Abstract: An active noise elimination electronic system is disclosed. The electronic system includes a housing, a first electronic device, a noise receiver, an error sensor, a sound actuator, and a microprocessor. The first electronic device is arranged in the housing. The noise receiver is arranged in the housing and is close to the first electronic device for collecting first noise generated by the first electronic device. The error sensor is arranged in the housing for collecting a feedback noise which is different from the first noise. The microprocessor is coupled to the noise receiver, the error sensor and the sound actuator, and controls the sound actuator to produce a second noise which phase is inverse the first noise according to the first noise and the feedback noise.

Abstract: A sound device includes an input terminal for electronic signal input; a line out terminal adapted to output electronic signals input on the input terminal to an external area; a delay arrangement adapted to delay electronic signals input on the input terminal for a certain time; a main output arrangement adapted to output electronic signals delayed by the delay arrangement. The delay arrangement delays signals in order to accommodate a time difference between (1) electronic signals output from an external sound device connected with the line output terminal and (2) electronic signals output from the main output arrangement. The time difference between sound that is output from the sound device and the one that is output from an external sound device that is connected with line connection terminal can be eliminated. Thus, it can prevent sound quality decrease due to time difference from happening.

Abstract: A noise control system is operable within a box-like structure provided by the dual bulkhead plenum of the vehicle dashboard positioned within the transfer path along which the noise is being transmitted from the source of the generated noise to the receiver of the noise in the passenger compartment of an automobile. The plenum is divided into discrete chambers into each of which is provided a counter noise generating apparatus to create a counteracting noise offsetting the noise generated at the source. The acoustic resonance of the chambers amplifies the noise control energy. The geometry of the individual chambers can be varied to optimize the packaging and sound control or shaping strategy. The sound energy permitted to pass through the plenum to the driver's side of the passenger compartment can be tuned to be different than the noise received in the passenger's side.

Abstract: The filter coefficients of an adaptive notch filter are sequentially updated to minimize an error signal based on the error signal and a first reference signal which is produced by subtracting a signal which represents the product of a sine corrective value C1 and a reference sine signal, from a signal which represents the product of a cosine corrective value C0 and a reference cosine signal. The filter coefficients of an adaptive notch filter are sequentially updated to minimize the error signal based on the error signal and a second reference signal which is produced by adding a signal which represents the product of the reference sine signal and the cosine corrective value C0 and a signal which represents the product of the reference cosine signal and the sine corrective value C1 to each other.

Abstract: An active sound muffler for reducing a sound to be reduced as emitted from a sound source located at one of the opposite sides of a sound insulating wall and diffracted and transmitted to the other side, the muffler comprises a control loudspeaker arranged at the front end or the other side of the sound insulating wall and adapted to output a control sound with a predetermined amplitude and a predetermined phase, a control microphone arranged above the sound insulating wall and adapted to gauge the sound pressure or the acoustic intensity of the sound to be reduced and that of the control sound and a control circuit for controlling the output of the control loudspeaker so as to minimize the sound pressure or the acoustic intensity, whichever appropriate, based on the outcome of gauging of the control microphone, and the control loudspeaker showing a line sound source characteristic.

Abstract: A method for noninvasive on-line secondary path modeling for the filtered-X LMS algorithm actively controls periodic noise. The method, based in the frequency domain, uses the concept of linear independence of two equations/two unknowns to arrive at the secondary path estimate. Linear independence of the two equations is achieved by adjusting the control filter output via the filter coefficients prior to the acquisition of the second set of data corresponding to the second equation.

Abstract: An active noise control system is provided which cancels a noise using a sound radiated from a speaker driven by an output from an adaptive notch filter. The system employs output signals from an adder or simulation cosine-wave and sine-wave signals, an error signal or an output signal from a microphone, and a compensated signal from the adder or a signal available for acoustically transferring an output from the adaptive notch filter to the microphone in accordance with initial transfer characteristics to update the filter coefficient of the adaptive notch filter. This configuration allows the system to operate with stability even when the acoustic transfer characteristics vary with time or under circumstances where there exists a significant amount of incoming external noises. The system also prevents overcompensation for a noise at the ears of a passenger in a vehicle, thereby proving an ideal noise reduction effect.

Abstract: An active noise control system is provided which cancels a noise using a secondary noise from a speaker that is operated in accordance with an output from an adaptive controller. The system is configured such that microphone monitor interrupts a switch to thereby stop the secondary noise from being produced, when an error signal delivered by a microphone used for an adaptive computation in an LMS processing portion has the same sign for a predetermined duration. This allows the system to prevent the user from hearing an abnormal acoustic noise resulting from an abnormal operation or divergence of an adaptive filter even when the output signal from the microphone used for the adaptive computation is indicative of an abnormal level.

Abstract: A system for monitoring the use of a hearing protection unit comprising a left ear hearing protection device (14) and a right ear hearing protection device (12) to be worn by a user (10) within a monitoring area, an arrangement (16, 18, 22, 1006, 2006) for wirelessly detecting the position of the left ear hearing protection device (14) and the position of the right ear hearing protection device (12) within the monitoring area, a device (22) for judging whether a predefined condition for the detected positions of the left ear hearing protection device and the right ear hearing protection device is fulfilled, and a device (22) for outputting a wearing compliance signal depending on whether the predefined condition is found to be fulfilled by the judging device or not.

Abstract: An active acoustic noise reduction system which comprises a single input transducer and an output actuator that are physically located next to each other in the same location. In one embodiment, the input transducer and the output actuator are a hybrid represented by a single element. The active noise reduction system is located as close as possible to the noise source and functions to generate an antinoise cancellation sound wave with minimum delay and opposite phase with respect to the noise source. The noise reduction system also comprises a non linearity correction circuit, a delayed cancellation circuit and variable gain amplifier. The system provides user control of the quiet zones generated by the system by varying the gain of the variable gain amplifier. The system provides a user with the ability In one embodiment, an echo canceler is utilized to remove echoes fed back from the output actuator.

Abstract: A system and method for actively damping boom noise within an enclosure such as an automobile cabin. The system comprises an acoustic wave sensor, a motion sensor, an acoustic wave actuator, a first electronic feedback loop, and a second electronic feedback loop. The enclosure defines a plurality of low-frequency acoustic modes that can be induced/excited by the enclosure cavity, by the structural vibration of a panel of the enclosure, by idle engine firings, and a combination thereof. The acoustic wave actuator is substantially collocated with the acoustic wave sensor within the enclosure. The motion sensor can be secured to a panel of the enclosure.

Abstract: A multi-channel active noise control system and method of reducing tonal noise emanating from a tonal noise source are disclosed. The system may include an adaptive controller, a plurality of loudspeakers driven by the loudspeaker, one or more microphones for generating one or more error signals to feedback to the adaptive controller and optionally a reference signal source to provide the adaptive controller with frequency information associated with the tonal noise source. The system and method of the present invention are applicable to any tonal noise source, including but not limited to axial fans.

Abstract: A noise or vibration control system reduces a sampling rate and reduces a control rate to improve computation efficiency. The present invention permits the use of a sample frequency (fs) that is less than twice the frequency of interest (fd). The sensed signals are filtered to extract a particular frequency range with a lower bound given by (2n?1)*fs/2 and an upper bound given by (2n+1)*fs/2, where n is an integer chosen so that the frequency of interest (fd) is within the extracted frequency range. The control commands are also calculated at a reduced rate, which is dependent upon the bandwidth of the tone, rather than the absolute frequency of the tone. Rather than updating the control signals directly on the sampled sensor data yk as it enters the computer, the control computations are done on the harmonic components ak and bk, or equivalently on the magnitude and phase.

Abstract: A system and method reduces undesired noise or vibration in a vehicle. The ambient vibration is measured and command signals are generated over time. The command signals are generated based upon the measured vibration and based upon a control weighting. By varying the control weighting over time, the maximum possible performance is always obtained subject to the saturation constraints.

Abstract: An active noise control system (100) and method compensates for changes in a microphone output to maintain accurate noise control. A calibration signal reflecting a desired microphone output is generated and stored in an active noise control module (106). During operation, the active noise control module (106) compares an actual microphone output signal with the calibration signal and compensates for any changes in the actual output signal before any noise compensation or cancellation function occurs.

Abstract: An adaptive noise canceling system for extracting a desired signal, comprising an adaptive noise cancellation filtering circuit for suppressing noise from a first input signal using a second input signal as a reference signal, and generating an output filtered signal representing the desired signal; and an adaptive noise cancellation controller for receiving the first and second input signals and the output filtered signal, and generating an output control signal for controlling coefficients of at least one adaptive filter of the adaptive noise cancellation filtering circuit, comprising a silence detector unit for detecting whether an acoustical signal is present in the input signals and the output filtered signal, and generating a first output signal which indicates whether the acoustical signal is present; a signal detector unit for detecting whether the desired signal is present in the input signals and the output filtered signal, and generating a second output signal which indicates whether the desired si

Abstract: An active noise control system includes a source unit for generating regenerative signals, an ANC unit for processing signals so as to actively cancel noise, sensors for detecting the information on the inside and outside of a vehicle, a vehicle interior voice discriminating unit for discriminating voice of conversation generated in the vehicle interior, an amplifier for amplifying the signals processed by ANC unit and reproducing transducers for reproducing the signals amplified by the amplifier.

Abstract: A phase-locked loop (PLL) circuit generates a sine wave signal synchronized with an input signal. The sine wave signal is directly supplied to a first multiplier. The sine wave signal is also supplied to a second multiplier after shifting the phase by 90 degrees by an all-pass filter (APF). The first and second multipliers multiply the corresponding input signals by corresponding predetermined gains. An adder sums the products. Sound corresponding to the sum is produced from a speaker to a sound field. A filter-controlling unit controls the gains for the first and second multipliers, respectively, to minimize an error signal “e” for the output level of a microphone installed at a listening position.

Abstract: A noise reduction apparatus is capable of suppressing deterioration of an aural sensing level due to noise existing in a sound field. The apparatus synthesizes a signal obtained by adding a predetermined delay to a sound field noise and reversing and amplifying the signal with an electric signal from a sound reproduction system to obtain a sound pressure output by using a first signal processing part. On the other hand, the apparatus synthesizes a signal obtained by delaying an electric signal from the sound reproduction system by a predetermined period and reversing and amplifying the signal with an electric signal obtained from a sound pressure in the proximity of a concha of a listener to extract a residual noise component by using a second signal processing part. The apparatus controls the delay amounts and the gains set by the first and second signal processing parts so as to minimize an extraction signal.

Abstract: Method for controlling a control arrangement controlling a predetermined system (10), the control arrangement comprising a controller (6), M output sensors (4) providing an output signal vector y(t), L control actuators (2) controlled by a control signal vector u(t) provided by the controller (6) and N reference signal generators (8) for providing a reference signal vector z(t) to the controller (6). The method comprises the step of minimizing a criterion function J defined as a mixture of energy of an observed output signal vector &egr;1(t) and energy of a control error signal vector &egr;2(t), by recursively updating the controller coefficients in w(t) proportional to the observed output signal vector &egr;1 and proportional to the control error signal vector &egr;2.

Abstract: The filter coefficients of an adaptive notch filter are sequentially updated to minimize an error signal based on the error signal and a first reference signal which is produced by subtracting a signal which represents the product of a sine corrective value C1 and a reference sine signal, from a signal which represents the product of a cosine corrective value C0 and a reference cosine signal. The filter coefficients of an adaptive notch filter are sequentially updated to minimize the error signal based on the error signal and a second reference signal which is produced by adding a signal which represents the product of the reference sine signal and the cosine corrective value C0 and a signal which represents the product of the reference cosine signal and the sine corrective value C1 to each other.

Abstract: A noise shaping system including an inner loop and outer noise shaping loops. The inner noise shaping loop includes an inner loop filter and a quantizer for quantizing an output of the inner loop filter. The outer noise shaping loop includes an outer loop filter having an input receiving feedback from the quantizer of the inner noise shaping loop and an output driving an input of the inner loop filter of the inner noise shaping loop.

Abstract: A circuit for blocking reception of in-band frequency-shift keyed (FSK) signals by the reception transducer of a telephone subscriber terminal without requiring muting of the reception transducer. The incoming telephone reception signal, which contains both voice and frequency-shift keyed (FSK) signal components, is processed, e.g., within a digital signal processor (DSP), such that the FSK signal component is substantially cancelled. The incoming telephone reception signal is processed to extract amplitude, frequency and phase information, as well as to recover the FSK data clock. This FSK signal information is then used to generate a replica FSK signal for summing with the incoming telephone reception signal to cancel the FSK signal component.

Abstract: A thin, lightweight electroacoustic actuator device covering a large surface area providing a high piston-like output over the frequency range of from at least 30 to in excess of 500 Hz comprising a stiff, lightweight face plate; a backing structure disposed below the face plate; at least one driver structure disposed between the face plate and the backing structure; and flexible structure flexibly connecting the at least one driver to the face plate.

Abstract: A method for controlling induction sound of an internal combustion engine is described. The method includes computing a first sound pressure during a run up of the engine, wherein the first sound pressure is based on each order of sound generated by the engine. Next, the engine is operated engine under a plurality of operating conditions and a second sound pressure is computed for each of the operating conditions. A frequency response of a microphone and a speaker used in computing the first and second sound pressures is then determined. The method further includes obtaining current vehicle operating conditions and decomposing the first and second sound pressures and the frequency response into engine orders. A net control signal is then generated, wherein the signal is based on each of the first and second sound pressures, the frequency response and the vehicle operating conditions so as to independently control individual orders of the engine sound.

Abstract: A noise or vibration control system improves the quality of adaptation estimates by filtering the input signals to the adaptation, selectively implementing a “dead-zone” during which adaptation does not occur and by selectively adding a dither signal to the control commands. The dead-zone is based on the magnitude of the changes in the control commands, which are responding to the changes in the sensor signals. The dead-zone can be applied to all actuators simultaneously, or can be applied to the adaptation of each actuator channel independently. To maintain identifiability, a “dither signal” is added to the control commands to “ping” the system to increase the amount of information available to the adaptive algorithm. The dither signal is preferably implemented on only one actuator channel at a time. Also, the dither amplitude for each channel is preferably set to be proportional to the current control amplitude.

Abstract: A method of canceling echoes in a telecommunications system wherein an exchange of information takes place between a local subscriber and a subscriber at the remote end of a transmission link and at least one subscriber is assigned an echo canceller, the parameters of which are set as a function of an echo delay time (i). The signs of the signal x(t) transmitted by a subscriber and the signal y(t) received by the subscriber can be determined at equidistant time intervals (Ti) so that sign sequences arise which are stored and compared with one another, and in the event of a direct correspondence or a correspondence as a result of an inversion of the sign sequences of the received signal y(t) and of the transmitted signal x(t) the received signal y(t) is detected as an echo and the echo delay time (i) is calculated.

Abstract: A method for noninvasive on-line secondary path modeling for the filtered-X LMS algorithm actively controls periodic noise. The method, based in the frequency domain, uses the concept of linear independence of two equations/two unknowns to arrive at the secondary path estimate. Linear independence of the two equations is achieved by adjusting the control filter output via the filter coefficients prior to the acquisition of the second set of data corresponding to the second equation.

Abstract: An active noise control system (100) increases system stability by modifying a spectral shaping path (112) to prevent unbounded growth in the system error. In one embodiment, a model of the physical path (114) within the spectral shaping path (112) is given a positive bias, encouraging the model to overestimate the actual characteristics of the physical path (114). In another embodiment, the gain in the spectral shaping path (112) is normalized so that the gain decreases as the system output increases, placing an upper bound on the output signal. By modifying the model or the gain in the spectral shaping path (112), the invention improves system stability by limiting the destabilizing effects of modeling errors on the system.

Abstract: An active noise control apparatus for transmitting, from a loud speaker, a secondary noise synthesized so as to have the same amplitude as and the opposite phase to a primary noise and for canceling the noise by acoustically overlapping the secondary noise. An overall system filter for simulating a characteristic of an overall system leading to an error detecting microphone from a noise detecting microphone is provided for the first and the second overall system filter. A second and a first noise control filter are connected to the first and the second overall system filter in cascade to form a noise control filter. A coefficient of an estimating noise transfer system filter, obtained when the difference between the differential output of both obtained when a white noise is applied to the circuit of cascade connections and the response difference of the first and the second overall system filter from a differential overall system filter becomes a minimum, is made the coefficient of the noise control filter.

Abstract: An adaptive feedback control system (7) has a feedback loop (8) and a digital adaptive compensation filter (10). An auxiliary noise signal (30) is added to a reference signal (26) for use in residual-loop gain identification. A residual-loop gain identifier uses the noise signal (30) and a signal taken from the output of the compensation filter (29) to determine the residual-loop gain transfer function of the system. Once the residual-loop gain has been determined, the filter coefficients from the identifier are copied to an open-loop gain adaptor (18). The actual open-loop gain transfer function of the system is compared to a reference open-loop gain transfer function. The compensation filter (10) is adapted so that the desired open-loop gain transfer function for the system is achieved.

Abstract: System for producing a substantially noise-free signal of an acoustic sound, and for producing a sound, the sound including a desired sound and an anti-phase noise sound, the anti-phase noise sound being in anti-phase relative to a noise, the system including an acoustoelectric transducer, a reference-acoustoelectric transducer and an audio controller coupled with the reference-acoustoelectric transducer and the acoustoelectric transducer, wherein the acoustoelectric transducer produces a noise bearing sound signal by detecting the acoustic sound and the noise, wherein the reference-acoustoelectric transducer produces the reference noise signal by detecting the noise in a noisy environment and wherein the audio controller produces the substantially noise-free signal, according to the reference noise signal and the noise bearing sound signal.

Abstract: Voice Activity Detection (VAD) devices, systems and methods are described for use with signal processing systems to denoise acoustic signals. Components of a signal processing system and/or VAD system receive acoustic signals and voice activity signals. Control signals are automatically generated from data of the voice activity signals. Components of the signal processing system and/or VAD system use the control signals to automatically select a denoising method appropriate to data of frequency subbands of the acoustic signals. The selected denoising method is applied to the acoustic signals to generate denoised acoustic signals.

Abstract: A system for identifying a model of an acoustic system in the presence of an external noise signal is disclosed. The system includes an acoustic actuator for generating controlled sound within the acoustic system. A sensor receives the controlled sound and the external noise signal and produces a sensed signal. A control system generates a control signal in response to an error signal. The control system includes a system model for generating an estimated response signal. The control system also generates the error signal representing the difference between the sensed signal and the estimated response signal. A masking threshold generator receives the sensed signal and the error signal and produces spectral shaping parameters. A shaped signal generator for receives the spectral shaping parameters and produces a test signal which is provided as an input to the control system.

Abstract: A method and system for removing acoustic noise removal from human speech is described. Acoustic noise is removed regardless of noise type, amplitude, or orientation. The system includes a processor coupled among microphones and a voice activation detection (“VAD”) element. The processor executes denoising algorithms that generate transfer functions. The processor receives acoustic data from the microphones and data from the VAD. The processor generates various transfer functions when the VAD indicates voicing activity and when the VAD indicates no voicing activity. The transfer functions are used to generate a denoised data stream.

Abstract: An adaptive signal processing system for improving a quality of a signal. The system includes an analysis filterbank for transforming a primary information signal in time domain into oversampled sub-band primary signals in frequency domain and an analysis filterbank for transforming a reference signal in time domain into oversampled sub-band reference signals. Sub-band processing circuits process the signals output from the filterbanks to improve a quality of an output signal. A synthesis filterbank can combine the outputs of the sub-band processing circuits to generate the output signal.

Abstract: In an active noise control method of the present invention, a noise detection signal from a noise referring microphone which detects ambient noise is inputted into noise processing units of different types to produce noise silencing signals. A selected noise silencing signal is inputted into a receiver or a speaker together with a reception signal via an adder, so that a regenerated tone from the noise silencing signal silences the ambient noise, When a nonconformance detecting unit judges that the selected noise silencing signal exceeds a predetermined range, the corresponding noise processing unit is judged to be incompatible, and a switch control unit controls a switch to select another one of the noise processing units.

Abstract: A system and method for actively damping boom noise within an enclosure such as an automobile cabin. The system comprises an acoustic wave sensor, a motion sensor, an acoustic wave actuator, a first electronic feedback loop, and a second electronic feedback loop. The enclosure defines a plurality of low-frequency acoustic modes that can be induced/excited by the enclosure cavity, by the structural vibration of a panel of the enclosure, by idle engine firings, and a combination thereof. The acoustic wave actuator is substantially collocated with the acoustic wave sensor within the enclosure. The motion sensor can be secured to a panel of the enclosure.

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 device generates a directional anti-sound beam by modulating an ultrasonic carrier with a sound canceling signal and exciting an ultrasonic transducer with the modulated signal. When the anti-sound beam is directed at a sound source, the level of sound from the sound source is reduced. A microphone monitors the resultant sound for adjusting the sound canceling signal. An alternate signal may be further modulated upon the anti-sound beam to provide a substitute sound at the sound source.

Abstract: A speakerphone incorporates a portion defining a loudspeaker cavity, the cavity containing a loudspeaker. The speakerphone also includes a handset with an internal microphone in the handset. The speakerphone has a housing adapted to receive the handset, and when it is thus received, the handset microphone is acoustically coupled to the loudspeaker cavity, allowing the handset microphone signal to be used to control feed-back or feed-forward algorithms that enhance the performance of the speakerphone.

Abstract: A noise control system includes: a control sound generator for generating a control sound; an error detector for detecting an error signal between the control sound and noise; a noise detector for detecting a noise source signal; an adaptive filter for outputting a control signal; and a coefficient updator for updating a coefficient of the adaptive filter. The coefficient updator includes at least a first digital filter, a first coefficient update calculator, a second digital filter, a phase inverter, a third digital filter, and a second coefficient update calculator. Alternatively, the coefficient updator includes at least a first digital filter, a second digital filter, a third digital filter, a coefficient update calculator, a phase inverter, a first adder, and a second adder. In either case, the coefficient updator has a function of suppressing an increase in a coefficient gain of the adaptive filter in a predetermined frequency band.

Abstract: An active noise controller includes a duct (2) of a stainless steel having the shape of a pipe and provided with an opening (1) at a first end thereof, and a loudspeaker (3)connected to a second end of the duct (2). The duct (2) is disposed with its opening (1) located at a distance not greater than half the wavelength of a sound produced by a sound source (4) from the sound source (4) so as to face the sound source (4). A sound produced by the vibration of the vibrating member (5) of the loudspeaker (3) travels from the second end of the duct (2) through the duct (2) to the first end of the same, and the sound is radiated toward the sound source (4). The sound radiated through the opening (1) has a frequency substantially equal to that of an unnecessary sound included in the sound produced by the sound source (4), an amplitude substantially equal to that of the unnecessary sound and a phase substantially opposite to that of the unnecessary sound.

Abstract: An active noise control system is provided to specify an input transducer, an error transducer, an output transducer and an active noise controller for generating an anti-phase canceling acoustic signal to attenuate an input noise and to output a reduced noise. The active noise control system also performs on-line secondary path modeling. For this purpose the active noise control system comprises, in addition to known systems, a secondary path change detection circuitry (6), a signal distinguishing circuitry (7) and an auxiliary noise control circuitry (8), all of them being used to model said secondary path. FIG.

Abstract: Pseudo space transmitting signal processing means of the signal processing means simulates the frequency response of the space up to the silencing point from a noise source, while pseudo inverse filter signal processing means simulates an inverse filter characteristic 1/(K×Sp×G1) for canceling the characteristic of the combined frequency response (K×Sp×G1) of K of noise input means, Sp of a secondary sound source speaker, and G1 up to a silencing point from a secondary sound source speaker. The pseudo space transmitting signal processing means and pseudo inverse filter signal processing means set a gain characteristic equal to an original space transmitting characteristic and inverse filter characteristic, respectively.

Abstract: An active noise reduction system is provided having a novel configuration that uses a fixed point digital filter to estimate an inverted replica of the acoustic noise from the measurement of the control error at some predefined position. The inverted replica of the measured acoustic noise is used to generate an accurate acoustic control response that is processed by a fixed point digital filter in order to compensate for the undesirable dynamic effect of the physical components comprising the system. The system in effect yields a configuration that is open loop and which can provide an acoustic control response with an ability to generate a close match of the inverted replica of the acoustic noise. The system is not constrained by closed loop stability concerns which occur when employing an analogue feedback compensation approach. Nor is the configuration of the present invention hindered by poor parameter convergence as in the case of an adaptive feedforward implementation.

Abstract: An adaptive passive acoustic attenuation system implements control techniques to facilitate practical use of adaptive passive acoustic attenuation in industrial and commercial applications. The system includes multiple banks of multiple adjustable tuners that are used to passively attenuate an acoustic disturbance (e.g. a tone) propagating through an acoustic plant. All of the tuners in one of the banks are contemporaneously adjusted during an adaptation scan while the tuners in the other banks remain stationary. The process is then carried out for the other banks of adjustable tuners. The number of adjustable tuners per bank is chosen so that adaptation scans of the tuners in the respective bank create observable changes in acoustic levels to enable adaptation. Multiple sets of multiple banks of adjustable tuners can be provided to attenuate multiple disturbances propagating through the acoustic plant.

Abstract: An apparatus for reducing noise emitted by an electronic or other device and such devices incorporating the noise reducing apparatus. A mechanism for acoustically filtering undesired noise from an electronic device, particularly noise generated by a cooling mechanism is disclosed. In a preferred embodiment, noise is filtered at least in part with an appropriately dimensioned compressible air space. The noise reducing or filtering mechanism may be utilized with portable and non-portable computers, stereos, entertainment equipment and other devices.

Abstract: An extracting assembly for extracting a component signal generated by a component source from a composite signal is disclosed wherein a reference sensor generates a reference signal relating to activity of the component source, a composite sensor senses the composite signal, an adaptive filter is operatively connected to the reference sensor and the composite sensor to filter the component signal from the composite signal as a function of the reference signal generated by the reference sensor, and a normalizer operatively connected to the adaptive filter for normalizing the step size of each iteration taken by the adaptive filter to minimize the time to adapt the adaptive filter to transform the reference signal into the component signal.

Abstract: An off-line modeling system (50) is provided for modeling a feedback path by calculating filter taps. The off-line modeling system (50) includes a reference sensor (16), a secondary source (18), and an off-line modeling circuitry (10). The reference sensor (16) receives a noise signal and a feedback signal (22) and generates a primary signal x(n) in response. The secondary source (18) receives a modeling signal v(n) and provides the modeling signal v(n) to the feedback path. The off-line modeling circuitry (10) includes a signal discrimination circuitry (54), a modeling signal generator (64), a feedback path modeling adaptive filter (60), and associated adaptive algorithm (62) and a summing junction (58). The signal discrimination circuitry (54) receives the primary signal x(n) and generates a modified modeling signal v′(n). The modeling signal generator (64) generates the modeling signal v(n).