2313results about "Active noise control" patented technology

An active noise cancellation system includes a series of features for more effective cancellation, greater reliability, and improved stability. A particular feature adapted for headset systems includes locating a residual microphone radially offset from the center of a sound generator to detect a signal more similar to that incident upon the eardrum of the user. In addition, an open back headset design includes perforations on the side of the headset instead of the back, so that the perforations are less susceptible to inadvertent blockage. The system also includes a mechanism for detecting changes in the acoustic characteristics of the environment that may be caused, for example, by pressure exerted upon the earpieces, and that may destabilize the cancellation system. The system automatically responds to such changes, for example, by reducing the gain or the frequency response of the system to preserve stability. The system further includes other methods for detecting imminent instability and compensating, such as detecting the onset of signals within enhancement frequencies characteristic of the onset of instability, and adjusting the gain or frequency response of the system or suppressing the enhanced signals. The system further includes a mechanism for conserving battery life by turning the system off when sound levels are low, or adjusting the power supply to the system to correspond to the current power requirements of the system.

An active noise cancellation system that reduces, at a listening position, power of a noise signal radiated from a noise source to the listening position. The system includes an adaptive filter, at least one acoustic actuator and a signal processing device. The adaptive filter receives a reference signal representing the noise signal, and provides a compensation signal. The at least one acoustic actuator radiates the compensation signal to the listening position. The signal processing device evaluates and assesses the stability of the adaptive filter.

Active noise control system and method for controlling an acoustic noise generated by a noise source at a listening location, in which system and method sound is picked up in the surroundings of the listening location by a sound sensor; an electrical noise signal which corresponds to the acoustic noise of the noise source is generated and filtered adaptively in accordance with control signals. The adaptively filtered noise signal is irradiated into the surroundings of the listening location by a sound reproduction device, where a secondary path transfer function extends between the sound reproduction device and sound sensor. The noise signal is filtered with a transfer function that models the secondary path transfer function. The signals which provided by the sound sensor after first filtering serve as control signals for the adaptive filtering.

An adaptive noise canceling microphone system for extracting a desired signal, in particular a desired speech signal, comprising two microphones being arranged at a predefined distance from each other; a signal forming system (SFS) being adapted to receive a first and second input signals resulting from sounds received by the two microphones wherein an acoustical signal component in the first input signal is determined, wherein an acoustical signal component in the second input signal is determined, wherein the acoustical signal component in the first input signal is enhanced to generate a speech enhanced signal, and wherein the acoustical signal component in the second input signal is suppressed to generate a speech nulled signal; an adaptive noise cancellation filtering circuit being adapted to receive the speech enhanced signal and the speech nulled signal, wherein the noise in the speech enhanced signal is cancelled using the speech nulled signal as reference, thereby generating an output filtered signal representing the desired signal.

Apparatus includes generator generating reference signal based on noise emitted from sound source, detector detecting level of reference signal and change in level, unit comparing change with threshold-value range and produce compared result, filter filtering reference signal, adaptive filter having variable filter coefficient, unit updating filter coefficient according to change of level of reference signal for obtaining an updated filter coefficient, unit stopping updating of filter coefficient in response to compared result when change falls outside threshold-value range, unit storing updated filter coefficient each time filter coefficient is updated, generator generating control signal using stored filter coefficient, unit generating control sound based on control signal, microphone detecting synthesis sound pressure of control sound and noise to produce an error signal, and unit setting stored filter coefficient to more accurate coefficient than stored filter coefficient based on error signal, and signal acquired by filtering control signal through filter.

There is provided a noise cancellation system, comprising: an input for a digital signal, the digital signal having a first sample rate; a digital filter, connected to the input to receive the digital signal; a decimator, connected to the input to receive the digital signal and to generate a decimated signal at a second sample rate lower than the first sample rate; and a processor. The processor comprises: an emulation of the digital filter, connected to receive the decimated signal and to generate an emulated filter output; and a control circuit, for generating a control signal on the basis of the emulated filter output. The control signal is applied to the digital filter to control a filter characteristic thereof.

An active noise cancellation system includes an adaptive filter, a signal source, an acoustic actuator, a microphone, a secondary path and an estimation unit. The adaptive filter receives a reference signal representing noise, and provides a compensation signal in response to the received reference signal. The signal source provides a measurement signal. The acoustic actuator radiates the compensation signal and the measurement signal to the listening position. The microphone receives a first signal that is a superposition of the radiated compensation signal, the radiated measurement signal, and the noise signal at the listening position, and provides a microphone signal in response to the received first signal. The secondary path includes a secondary path system that represents a signal transmission path between an output of the adaptive filter and an output of the microphone. The estimation unit estimates a transfer characteristic of the secondary path system in response to the measurement signal and the microphone signal.

An active noise control system generates an anti-noise signal to drive a speaker to produce sound waves to destructively interfere with an undesired sound in a quiet zone. The anti-noise signal is generated with an adaptive filter having filter coefficients. The coefficients of the adaptive filter may be adjusted based on a first filter adjustment from a first listening region, and a second filter adjustment from a second listening region. A first weighting factor may be applied to the first filter adjustment, and a second weighting factor may be applied to the second filter adjustment. The first and second weighting factors may dictate the location and size of the quiet zone as being outside or partially within at least one of the first listening region and the second listening region.

A sound masking system for shaping the ambient noise level in a physical environment. The sound masking system comprises a networked and distributed system having a number of master units coupled together and to a control unit. One or more of the master units may include satellite sound masking units which function to reproduce the sound masking signal generated by the master sound masking unit. Each of the master units is addressable over the network by the control unit enabling the control unit to program the contour, spectral band, and gain characteristics of the sound masking output signal. The system may also include a remote control unit which provides the capability to tune and adjust each master sound masking unit in situ without requiring physical access through the ceiling installation.

A system and method for noise cancellation is disclosed herein generally having at least one microphone, a processor, and a speaker array. The processor may contain an adaptive filtering feature, to separate desirable sound from undesirable sound. The undesirable sound may be suppressed by the processor by creating a canceling waveform and transmitting the canceling waveform to the user's head via a speaker array. The desirable sound may be enhanced by increasing the amplitude of the waveform and transmitting the amplified waveform to the user's head via a speaker array. The sound transmitted to the user's head by the system may be localized using an image tracking subsystem and speaker array. The image tracking system may track the actual visible image or alternatively a heat (e.g. infrared) image of the user's head.

A noise cancellation helmet includes a noise detecting unit which detects noise in a helmet body, a sound outputting unit which outputs a control sound for canceling the detected noise, a control signal generating unit which processes an output signal of the noise detecting unit through computation to generate a control signal for the control sound and applies the control signal to the sound outputting unit, an utterance detecting unit which detects utterance of a wearer, an utterance absent period gain adjusting unit which adjusts a gain of the control signal generating unit in an utterance absent period, an utterance absent period gain storing unit which stores a gain set by the utterance absent period gain adjusting unit immediately before the detection of the utterance, and an utterance present period gain adjusting unit which adjusts the gain of the control signal generating unit on the basis of the gain stored in the utterance absent period gain storing unit in an utterance present period.

An interior rearview mirror assembly suitable for use in a vehicle includes a variable reflectance reflective element, which includes an electrochromic medium, a first information display positioned to the rear of the variable reflectance reflective element, and a second information display. The mirror assembly further includes a single control for adjusting the luminous intensity of the first information display and the second information display and at least one light sensor, with the output of the control being generated responsive to a light level sensed by the at least one light sensor. In addition, the luminous intensity of the first information display and of the second information display increases responsive to the output of the control to compensate for any decrease in transmission of the electrochromic medium.

A headphone device includes: a sound reproduction unit having a diaphragm which is configured to perform sound reproduction based on a sound signal; a sound pickup unit configured to perform a sound pickup operation; a filtering unit configured to apply filtering to a picked-up sound signal obtained by the sound pickup unit, to give a noise-cancelling signal characteristic; a combining unit configured to combine the picked-up sound signal that has undergone filtering, and a listening sound signal which is inputted separately, to generate a sound signal supplied to the sound reproduction unit; and an abnormality determination unit configured to determine occurrence or non-occurrence of an abnormal sound, on the basis of a result of level detection of a sound signal obtained within a sound signal processing system that includes the filtering unit and the combining unit and is formed between the sound pickup unit and the sound reproduction unit.

A noise reduction device of the present invention comprises a control filter unit for generating a control sound signal to cancel out a noise, a control speaker for outputting a control sound according to the control sound signal from the control filter unit, an error microphone for detecting a residual sound by superimposing the noise upon the control sound output from the control speaker, and an obstacle detector for detecting an obstacle around the error microphone, wherein the control filter unit generates the control sound signal according to data from the error microphone and the obstacle detector.

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. 3

A low-delay signal processing system and method are provided which includes a delta-sigma analog-to-digital converter, an oversampling processor, and a delta-sigma digital-to-analog converter. The delta-sigma analog-to-digital converter receives an input or audio signal and generates a digital sample signal at a high oversampling rate. The oversampling processor is connected to the analog-to-digital converter for processing the digital sample signal at the high oversampling rate with low-delay. The delta-sigma digital-to-analog converter is connected to the oversampling processor for receiving the digital sample signal at the high oversampling rate with low-delay for generating an analog signal. The oversampling processor includes a low-delay filter and a programmable delay element. In this manner, the analog signal is produced with a low delay and high accuracy.

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 method and system for active noise cancellation is provided. The system employs subband processing, and preferably implements over-sampled filterbank. The system is applicable to adaptive noise cancellation, adaptive echo cancellation for portable listening devices, such as headsets and other similar listening devices.

A noise reducing device includes: an acoustic-to-electric conversion section for collecting noise and outputting an analog noise signal; an analog-to-digital conversion section for converting the analog noise signal into a digital noise signal; and a digital processing section for generating a digital noise reducing signal on a basis of the digital noise signal and a desired parameter. The device further includes: a retaining section for retaining a plurality of parameters corresponding to a plurality of kinds of noise characteristics; a setting section for setting one of the plurality of parameters as the desired parameter of the digital processing section; a digital-to-analog conversion section for converting the digital noise reducing signal into an analog noise reducing signal; and an electric-to-acoustic conversion section for outputting noise reducing sound on a basis of the analog noise reducing signal.

According to an aspect, a sound outputting device includes a front unit, a first side unit, a second side unit, a sound transmitting portion, and a piezoelectric speaker. The first side unit is coupled to one end portion of the front unit. The second side unit is coupled to another end portion of the front unit. The sound transmitting portion is provided in the first side unit for transmitting a sound via cartilage conduction. The piezoelectric speaker vibrates the sound transmitting portion.

A headset for voice communication is disclosed, the headset comprising at least one earphone having a speaker and one or more microphones. The headset is configured to be operated in a first mode in which an electronic noise cancelling circuit is configured to receive ambient audio via at least a first of the one or more microphones to implement an active noise cancelling function and to provide a noise cancelling audio signal to the speaker, and in a second mode in which ambient audio is provided as a hear-through audio signal to the speaker. The headset for voice communication is configured to detect whether a call is ongoing, and to provide a call signal in response to the detection. The headset comprises the electronic noise cancelling circuit, a voice activity detection unit configured to indicate when a user speaks, a switching element configured to switch the headset between operating in the first mode and operating in the second mode, wherein, when the headset is operated in the first mode and the call signal indicates that the user is not in a call, the switching element is configured to switch the headset from operating in the first mode to operating in the second mode when the voice activity detection unit indicates that the user speaks.

An active noise control system generates an anti-noise signal to drive a speaker to produce sound waves to destructively interfere with an undesired sound in a targeted space. The speaker is also driven to produce sound waves representative of a desired audio signal. Sound waves are detected in the target space and a representative signal is generated. The representative signal is combined with an audio compensation signal to remove a signal component representative of the sound waves based on the desired audio signal and generate an error signal. The active noise control adjusts the anti-noise signal based on the error signal. The active noise control system converts the sample rates of an input signal representative of the undesired sound, the desired audio signal, and the error signal. The active noise control system converts the sample rate of the anti-noise signal.

A noise control device according to the present invention is capable of reducing noises respectively arriving in a plurality of spaces which are acoustically independent from each other. The noise control device comprises: sound output means, which are respectively provided in the plurality of spaces so as to respectively correspond to the plurality of spaces, each for outputting a sound to a corresponding space; noise detection means, which is provided in at least one of the plurality of spaces, for detecting a noise arriving in the at least one of the plurality of spaces; and signal generation means which is a single means for generating, based on the noise detected by one of the noise detection means, a cancellation signal for canceling the noise, and outputting the generated cancellation signal to each of the plurality of sound output means.