Abstract: A system and process for estimating the time delay of arrival (TDOA) between a pair of audio sensors of a microphone array is presented. Generally, a generalized cross-correlation (GCC) technique is employed. However, this technique is improved to include provisions for both reducing the influence (including interference) from correlated ambient noise and reverberation noise in the sensor signals prior to computing the TDOA estimate. Two unique correlated ambient noise reduction procedures are also proposed. One involves the application of Wiener filtering, and the other a combination of Wiener filtering with a Gnn subtraction technique. In addition, two unique reverberation noise reduction procedures are proposed. Both involve applying a weighting factor to the signals prior to computing the TDOA which combines the effects of a traditional maximum likelihood (TML) weighting function and a phase transformation (PHAT) weighting function.

Abstract: A system and process is described for estimating the location of a speaker using signals output by a microphone array characterized by multiple pairs of audio sensors. The location of a speaker is estimated by first determining whether the signal data contains human speech components and filtering out noise attributable to stationary sources. The location of the person speaking is then estimated using a time-delay-of-arrival based SSL technique on those parts of the data determined to contain human speech components. A consensus location for the speaker is computed from the individual location estimates associated with each pair of microphone array audio sensors taking into consideration the uncertainty of each estimate. A final consensus location is also computed from the individual consensus locations computed over a prescribed number of sampling periods using a temporal filtering technique.

Abstract: A method is described, wherein multiple input signals are subjected to a combination process of adaptive beamforming and adaptive echo cancelling, and wherein for each of the input signals an individual processing history of adaptive echo cancelling data is kept and combined with current adaptive beamforming data. Accordingly an audio processing device is described which comprises at least one parallel acoustic paths for providing respective inputs signals, the acoustic paths are connected in series to beamformer paths, and the device comprises an adaptive beamformer and an adaptive echo canceller for performing adaptive beamforming and adaptive echo cancelling respectively, whereby the adaptive echo canceller is provided with storage means for storing in relation to every input signal, individual processing histories of adaptive echo cancelling data for combination with current adaptive beamforming data.

Abstract: A midrange loudspeaker for operation in conjunction with low-frequency and high-frequency loudspeaker modules in a theater sound system, having a reduced depth for deployment in limited space. The midrange module is configured with a plurality of drivers and a waveguide unit that provides uniform sound coverage throughout a theater auditorium with substantially seamless crossovers at 250 Hz and 1.5 kHz and with the vertical beam-width held substantially constant by an electrical filter network.

Abstract: A highly discreet and accurate voice pickup device includes a standard miniature pressure gradient type microphone element provided and mounted very close to the side of the user's head, preferably near the user's ear. The microphone element is oriented so that its direction of maximum sensitivity is parallel to the side of the user's head, and points toward the user's mouth so that it will pick up the user's speech sounds as the sounds diffract and travel along the side of the user's face and head, to the microphone element. The microphone element can be configured with low pass networks at front and rear ports of the microphone element, which cooperate with air volumes within the microphone to provide additional directional properties that advantageously vary with frequency and further enhance the noise-rejection capability of the microphone element.

Abstract: An audio circuit has an function of removing noise signals before sending audio signals to a sounder. The circuit includes a mute detector for detecting a mute portion of the audio signals, an audio signal amplifier for amplifying the audio signals, and a noise canceler for canceling noise signals mixing with the audio signals by utilizing the noise signals picked up by the mute detector in the mute portion of the audio signals.

Abstract: Sound reproduction and reinforcement systems and methods are presented herein for spatially enhancing stereo images typically used such performances as those involving music. The embodiments seek to expand the amount of audience area that would receive a sound image that maintains sound reproduction fidelity regarding spatial orientation of sound sources involved in an original performance. To expand the audience area receiving spatially faithful sound reproduction certain characteristics of sound have been first studied to find important factors involved.

Abstract: It is usual to utilize electric current filters for electroacoustic transducers, the filters are in general frequency mixers. Audio electric signals have a pulse response quality and excellent frequency adjustment. As for electroacoustic transducers, the transformation is not properly carried out for electroacoustic transducers. The electric pulses travel at the speed of the electrons whereas the membrane and its motor have a specific weight. The weight has a mechanical inertia preventing an instantaneous response to the electric effects. A method can modify at least one modulation of the original electric pulse into micro electrical phase shifts. The micro phase shifts are generated by impedance of the components. An apparatus has several components of similar type mounted in parallel, thereby forming a self-powered oscillator, energized by the original electric signal. The apparatus is mounted on the circuit powering the enclosure.

Abstract: A wireless speaker system used in conjunction with a hard-wired audio system is provided. The wireless speaker system includes a wireless transmitter module including an input connected to a wired speaker output of a main component of the hard-wired audio system. The wireless transmitter module transmits an output signal of a predefined frequency carrying the output signal of the main component. A wireless receiver module including an output connected to the wired speaker input of the external speaker receives the output signal on the predefined frequency and the external speaker responds to the output signal.

Abstract: A method of reducing a noise generated from a speaker at the time of power on/off in an audio output device that drives the speaker. The device includes a digital DC attenuator, a D/A converter, and an operational amplifier. The attenuator gradually changes an output digital value from a first digital value to a second digital value. The converter converts an output from the attenuator into an analog signal. The amplifier amplifies an output from the converter and drives a speaker. At the time of power on, the output from the attenuator is gradually changed from a digital value corresponding to the ground level to a digital value corresponding to the signal ground value. At the time of power off or system reset, the output from the attenuator is gradually changed from the digital value corresponding to the signal ground value to the digital value corresponding to the ground level.

Abstract: An apparatus and method for generating a muting signal. The apparatus includes an audio signal detector for remotely receiving an audio signal and a processor in communication with the detector. The processor is configured to compare the received audio signal with a predetermined audio signal generated by a device and generate a muting signal when at least a component of the received audio signal matches the predetermined audio signal.

Abstract: An air induction system comprises an air induction body and air filter to provide filtered air to a vehicle engine. A microphone is disposed within the air filter. A control unit may receive signals from the microphone. The control unit may further control a speaker, which produces a noise canceling sound to thereby reduce engine noise associated with the air induction system.

Abstract: There is provided a surround device which processes stereo signals decoded by a decoder of a multi-channel surround method comprises boost means which boosts middle and low frequency components of a center channel signal in the stereo signals. There is also provided a surround device which processes stereo signals decoded by a decoder of a Dolby Pro Logic method comprises boost means which boosts high frequency components of a surround channel signal in the stereo signals. The boost means is composed of a level detector for detecting an output level of the channel signal, an operation portion for calculating and determining an amount of boost based on a result of the level detector, and a signal boost portion for boosting the channel signal based on a result of the operation portion.

Abstract: A semiconductor memory card for storing audio information with corresponding text information and type information, where the type information indicates a type of the text information. The type is classified into at least (a), (b), and (c) in which the text information respectively includes (a) a 1-byte character code sequence, (b) a 2-byte character code sequence, and (c) a 1-byte character code sequence and a 2-byte character code sequence.

Abstract: A method of processing and reproducing an input audio stereo signal in an audio signal processing system comprises the steps of (1) splitting a side signal into a first and a second intermediate signal, where the first intermediate signal is equal to the side signal and the second intermediate signal is equal to the first intermediate signal phase shifted 180°, (2) attenuating the mid signal by a factor a which compensates for imperfections in the balance between the mid and side signals appearing in the audio reproduction stage, (3) adding the attenuated mid signal to both of the first and second intermediate signals, so as to form the output audio stereo signal, and (4) directing the output stereo signal to an audio stereo signal reproduction system, comprising a pair of loudspeaker units located in close proximity to each other.

Abstract: A quasi-differential power amplifier and method are disclosed that enhance drive capability and dynamic range by driving a right, left and common terminals with a right channel output signal, a left channel output signal, and a common mode output signal that are each a combination of the left and right channel input signals. In addition, the common mode output signal may be used as feedback so that the left and right channel output signals so that these signals are dependent upon feedback from the common mode output signal. The quasi-differential power amplifier may include a first amplifier driving the left channel output signal, a second amplifier driving the right channel output signal, and a third amplifier driving the common mode output signal. In one application, the quasi-differential amplifier may be used to drive three-wire stereo headphones for use in small portable stereo systems.

Abstract: A first selector switch outputs a second audio signal of m channel corresponding to a selected second zone to a power amplifier of the m channel and a second selector switch couples output of the power amplifier of the m channel to a speaker terminal for the selected second zone whereby an audio signal can be supplied to either one of a plurality of second zones. In one aspect of the invention, a first selector switch outputs a second audio signal of m channel corresponding to a selected second zone to a power amplifier of the m channel determined by a control section and a second selector switch couples output of the m channel determined by the control section to a speaker terminal for the selected second zone whereby an audio signal can be supplied to one or more zones among plural second zones.

Abstract: The active HVAC duct element can be inserted into a HVAC duct for attenuation of noise. The element works with an acoustical series arrangement of a passive acoustical component and an active acoustical component.

Abstract: An electronic stethoscope having a vibration transducer, an amplifier, a headphone arrangement, and at least one digital filter for establishing at least one impulse transfer function corresponding to at least one acoustic stethoscope type. Thus, the signals heard will correspond to those learned, and thereby the advantages of greater amplification and elimination of noise sources may be fully utilized. The ability to compensate for an individual doctor's hearing loss is enabled. Furthermore, with stereoscopic embodiments, sound frequency distributions can be transformed to spatial or temporal sound distributions perceivable by the user facilitating, for example, the detection of heart murmurs and the taking of blood pressure.

Abstract: A portable audio device includes an audio signal generating device for generating an audio signal, a body/motion signal detecting device for detecting and generating a body/motion signal, a signal loop selecting circuit which is coupled to the body/motion signal detecting device, a timer control circuit which generates a loop selection controlling signal at a predetermined time interval, a control device and an audio signal output device which outputs the audio signal vocally. The audio signal generated by the audio signal output device is transmitted to the audio signal output device, and the body signal is transmitted to the audio signal output device under control of the loop selection controlling signal generated by the timer control circuit at the predetermined time interval.