Abstract: 3D audio virtualization within headphone-type sound reproduction devices, comprises: deriving an HRTF, comprising a PRTF, that includes acoustical effects due to pinnae and ear canals, and a remainder HRTF, that includes acoustical effects due to head, shoulders, torso and other body parts while excluding acoustical effects from pinnae and ear canals; wherein the remainder HRTF is electronically implemented and omits acoustical effects due to pinnae and ear canal effects; and wherein the PRTF is acoustically implemented and personalized to the user through use of two or more transducers positioned such that a front plane of the transducer, the front plane of the transducer's diaphragm, the transducer's mechanical center or the transducer's acoustical center point are 25 mm or more from a user's ear canal entrance, and/or oriented so the 0° axis of acoustical output is aligned with the acoustical output axes of typical external loudspeakers positioned in the acoustical far-field.

Abstract: Head-tracking comprises remixing audio input data or channels to discrete device audio reproduction channels, to alter the audio input data or channels' perceived location in 3D space, in a manner compensating for relative head movement (compensatory manner), based upon provided head location data. Phase (delay) of the desired audio input data or channels is altered to shift the perceived sonic image location in 3D space, in a compensatory manner that correlates to a desired location relative to a designated device reference point. Amplitude of the desired audio input data or channels is altered to shift a perceived sonic image location in 3D space, in a compensatory manner that correlates to the desired location relative to the designated device reference point. Altering phase (delay) is performed using a constant delay function for each of the desired audio input data or channels that is independently varied based on current head location data.

Abstract: 3D audio virtualization within headphone-type sound reproduction devices, comprises: deriving an HRTF, comprising a PRTF, that includes acoustical effects due to pinnae and ear canals, and a remainder HRTF, that includes acoustical effects due to head, shoulders, torso and other body parts while excluding acoustical effects from pinnae and ear canals; wherein the remainder HRTF is electronically implemented and omits acoustical effects due to pinnae and ear canal effects; and wherein the PRTF is acoustically implemented and personalized to the user through use of two or more transducers positioned such that a front plane of the transducer, the front plane of the transducer's diaphragm, the transducer's mechanical center or the transducer's acoustical center point are 25 mm or more from a user's ear canal entrance, and/or oriented so the 0° axis of acoustical output is aligned with the acoustical output axes of typical external loudspeakers positioned in the acoustical far-field.

Abstract: Head-tracking comprises remixing audio input data or channels to discrete device audio reproduction channels, to alter the audio input data or channels' perceived location in 3D space, in a manner compensating for relative head movement (compensatory manner), based upon provided head location data. Phase (delay) of the desired audio input data or channels is altered to shift the perceived sonic image location in 3D space, in a compensatory manner that correlates to a desired location relative to a designated device reference point. Amplitude of the desired audio input data or channels is altered to shift a perceived sonic image location in 3D space, in a compensatory manner that correlates to the desired location relative to the designated device reference point. Altering phase (delay) is performed using a constant delay function for each of the desired audio input data or channels that is independently varied based on current head location data.

Abstract: A panel used in an enclosure for housing at least one electronic component, and an enclosure made of at least one of such panels is disclosed. The panel includes an electrically conductive layer, a separate, magnetically permeable layer connected to the electrically conductive layer, and a separate, extensionally damped layer covering at least 80 percent of a surface of the panel and attached to one or more of the electrically conductive layer and the magnetically permeable layer, where electrical and magnetic conductivity are maintained between all panels of the enclosure, and a ground is provided between circuitry of the electrical component and the electrically conductive layer.

Abstract: A panel used in an enclosure for housing at least one electronic component, and an enclosure made of at least one of such panels is disclosed. The panel includes an electrically conductive layer, a separate, magnetically permeable layer connected to the electrically conductive layer, and a separate, extensionally damped layer covering at least 80 percent of a surface of the panel and attached to one or more of the electrically conductive layer and the magnetically permeable layer, where electrical and magnetic conductivity are maintained between all panels of the enclosure, and a ground is provided between circuitry of the electrical component and the electrically conductive layer.

Abstract: A mechanical mounting system and extensional damping technique for loudspeaker crossover networks. This system decouples the crossover network from the loudspeaker enclosure (cabinet), isolating it from any vibrational energy in the cabinet walls. In addition, an extensional damping material is applied to the crossover network to damp any vibrational energy which may be coupled from the surrounding air into the network. The mounting system can be used for mounting any sensitive electronic components within an enclosure to provide isolation from the walls of the enclosure and from surrounding or environmentally induced vibrational energy.

Abstract: A digital to analog converter according to the principles of the invention provides increased dynamic range by utilizing multiple digital to analog converters (DACs) to provide a balanced output. On the positive side of the topology, two or more DACs connect in parallel to a digital input. A summer adds the DAC outputs to provide the positive side of the balanced output. On the negative side, an inverter provides the negative of the digital input to two or more DACs connected in parallel. A summer adds the DAC outputs to provide the negative side of the balanced output. The averaging effect of the summing operations reduces noise due to random errors, thereby increasing the dynamic range achievable with one DAC. The balanced design of the topology and the use of highly matched components for the positive and negative sides assure that common mode errors, noise and distortion are reduced as well.

Abstract: An arrangement for minimizing acoustic reflections and diffraction from an exterior surface of a diaphragm of a loudspeaker transducer. A layer of highly optimized acoustic foam is applied to an exterior surface of the transducer diaphragm. The acoustic foam is a polyether urethane material of approximately 2 lb/ft.sup.3 density with a skinned bottom surface, optional skinned top surface and optimized cell size and structure. The foam is die cut into a shape to conform to the concave shape of the transducer diaphragm without large air gaps or deformation of the foam. The acoustic foam surface prevents reflection and diffraction of another transducer's output off of the diaphragm of the treated transducer and provides a low pass filtering of the acoustic output of the treated transducer.

Abstract: A loudspeaker enclosure having a constrained layer damping system for minimizing the propagation of vibrations and controlling the resonant modes of the enclosure. The enclosure has a front baffle board on which a plurality of transducers are mounted, and a plurality of other walls mounted to the baffle board to form a cabinet structure. The front baffle board comprises an interior substrate, an exterior substrate, and a constrained layer damping material sandwiched between and bonded to the two substrates. The constrained layer damping material comprises an energy absorbing thermoplastic alloy having a very high material loss factor. The other walls of the enclosure also comprise an interior substrate and an exterior substrate with a constrained layer damping material sandwiched therebetween. An extensional damping material may also be bonded to an interior surface of the interior substrates to further control vibrations in the enclosure.

Abstract: An adjustable, isolation mounting system for center channel loudspeakers has a pair of front mounting feet and a single rear mounting foot extending from a bottom surface of a loudspeaker enclosure. The rear mounting foot is adjustable in height to provide mounting flexibility and stability, and also to adjust the listening axis from the loudspeaker to the listener for optimum sound quality. The rear mounting foot also has a swivel foot member mounted on its bottom end to provide a stable support on irregular mounting surfaces. The front mounting feet are made of a vibration isolating material to isolate vibrations of the loudspeaker enclosure from the mounting surface on which the loudspeaker is supported. A vibration isolating pad is bonded to a recessed bottom surface of the swivel foot member on the rear mounting foot to further isolate vibrations of the loudspeaker enclosure from the mounting surface.

Abstract: A loudspeaker enclosure having a low reflection/low diffraction baffle for reducing acoustic reflections and diffraction. The baffle of the loudspeaker enclosure has a substantially entire front surface covered by a first layer of optimized acoustical foam for reducing acoustic reflections off of the front surface of the baffle and for reducing diffraction around the edges of the enclosure. A second layer of optimized acoustical foam is secured over the mounting flanges of the transducers, which are mounted to the baffle. The first and second foam layers are formed of a thin sheet casted, polyether urethane foam. A front surface of the first layer of foam is flush with a front surface of the second layer of foam. An interference fit is provided between the first and second layers of foam to prevent any gaps from being formed between the first and second layers. The first layer of foam is thicker than the second layer of foam.

Abstract: An optimal transducer mounting system for loudspeakers which optimizes the attachment of a transducer to a loudspeaker enclosure. The mounting system features T-nuts captured between two bonded layers of a baffle board for receiving mounting screws for mounting the transducer to the baffle board. The mounting system also features a highly compressible, extremely low compression-set, airtight gasket disposed between the transducer and the baffle board.

Abstract: A mechanical mounting system and extensional damping technique for loudspeaker crossover networks. This system decouples the crossover network from the loudspeaker enclosure (cabinet), isolating it from any vibrational energy in the cabinet walls. In addition, an extensional damping material is applied to the crossover network to damp any vibrational energy which may be coupled from the surrounding air into the network. The mounting system can be used for mounting any sensitive electronic components within an enclosure to provide isolation from the walls of the enclosure and from surrounding or environmentally induced vibrational energy.