Abstract: An open audio device with a housing that is configured to be worn on the torso and an acoustic transducer carried by the housing, the acoustic transducer configured to either radiate sound outwardly of the housing or convert received sound into an electrical signal. A structure is coupled to the housing. The structure is proximate to the acoustic transducer. The structure is constructed and arranged to inhibit radiated sound or received sound from being interrupted by a flexible sheet material, such as clothing, located over the housing.

Abstract: An acoustic transducer with an acoustic element that emits or receives front-side acoustic radiation from its front side, and emits or receives rear-side acoustic radiation from its rear side. A housing directs the front-side acoustic radiation and the rear-side acoustic radiation. A plurality of sound-conducting vents in the housing allow sound to enter the housing or allow sound to leave the housing. A distance between vents defines an effective length of an acoustic dipole. The housing and its vents are constructed and arranged such that the effective dipole length is frequency dependent.

Abstract: An open audio device with a housing that is configured to be worn on the torso and an acoustic transducer carried by the housing, the acoustic transducer configured to either radiate sound outwardly of the housing or convert received sound into an electrical signal. A structure is coupled to the housing. The structure is proximate to the acoustic transducer. The structure is constructed and arranged to inhibit radiated sound or received sound from being interrupted by a flexible sheet material, such as clothing, located over the housing.

Abstract: An acoustic transducer with an acoustic element that emits or receives front-side acoustic radiation from its front side, and emits or receives rear-side acoustic radiation from its rear side. A housing directs the front-side acoustic radiation and the rear-side acoustic radiation. A plurality of sound-conducting vents in the housing allow sound to enter the housing or allow sound to leave the housing. A distance between vents defines an effective length of an acoustic dipole. The housing and its vents are constructed and arranged such that the effective dipole length is frequency dependent.

Abstract: An acoustic transducer with an acoustic element that emits or receives front-side acoustic radiation from its front side, and emits or receives rear-side acoustic radiation from its rear side. A housing directs the front-side acoustic radiation and the rear-side acoustic radiation. A plurality of sound-conducting vents in the housing allow sound to enter the housing or allow sound to leave the housing. A distance between vents defines an effective length of an acoustic dipole. The housing and its vents are constructed and arranged such that the effective dipole length is frequency dependent.

Abstract: An acoustic transducer with an acoustic element that emits or receives front-side acoustic radiation from its front side, and emits or receives rear-side acoustic radiation from its rear side. A housing directs the front-side acoustic radiation and the rear-side acoustic radiation. A plurality of sound-conducting vents in the housing allow sound to enter the housing or allow sound to leave the housing. A distance between vents defines an effective length of an acoustic dipole. The housing and its vents are constructed and arranged such that the effective dipole length is frequency dependent.

Abstract: A balanced acoustic device includes an enclosure defining an acoustic chamber, a first passive radiator diaphragm having an active driver assembly and a second passive radiator diaphragm having a plurality of active driver assemblies that are laterally offset. The moving mass of the first passive radiator assembly is substantially equal to the moving mass of the second passive radiator assembly.

Abstract: A balanced acoustic device includes an enclosure defining an acoustic chamber, a first passive radiator diaphragm having an active driver assembly and a second passive radiator diaphragm having a plurality of active driver assemblies that are laterally offset. The moving mass of the first passive radiator assembly is substantially equal to the moving mass of the second passive radiator diaphragm. The lateral offsets of the active driver assemblies in the second passive radiator diaphragm eliminate their interference within the enclosure with the active driver assembly of the first passive radiator diaphragm. Advantageously, a smaller distance between the two passive radiator diaphragms is allowed and therefore a smaller enclosure is possible.

Abstract: An audio system includes a housing and an acoustic exit that exits the housing, and has a configuration that facilitates the grasping of the housing with a plurality of fingers from a single human hand. The acoustic exit is located adjacent an exterior surface of the housing such that the shape of the exit together with the exterior surface facilitates grasping of the housing with a plurality of fingers and the thumb from the single human hand and the acoustic exit exits a back surface of the housing such that the plurality of fingers can be inserted into the exit while the thumb of the same hand can rest on at least one of the top surface and the front surface of the housing.

Abstract: An apparatus includes a housing. A waveguide is located within the housing. The waveguide includes a first subsection that bends around a first axis and has a first cross-sectional area with an aspect ratio that is substantially different from unity. A second subsection bends around a second axis that is non-parallel to the first axis and includes a second cross-sectional area with an aspect ratio that is substantially different from unity. A third subsection acoustically couples the first subsection to the second subsection. The third subsection includes a third cross-sectional area with an aspect ration that varies between the first aspect ratio and the second aspect ratio.

Abstract: An audio device has passive radiators that are driven by acoustic drivers. The passive radiators are arranged so that the net mechanical vibration is minimized.

Abstract: A method for actively suspending a real plant in a vehicle includes modifying a control signal on the basis of a difference between a property of the real plant, as indicated by the response of the real plant to the control signal, and a property of a nominal plant.

Abstract: An apparatus includes a housing. A waveguide is located within the housing. The waveguide includes a first subsection that bends around a first axis and has a first cross-sectional area with an aspect ratio that is substantially different from unity. A second subsection bends around a second axis that is non-parallel to the first axis and includes a second cross-sectional area with an aspect ratio that is substantially different from unity. A third subsection acoustically couples the first subsection to the second subsection. The third subsection includes a third cross-sectional area with an aspect ratio that varies between the first aspect ratio and the second aspect ratio.

Abstract: A load is powered by a power source and a capacitive element in series such that the voltage provided to the load is the sum of the voltages of the power source and the capacitive element. A power converter imposing a limit on a flow of current through at least a portion of the power converter is coupled to the power source and the capacitive element, and selectively causes the capacitive element to either be charged or to discharge depending on the amount of current drawn by the load. As the capacitor discharges, the power source is permitted to supply a relatively higher amount of current to the load.

Abstract: An apparatus has an active suspension including an electromagnetic actuator coupled to a plant in a vehicle. A force bias eliminator is coupled to the plant for causing the actuator to experience a zero-mean load, and a vibration isolation block generates a control signal based on the response of a nominal plant to measured disturbances of the actively suspended plant. A compensation system modifies the control signal in response to a difference between the response of the nominal plant to the control signal and a measured response of the actively-suspended plant to the control signal.

Abstract: An acoustic passive radiator that controls “rocking mode” vibration. An acoustic passive radiator includes a diaphragm for radiating acoustic energy. The diaphragm has a perimeter portion and a central portion. The perimeter portion is thicker than the central portion. The passive radiator further includes a passive radiator suspension. The suspension includes a skin element encasing the diaphragm. The skin element comprises a surround for physically coupling the passive radiator to an acoustic enclosure, pneumatically sealing the diaphragm and the enclosure. The surround has a non-uniform width. The passive radiator a non-pneumatically sealing, non-surround, non-spider suspension element. The non-surround suspension element and the surround coact to control the motion of the diaphragm and to support the weight of the diaphragm.

Abstract: An apparatus includes a housing. A waveguide is located within the housing. The waveguide includes a first subsection that bends around a first axis and has a first cross-sectional area with an aspect ratio that is substantially different from unity. A second subsection bends around a second axis that is non-parallel to the first axis and includes a second cross-sectional area with an aspect ratio that is substantially different from unity. A third subsection acoustically couples the first subsection to the second subsection. The third subsection includes a third cross-sectional area with an aspect ration that varies between the first aspect ratio and the second aspect ratio.

Abstract: A load is powered by a power source and a capacitive element in series such that the voltage provided to the load is the sum of the voltages of the power source and the capacitive element. A power converter imposing a limit on a flow of current through at least a portion of the power converter is coupled to the power source and the capacitive element, and selectively causes the capacitive element to either be charged or to discharge depending on the amount of current drawn by the load. As the capacitor discharges, the power source is permitted to supply a relatively higher amount of current to the load.

Abstract: In response to a change in a circuit parameter of a converter delivering power to a load, the converter is operated in a mode in which additional power is supplied to the load by a capacitive element that is in parallel with the converter, the circuit parameter including a parameter other than input current.

Abstract: An audio device has passive radiators that are driven by acoustic drivers. The passive radiators are arranged so that the net mechanical vibration is minimized.