Abstract: There are provided a method and an apparatus for reducing random, continuous, non-stationary noise in audio signals, the noisy audio signal being filtered by means of a predetermined filter function. The filter function is determined dynamically having regard to the current properties of the noisy audio signal and/or its constituent parts, and the filter function is also limited dynamically having regard to the current properties of the noise component contained in the noisy audio signal.

Abstract: A signal filter includes a first adaptive filter receiving a desired signal containing a noise component and a first noise correlated reference signal, and outputting a first filtered output signal. A second adaptive filter, receives the desired signal containing the noise component and a second noise correlated reference signal and outputs a second filtered output signal. Signal filter parameters of the second adaptive filter are controlled based on the first filtered output signal and the second filtered output signal.

Abstract: A circuit arrangement for controlling audio signal transmissions for a communications system that includes a microphone and a video camera. The arrangement comprises a video processor configured and arranged to receive a video signal from the video camera, detect movement of an object in the video signal, and provide a motion-indicating signal indicating movement relative to the object. An audio processor is coupled to the video processor and is configured and arranged to modify the audio signal to be transmitted responsive to the motion-indicating signal. In another embodiment, a video signal processor is configured and arranged to receive a video signal from the video camera, detect mouth movement of a person and provide a mouth-movement signal indicative of movement of the person's mouth.

Abstract: A filtering device consisting of a nonadaptive feedback filter that generates active attenuation of the vibration on the framework, without generating instability in a first frequency band, and an adaptive feedforward filter is disclosed. Feedforward filtering coefficients are adapted in real time according to an algorithm chosen to minimize the energy of the types of vibration which are picked up by a sensing device as a function of the energy of the types of vibration which are picked up by the sensing device, and of the previously measured transfer function, in the presence of a feedback filtering device and in the absence of a feedforward filtering device, between an actuator device and a first sensing device. The device makes it possible to linearize the feedback attenuation throughout a second frequency band which is wider than the first frequency band, to accelerate the convergence of the minimization algorithm and to enhance the robustness of the feedforward filter.

Abstract: The present invention considers a method for active cancellation using independent component analysis. More particularly, the present invention relates to a method which is operable the independent component analysis technique to an adaptive algorithm that can consider secondary or more higher statistical characteristics.

Abstract: A digital hearing aid uses a digital filter using coefficient multipliers and with digital signal processing algorithms, which can be implemented with a minimum amount of dedicated circuitry, which may be contained in an integrated circuit. Power consumption in the digital hearing aid is kept to a minimum by the use of a single, general purpose multiplier by eliminating a multiplexed multiplier, and by eliminating a plurality of general purpose multipliers. Preferably, filter coefficients which are limited to powers of 2 are used in the digital filter, whereby coefficient multipliers function as shifters. Shifting-hardware is simpler and more economical compared to a multiplier. Multiplication by powers of 2 is implemented by circuit connections in the hearing aid circuitry, without requiring any power expenditure from the battery. The digital filter may be a non-recursive finite impulse response (FIR) digital filter, or, an infinite impulse response (IIR) digital filter.

Abstract: A system for enhancing vibration reduction in a vehicle that utilizes one or more sensors which sense ambient vibration in the vehicle and generate a signal corresponding to the sensed vibrations. A control circuit is coupled to the sensors and receives the signals. The control circuit, utilizing Kalman filtering algorithms, generates a control signal that adapts a previous command force, from an actuator to a sensor, thereby dynamically updating a parameter that represents an estimated vehicle response. This dynamically updated parameter is a result of utilizing a covariance that is a function of an empirically derived constant value and a change in forces exerted by the actuator. The control circuit outputs this control signal to vibration generator units, which generate a vibration field for reducing vibrations in the vehicle.

Abstract: A method and system for attenuating the effects of unknown, unmeasurable and time-varying exogenous disturbances on multiple-input multiple-output dynamical systems are described. The disturbance rejection system is characterized in terms of an ARMARKOV or predictive model controller. The parameters of this controller are revised in real time at discrete time steps so as to generate an input to the dynamical system that attenuates the effect of the exogenous disturbance on any chosen set of measured outputs of the dynamical system. The method for revising the controller parameters involves the steps of defining a novel retrospective cost function based on windows of past data, calculating a gradient that is based on this cost function, and using an implementable adaptive step size that brings the controller parameters closer to optimal controller parameters after each revision.

Abstract: Public announcements are made in a space using n speakers after having determined the impulse response hij(t) between a plurality of calibration points j belonging to the space and each speaker i. To transmit an information-bearing acoustic signal S(t) through at least one target area in the space in which announcements are to be made, each speaker i is made to transmit a signal (a), where j is an index representing calibration points in the target area.