564 results about "Active noise control" patented technology

The technology of active noise reduction (ANR) is incorporated into audiometry testing in a variety of formats. Analog feedback, digital feedback, adaptive feedforward, and adaptive feedback noise control schemes are presented for use in audiometry to reduce the ambient noise heard by the test subject, allowing subject testing in higher ambient noise fields. Audiometer test signals are appropriately compensated so the test results are accurate and comply with existing calibration standards for audiometers. Existing audiometry headphone technologies are modified so that ANR can be accomplished while satisfying existing standards for audiometric testing. Embodiments are also defined for alternate headphone arrangements that may not conform to current (1997) audiometric testing standards but provide sufficient performance advantages to warrant new standards for audiometry testing in the future.

An active noise cancellation system reduces, at a listening position, the power of a noise signal being radiated from a noise source to the listening position. The system includes an adaptive filter that receives a reference signal representing the noise signal, and provides a compensation signal. A bass management unit receives the compensation signal and applies a phase shift to the compensation signal to provide a phase shifted compensation signal. A first acoustic radiator receives the phase shifted compensation signal and radiates audio indicative thereof to the listening position. A second acoustic radiator receives the compensation signal and radiates audio indicative thereof to the listening position. The transfer function characteristics from the input of the bass management system to the listening position approximately matches a desired transfer function.

An active noise control (ANC) system may be implemented to both sides of a fan, such that both directions of the noise emitting are treated to reduce the overall noise. The impact on airflow is minimal, and the technique is very effective in a broad range of low frequencies. Passive sound-absorbing materials may be included for attenuation of high frequencies. The resulting quiet fan produces a low level of noise compared to any other device based on fan, which produces the same capacity of airflow. The quiet fan may be incorporated in any mechanical system which requires airflow induction such as: computers, air conditioners, machines, and more.

A system for actively reducing noise at a listening point, includes an earphone housing, a transmitting transducer, a receiving transducer and a controller. The transmitting transducer converts a first electric signal into a first acoustic signal, and radiates the first acoustic signal along a first acoustic path having a first transfer characteristic and along a second acoustic path having a second transfer characteristic. The receiving transducer converts the first acoustic signal and ambient noise into a second electrical signal. The controller compensates for the ambient noise by providing a noise reducing electrical signal to the transmitting transducer. The noise reducing electrical signal is derived from a filtered electrical signal that is provided by filtering the second electrical signal with a third transfer characteristic. The second and the third transfer characteristics together model the first transfer characteristic.

A feedback active noise cancellation headphone is disclosed. A plurality of microphone sensors are disposed in front of the left and the right speakers of the headphone for improving the sound reception quality of the microphone sensors, so that the active noise controlling circuit generates an inverse phase soundwave accurately for countering the low frequency noise, and further to improve the noise reduction performance of the active noise cancellation headphone.

An active noise/vibration/sound control system for a vehicle has an ANC (active noise control apparatus), an AVC (active vibration control apparatus), and an ASC (active sound control apparatus). To prevent the ANC, the AVC, and the ASC from interfering with each other and hence to prevent vehicle cabin environment of vibrations, noise, and sound from being impaired, activation and inactivation of the ANC, the AVC, and the ASC are controlled or their control characteristics are controlled in relation to each other by a weighting variable calculator as a coordination controller, depending on an engine rotation frequency and a frequency change which are representative of a running state of the vehicle as detected by an engine rotation frequency detector and a frequency change detector that serve as a running state detector.

A subtractor subtracts an echo canceling signal Ĉ·yl(n−1) from a canceling error signal e(n) to estimate a residual noise to be silenced at the position of a microphone, and outputs a first basic signal x1(n) representing the residual noise. A first control circuit section generates a first control signal y1(n) based on the first basic signal x1(n) and a second basic signal x2(n) that is generated by delaying the first basic signal x1(n) by a time Z⁻ⁿ. A second circuit section generates a second control signal y2(n) based on the first basic signal x1(n) and an engine rotation signal.

A close-talk detector detects a near-end user's speech signal, while an adaptive ANC process is running, and in response helps prevent the filter coefficients of an adaptive filter of the ANC process from being corrupted, thereby reducing the risk of the adaptive filters diverge. Upon detecting speech using a vibration sensor signal and one or more microphone signals, the detector asserts a signal that slows down, or even freezes or halts, the adaptation of the adaptive filter. The signal may be de-asserted when no more speech is being detected, thereby allowing the adaptive ANC process to resume its normal rate adaptation of the filter. The detector may continuously operate in this manner during the call, as the user talks and then pauses and then resumes talking. Other embodiments are also described.

An active noise control (ANC) system is configured to generate at least one anti-noise signal configured to drive a speaker to generate sound waves to destructively interfere with an undesired sound present in a target space. The at least one anti-noise signal is adjusted based an output signal of an audio system. The at least one anti-noise signal may be adjusted based on at least one of a volume level of the audio system, a power level of at least one predetermined frequency or frequency range of the output signal of the audio system, frequency content of an output signal of the audio system. The ANC system receives an error signal to adjust generation of the at least one anti-noise signal. The error signal is adjusted to compensate for adjustment of the at least one anti-noise signal based on the output signal of the audio system.

A smart pillow unit and processes for providing active noise cancellation and biofeedback.

The invention discloses a range hood with an active noise reduction function. The range hood comprises a range hood main body and an active noise reduction device fixedly arranged on the range hood main body, wherein the active noise reduction device is provided with a first noise sensor, a loudspeaker, a second noise sensor and an active noise reduction system. Compared with a range hood with a traditional passive noise reduction mode which can only be used for reducing noise above 500 Hz although the leakproofness and material are good, the range hood with the active noise reduction functioncan actively generate reverse sound waves with the same frequency as the outside noise through the active noise reduction device to neutralize the noise so that the noise reduction effect can be achieved. The range hood with the active noise reduction function can enable oil smoke particles to not pass through an air draft assembly, an oil film cannot be attached to a wind wheel in the air draftassembly even with the increase of the use time, load-bearing work is not needed, and therefore low-noise work can be kept all the time. The range hood with the active noise reduction function has theadvantage that the noise of different frequencies can be greatly reduced when the range hood works.

In an active noise reduction apparatus with an adaptive notch filter used, a triangle wave as a reference signal input into a first coefficient updater and a second coefficient updater reduces the number of execution times of product-sum operations in a reference signal generator to reduce the operation load.

A three dimensional area of quiet is created by an active noise cancellation system comprising a reference microphone receiving background noise and sending the noise signal to an adaptive active noise canceller. An adaptive filter system using weights updated by a least mean squares method or other method generates an anti-phase signal which is broadcasted to counteract the background noise. The resulting residual noise or residual signal is sent back to the adaptive active noise canceller to reset the weights of the adaptive filter.

The invention relates to a noise reduction device of a range hood. The noise reduction device is characterized in that a fan inlet is detachably provided with a lower noise-damping device; the lower noise-damping device comprises at least one noise-damping unit; the noise-damping unit comprises a longitudinally arranged noise-damping pipeline; the upper end of the noise-damping pipeline is communicated with the fan inlet, and the lower end of the noise-damping pipeline is communicated with the air outlet of a fume collecting hood; the air inlet end of the noise-damping pipeline is provided with a speaker, the inner wall of the noise-damping pipeline is provided with a reference microphone and an error microphone which is positioned below the reference microphone; and the reference microphone, the error microphone and the speaker are controlled by an active noise reduction controller. The noise reduction device disclosed by the invention can realize the noise reduction without improving the internal structure of the range hood but just by detachably arranging the lower noise-damping device on the fan inlet, the noise-damping device can be assembled and dissembled freely, so that good universality and adaptability are achieved, the problem of noise at the air inlet of the rang hood can be well solved, and the problem of noise of the air outlet of the range hood can be solved by detachably arranging an upper noise-damping device on a fan outlet.

The invention discloses a method and device for counteracting environment noise and an active noise reduction earphone. The device comprises a microphone, a DSP chip, an active noise reduction controller, and a loudspeaker, wherein the microphone is used as a feed-forward noise reduction microphone and an environmental noise monitoring microphone so as to acquire the environmental noise in real time; the DSP chip periodically selects a noise reduction mode best-matched with the current environment according to the environmental noise acquired by the microphone, and sending a corresponding noise reduction parameter to the active noise reduction controller; the active noise reduction controller performs the feed-forward filter noise reduction according to the noise reduction parameter sent by the DSP chip, and outputs the waveform for counteracting the environmental noise; and the loudspeaker plays the corresponding sound signal according to the waveform to counteract the environmental noise at the ear, thereby achieving the optimal noise reduction effect under various different environments, and the switching of the noise reduction mode is self-adaptively performed aiming at different noise environments, thereby guaranteeing that the best noise reduction experience can be provided under various different environments.

A system and method that warn a vehicle driver by shaking or dithering the steering wheel that one or more active control systems on the vehicle is providing active control. The system includes an AFS actuator for providing a steering assist signal for stability control purposes, and a VES actuator for providing resistance against turning of the steering wheel. The system also includes a controller for causing the AFS actuator to shake the steering wheel if the active control is active and for causing the VES controller to apply and release tension to the steering wheel if the steering wheel is turned and the active control is active. The controller may increase the shaking of the steering wheel as the amount of the active control increases.

The invention discloses a voice noise reduction device, which comprises a remote voice noise reduction module and a local voice noise reduction module, wherein the remote voice noise reduction module provides a background noise reference signal for the local voice noise reduction module. The voice noise reduction device realizes the noise elimination of remote voice signals in a voice call by using the active noise reduction and elimination technology-based remote voice noise reduction module and realizes the noise elimination of local voice signals in the voice call by using the noise adaptive-filtering technology-based local voice noise reduction module so as to maximally reduce the interference of background noise to the speech quality of both a caller and a callee in the voice call. Due to the simple structure and easy implementation of the voice noise reduction device, a noise reduction micro earphone comprising a microphone can be realized.

An active noise control apparatus includes a road surface input detector, a reference signal generator, an adaptive filter, a noise-cancellation sound generator, an error detector, a reference signal corrector, a filter coefficient updating unit, a transfer characteristic variation detector, and an update amount controller. The transfer characteristic variation detector is configured to detect a variation in transfer characteristic between the road surface input detector and the error detector. The update amount controller is configured to increase an amount of updating of a filter coefficient to a value greater than a value that is used in a normal mode in accordance with the variation in transfer characteristic detected by the transfer characteristic variation detector.

The invention relates to an active noise reduction system for an engine in an automobile. The system comprises two error microphones, five secondary sound source loudspeakers and one self-adaptation active controller. The two error microphones are arranged at automobile roof positions corresponding to a front row and a back row of the automobile. The five secondary sound source loudspeakers are composed of four vehicle-mounted loudspeaker boxes arranged on the automobile door sides and one secondary sound source arranged at the position of a rear row partition plate. The self-adaptation active controller comprises a DSP master control chip, an audio decoding chip, an off-chip storage unit, a CAN bus controller, a power amplifier, an error microphone signal receiving module, a secondary sound source output module and a power module. The invention further relates to an active noise reduction method for the engine in the automobile. By means of the system and method, error noise signals in active noise reduction reach the minimum value during constant noise reduction control, the noise influence caused by the error noise signals can be basically ignored, and the expected noise reduction effect can be rapidly achieved.

A system is disclosed where the well-known psycho-acoustic masking effect, i.e. frequency and/or temporal masking is applied to reduce the human perception of a noise signal. An input signal, such as music or another entertainment signal, is adjusted based on the intensity of the auditory noise by applying existing knowledge about the properties of the human auditory perception and is provided to the human user as a masking sound signal, so that the masking sound elevates the human auditory perception threshold for at least some of the noise signal, whereby the user's perception of that part of the noise signal is reduced or eliminated. The masking sound may be combined with active noise control where a sound in anti-phase with the noise signal is provided for further reduction of the human perception of the noise signal.

The method of noise attenuation comprises the steps of generating a noise canceling signal, sensing for an system condition, and ceasing the generation of the noise canceling based upon the system condition. This method is embodied in a system that includes an air induction body, a speaker in proximity to the air induction body, a sensor for sensing a system condition, and a control unit with a noise cancellation feature. The control unit is in communication with both the speaker and the sensor. Based upon the sensed system condition, the control unit may disable the noise cancellation feature.

The invention provides a method and device for active noise reduction of a vehicle. The method comprises the following steps: arranging sensors at the positions of noise sources, and collecting real-time noise signal data of each of the noise sources of the vehicle; performing spectral analyses on the real-time noise signal data so as to obtain spectral characteristic information corresponding to each of the noise sources; collecting a noise signal in a driving cabin, and performing the spectral analysis on the noise signal so as to obtain spectral distribution information of noise in the driving cabin; comparing the spectral distribution information with the spectral characteristic information so as to obtain relativity information of the noise in the driving cabin and the noise sources; transmitting a cancellation acoustical signal at a target position in the driving cabin through a loudspeaker according to the relativity information, and enabling waveform cancellation to be formed by the cancellation acoustical signal and the noise of the noise sources. Through the adoption of the method and the device which are disclosed by the invention, the active noise reduction of a driving space and a riding space of the vehicle can be realized.

An active noise control (ANC) system includes at least one infinite impulse response filter (IIR). The IIR filter generates an output signal based on an input signal representative of an undesired sound. The ANC system generates an anti-noise signal based on the output signal of the IIR filter. The anti-noise signal is used to drive a speaker to generate sound waves to destructively interfere with the undesired sound. The ANC system includes an update system to generate update coefficients. The update system determines the stability of the update coefficients. Coefficients of the IIR filter are replaced with the update coefficients. The update system generates a set of update coefficients for each sample of the input signal.