Abstract: A device for measuring a body temperature includes an earbud configured for insertion into at least a portion of an ear canal of a user to thereby create a substantially sealed ear canal. A temperature sensing element is fixed to the earbud at a location in which the temperature sensing element is thermally coupled to air in the sealed ear canal when the earbud is at least partially inserted into the ear canal. The temperature sensing element has a temperature-dependent electrical characteristic. The temperature sensing element is in electrical communication with a circuit that is configured to determine a temperature of the air in the sealed ear canal of the user in response to the temperature-dependent electrical characteristic.

Abstract: An apparatus includes an enclosure capable of receiving a transducer for converting electrical signals into audible signals. The apparatus also includes one or more structures within the enclosure defining one or more channels, each channel having one end located within the enclosure and another end that is external to the enclosure. The apparatus also includes an acoustic resistive element located in the one of the one or more structures, the acoustic resistive element being capable of changing the acoustic characteristics of at least one of the one or more channels within the enclosure.

Abstract: A device for measuring a body temperature includes an earbud configured for insertion into at least a portion of an ear canal of a user to thereby create a substantially sealed ear canal. A temperature sensing element is fixed to the earbud at a location in which the temperature sensing element is thermally coupled to air in the sealed ear canal when the earbud is at least partially inserted into the ear canal. The temperature sensing element has a temperature-dependent electrical characteristic. The temperature sensing element is in electrical communication with a circuit that is configured to determine a temperature of the air in the sealed ear canal of the user in response to the temperature-dependent electrical characteristic.

Abstract: An apparatus includes an enclosure capable of receiving a transducer for converting electrical signals into audible signals. The apparatus also includes one or more structures within the enclosure defining one or more channels, each channel having one end located within the enclosure and another end that is external to the enclosure. The apparatus also includes an acoustic resistive element located in the one of the one or more structures, the acoustic resistive element being capable of changing the acoustic characteristics of at least one of the one or more channels within the enclosure.

Abstract: A loudspeaker comprising includes an enclosure, a driver element located within the enclosure and including a cone diaphragm, a first cavity defined by a first cavity wall and the cone diaphragm, the first cavity extending from the cone diaphragm and having a first opening which has an area less than an area of the cone diaphragm, an exit element extending from the first opening of the first cavity and acoustically coupling the first cavity to an environment outside of the enclosure, a second cavity, defined by a second cavity wall within the enclosure extending from a second opening in the first cavity, and an acoustic element in the second opening acoustically coupling the second cavity to the first cavity. The second cavity is not otherwise acoustically coupled to the environment outside of the enclosure.

Abstract: An electroacoustic transducer includes a housing and a moving portion adapted to move relative to the housing. The moving portion has a first surface and includes a first electrode. A second electrode on a first surface of the housing is located proximate to a first region of the first electrode, and a third electrode on the first surface of the housing is located proximate to a second region of the first electrode. A capacitance between the first and second electrodes and a capacitance between the first and third electrodes vary similarly with displacement of the moving portion relative to the housing. An impedance buffer is coupled to the second electrode and the third electrode.

Abstract: A loudspeaker comprising includes an enclosure, a driver element located within the enclosure and including a cone diaphragm, a first cavity defined by a first cavity wall and the cone diaphragm, the first cavity extending from the cone diaphragm and having a first opening which has an area less than an area of the cone diaphragm, an exit element extending from the first opening of the first cavity and acoustically coupling the first cavity to an environment outside of the enclosure, a second cavity, defined by a second cavity wall within the enclosure extending from a second opening in the first cavity, and an acoustic element in the second opening acoustically coupling the second cavity to the first cavity.

Abstract: In an aspect, in general, a loudspeaker element includes an enclosure, a cone diaphragm of a driver element located within the enclosure, a first cavity wall extending from the cone diaphragm of the driver element to a throat opening which has an area less than an area of the cone diaphragm and forming a first cavity within the enclosure, an exit element extending from the throat opening to an environment outside of the enclosure, and an impedance compensation element extending from the first cavity wall, the impedance compensation element including a second cavity wall which forms a second cavity within the enclosure and a resistance element separating the second cavity from the first cavity.

Abstract: An electroacoustic transducer for converting electrical input signals into acoustic output signals includes a diaphragm adapted to move relative to a housing in response to the electrical input signals to produce the acoustic output signals, a displacement sensor, a bias voltage source, and an amplifier. The displacement sensor includes a first electrode adhered to the diaphragm and a second electrode on a first surface of the housing located proximate to the first electrode. A capacitance between the first electrode and the second electrode varies with a displacement of the diaphragm relative to the housing. The bias voltage source is coupled to at least one of the first electrode or the second electrode and provides a fixed charge to the electrode to which it is attached. The amplifier amplifies a change in voltage between the first and second electrodes to produce an output voltage between first and second signal outputs.

Abstract: An acoustic horn. In one implementation, the horn includes at least four wall sections, defining a passageway. The cross-sectional area of the mouth is at least ten times the cross sectional area of the throat. The wall sections are dimensioned so that at least one wall section has a dimension at the throat at least ten times a dimension at the throat of a second wall section. In another implementation the cross-section at the mouth is elongated and is be bounded by a continuous curve defining a geometric figure having a major axis at least ten times a minor axis.

Abstract: An acoustic horn. In one implementation, the horn includes at least four wall sections, defining a passageway. The cross-sectional area of the mouth is at least ten times the cross sectional area of the throat. The wall sections are dimensioned so that at least one wall section has a dimension at the throat at least ten times a dimension at the throat of a second wall section. In another implementation the cross-section at the mouth is elongated and is be bounded by a continuous curve defining a geometric figure having a major axis at least ten times a minor axis.

Abstract: In an aspect, in general, a loudspeaker element includes an enclosure, a cone diaphragm of a driver element located within the enclosure, a first cavity wall extending from the cone diaphragm of the driver element to a throat opening which has an area less than an area of the cone diaphragm and forming a first cavity within the enclosure, an exit element extending from the throat opening to an environment outside of the enclosure, and an impedance compensation element extending from the first cavity wall, the impedance compensation element including a second cavity wall which forms a second cavity within the enclosure and a resistance element separating the second cavity from the first cavity.

Abstract: An electroacoustic transducer for converting electrical input signals into acoustic output signals includes a diaphragm adapted to move relative to a housing in response to the electrical input signals to produce the acoustic output signals, a displacement sensor, a bias voltage source, and an amplifier. The displacement sensor includes a first electrode adhered to the diaphragm and a second electrode on a first surface of the housing located proximate to the first electrode. A capacitance between the first electrode and the second electrode varies with a displacement of the diaphragm relative to the housing. The bias voltage source is coupled to at least one of the first electrode or the second electrode and provides a fixed charge to the electrode to which it is attached. The amplifier amplifies a change in voltage between the first and second electrodes to produce an output voltage between first and second signal outputs.

Abstract: An electroacoustic transducer includes a housing and a moving portion adapted to move relative to the housing. The moving portion has a first surface and includes a first electrode. A second electrode on a first surface of the housing is located proximate to a first region of the first electrode, and a third electrode on the first surface of the housing is located proximate to a second region of the first electrode. A capacitance between the first and second electrodes and a capacitance between the first and third electrodes vary similarly with displacement of the moving portion relative to the housing. An impedance buffer is coupled to the second electrode and the third electrode.

Abstract: An electro-acoustic transducer has an electro-magnetically driven moving dome and a phase plug having a body and a dome-interface surface, with a compression cavity formed between the dome and the dome-interface surface. The phase plug includes at least first and second annular slots beginning at the dome-interface surface and extending a first depth into the body of the phase plug. The first and second slots are separated by a bridge element at the dome-interface surface and joined by a first bridge passage at the first depth beneath the dome-interface surface. The phase plug also includes an exit slot coupling the bridge passage to a throat at a second depth in the body of the phase plug.

Abstract: An electro-acoustic transducer has an electro-magnetically driven moving dome and a phase plug having a body and a dome-interface surface, with a compression cavity formed between the dome and the dome-interface surface. The phase plug includes at least first and second annular slots beginning at the dome-interface surface and extending a first depth into the body of the phase plug. The first and second slots are separated by a bridge element at the dome-interface surface and joined by a first bridge passage at the first depth beneath the dome-interface surface. The phase plug also includes an exit slot coupling the bridge passage to a throat at a second depth in the body of the phase plug.

Abstract: A waveguide system for radiating sound waves. The system includes a low loss waveguide for transmitting sound waves, having walls are tapered so that said cross-sectional area of the exit end is less than the cross-sectional area of the inlet end. In a second aspect of the invention, a waveguide for radiating sound waves, has segments of length approximately equal to A ? ( y ) = A inlet ? [ 1 - 2 ? Y B + ( y B ) 2 ] where l is the effective length of said waveguide and n is a positive integer. The product of a first set of alternating segments is greater than the product of a second set of alternating segments, in one embodiment, by a factor of three. In a third aspect of the invention, the first two aspects are combined.

Abstract: A waveguide system for radiating sound waves. The system includes a low loss waveguide for transmitting sound waves, having walls are tapered so that said cross-sectional area of the exit end is less than the cross-sectional area of the inlet end. In a second aspect of the invention, a waveguide for radiating sound waves, has segments of length approximately equal to A ? ( y ) = A inlet ? [ 1 - 2 ? Y B + ( y B ) 2 ] where l is the effective length of said waveguide and n is a positive integer. The product of a first set of alternating segments is greater than the product of a second set of alternating segments, in one embodiment, by a factor of three. In a third aspect of the invention, the first two aspects are combined.

Abstract: A waveguide system for radiating sound waves. The system includes a low loss waveguide for transmitting sound waves, having walls are tapered so that said crosssectional area of the exit end is less than the cross-sectional area of the inlet end. In a second aspect of the invention, a waveguide for radiating sound waves, has segments of length approximately equal to A ⁡ ( y ) = A inlet ⁡ [ 1 - 2 ⁢ Y B + ( Y B ) 2 ] where l is the effective length of said waveguide and n is a positive integer.