produce a resultant force on the translator that is along the line of the stator. The utilisation of a resilient toroidal bearing member (103) fitted inside and co-axially with a tubular passageway (108) in an outer, sleeve-like bearing body (101) through which an inner bearing body (102) is free to slide. The inner body is then fitted through the toroid, all three components thus being co-axially aligned.