Abstract: In a digital audio broadcast system, to utilize transmission bandwidth efficiently, representations of a stereo audio signal for transmission are generated in accordance with an inventive multidescriptive coding technique. The representations, as generated, are then transmitted through multiple communication channels, respectively. The transmitted representations are received by a receiver where one or more of the representations are selected for recovery of the stereo audio signal. Because of the design of the multidescriptive coding used, the more representations are selected to recover the stereo audio signal, the higher the quality of the recovered signal.

Abstract: A loudspeaker system having wide-directional characteristics includes a loudspeaker body having a polyhedron shape, preferably of dodecahedron and a plurality of speakers disposed on outer surfaces, respectively, of the polyhedron-shaped loudspeaker body in a manner that axial lines of adjacent two speakers intersect each other at a predetermined angle. A correction filter is further operatively connected to the speakers, and the correction filter provides a correction value set so as to obtain a flatness of sound pressures at various portions around the loudspeaker body.

Abstract: An interface circuit for interconnecting the fixed controls of a vehicle to a replacement stereo. The interface circuit is capable of receiving control signals from fixed controls, such as steering wheel controls, backseat controls, handlebar controls, and the like, and then transmitting corresponding control signals to a replacement stereo. In one embodiment, the output signals from the interface circuit are comprised of wireless signals, such as IR signals. In another embodiment, the interface device is programmable such that the interface device can be programmed to emit signals corresponding to the same signals that would be emitted from a handheld remote control sold in conjunction with an after-market stereo receiver.

Abstract: An audio decoder solution is here provided where a reduction in computing power is required. The proposed method consists of forcing the multiple output channels to only one type of inverse transformation format. A format of long transform length is more suitable for input signals whose spectrum remains stationary or quasi-stationary. This provides a greater frequency resolution, improved coding performance and a reduction of computing power required. Another format of two or more short transform lengths, possessing greater time resolution, is more desirable for rapidly changing signals with time. The computer power required for two or more short transforms should be higher than for only one transformation. The time versus frequency resolution trade-off should be considered when selecting a transform block length. Advantage is taken of human hearing behaviour to reduce the computing power of a processing engine (e.g. DSP) when downmixing from an M-channel input to a P-channel output is required.

Abstract: A system, more particularly a hearing aid, consisting of a microphone and a preamplifier, wherein the microphone comprises a housing having therein an opening to the surroundings, a diaphragm and a backplate, while the amplifier is coupled to the system consisting of the diaphragm and the backplate and has a field effect transistor as input element. In the housing, in a space which is bounded by, on the one hand, the diaphragm and, on the other, the housing wall, and which does not comprise the opening to the surroundings, a pressure equalization opening is present, which has a diameter such that in the audible audiospectrum it does not make an essential contribution to the suppression of low frequencies. In the input stage of the amplifier, at the output of the field effect transistor, a low-pass filter or a high-pass filter or a combination thereof is arranged. Through this measure, the frequency characteristic can be optimally influenced to suppress noise.

Abstract: In an electromagnetic induction type speaker apparatus, individual constants are set in such a manner that the following formula is satisfied N×(R1×R2)1/2/{2 ?×L1×(1?k2)1/2}?20000 where R1 is the DC resistance of a primary coil 15: L1 is the inductance of the primary coil 15; N is the number of turns of the primary coil 15; R2 is the DC resistance of the secondary coil 18; L2 is the inductance of the secondary coil 18; and k is the coupling coefficient of the primary coil 15 and the secondary coil 18. In addition, the constants L1 and L2 are selected in such a manner that the ratio of the inductance L1 and the inductance L2 becomes equal to in the ratio of the DC resistance R1 and the DC resistance R2.

Abstract: A dual bar audio level meter for a digital audio signal with dynamic range control decodes the digital audio signal to produce a full range audio signal and control parameters. A reduced range audio signal is derived from the full range audio signal using the control parameters, and the reduced and full range audio signals are processed to present a display having a pair of bars for each channel of the digital audio signal. The dual bars may be in the form of an inner bar representing the full range audio signal and an outer bar encompassing the inner bar representing the reduced range audio signal. A dual peak indicator also may be used to provide peak information for each channel.

Abstract: A parametric loudspeaker which uses multiple piezoelectric bimorph transducers. These multiple piezoelectric bimorphs have a resonant frequency which varies from unit to unit. The phase response at and near the resonant frequency changes at a very high rate with slight changes in frequency. The associated modulator electronics have a primary carrier frequency that is optimized for maximum parametric output. This is achieved by aligning the carrier frequency with the flattest portions of the phase curve for maximum phase coordination among the multiple devices.

Abstract: A loudspeaker system, which has the ability to create a homogeneous sound over large distances, comprising at least one line-source of acoustical radiation, each comprising three or more essentially identical speaker-units arranged adjacent to each other at a center-to-center spacing D1, and at least one elongated high frequency transducer arranged in parallel with said line source(s), said elongated high frequency transducer(s) having an essentially continuous radiating surface along the axis of elongation. Where the crossover frequency FCR and the distance D1, for said line-source(s), is set according to new design criteria, taking into account the frequency response from said speaker units in said line-sources and the optimal performance for a line-source. A method is also included, by which a homogeneous sound over large distances can be accomplished.

Abstract: Provided is a method (500) and audio circuit (100) for reducing popping noise in a load (140, 145) connected to the audio circuit, especially during audio circuit start-up. The method applies a time varying voltage (364) to the load that has a smooth, S-shaped curve when plotted over time. The device include an integrated circuit (IC) set as a channel block (110), a load connected between the channel block and ground, a bypass control (150) connected to the channel block for producing a controlled ground reference voltage having an S-shaped curve to the channel block, a shunt control (170) controlling the voltage delivered across the load, and a ground capacitor (160) coupled between the bypass control and ground. The channel block typically includes an amplifier which supplies the output voltage across the load. The bypass circuit generally includes a bypass generator and a transistor selectively providing a charge to the ground capacitor.

Abstract: An electronic stethoscope comprises a headpiece, a chest-piece and two earpieces. The headpiece is fitted with a display arrangement in the form of a liquid-crystal display. A microphone, one or more sensors and fixed electrodes and movable electrodes are mounted in the headpiece. The movable electrodes are fixed to pivoted arms which form a contact ring.

Abstract: A click-muting circuit for a headset microphone connected to a telephone, comprising a user operated mute switch, a click eliminator circuit connected across the microphone for gradually creating a short circuit across the microphone in response to closure of the mute switch, and a hard muting circuit connected in series with the microphone for disconnecting the microphone after the short circuit has been established.

Abstract: The present invention relates to a compact audio speaker assembly for a portable computer. The portable computer has a lower housing having a first opening on a side surface, a upper housing having a second opening corresponding to the first opening and coupled to the lower housing to form an internal space, and a speaker assembly installed in the internal space and held by the lower housing and the upper housing. An end surface of the speaker assembly is exposed outwardly through the first opening and the second opening.

Abstract: An Automatic Noise Reduction system wherein the Q of the frequency response is reduced using a negative output resistance to substantially eliminate the coil resistance of a speaker in a headset. The resulting system is less sensitive to variations in operating parameters, such as headset fit on a user and component variations. Temperature compensation of a negative output resistance amplifier is introduced to maintain stability over a wide range of operating temperatures. Temperature compensation includes substantially matching the temperature coefficient of the negative output resistance amplifier to the temperature coefficient of the speaker coil.