Mitsubishi Electric Corporation

Atsuyoshi Yano

Tomoharu Awano

Takashi Sudo

Satoru Furuta

Bunkei Matsuoka

Takashi Mikami

Masaru Kimura

Nobuaki Tanaka

Ikuo Kajiyama

Atsushi Hotta

Jin Hirano

A microphone array includes first and second microphones (Ma, Mb) placed on a first axis (f), a third microphone (Mc) placed on a plane (fg) formed by the first axis and a second axis (g) and at a position other than on the first axis, and a fourth microphone (Md) placed on a third axis (h), and at a position other than on the plane formed by the first and the second axes, and a processing circuit generates signals (Cx, Cy, Cz) having bidirectionality in first, second and third mutually perpendicular directions (x, y, z), and an omnidirectional signal (Cw), based on signals (Ba to Bd) obtained by sound collection by means of the first to fourth microphones. It is possible to generate signals having bidirectionality in mutually perpendicular directions, and an omnidirectional signal, without using special microphones, and without excessive restrictions with regard to the placement of the microphones.

Sound collection and playback apparatus, and recording medium

A sound signal control device in a device including an input transducer to detect sound in a space in a vehicle, a sensor to image an occupant in the space, and an output transducer to emit sound into the space includes: a controller to generate information indicating a position of a head of the occupant and information indicating a state of the occupant, based on an image imaged by the sensor; a processor to generate a cancellation signal for cancelling noise at the position based on a sound signal representing sound detected by the input transducer and the information, and generate a control signal for controlling sound at the position based on the cancellation signal; and a converter to cause the output transducer to emit a sound corresponding to the control signal. The processor adjusts a degree to which the noise is cancelled, based on the information indicating the state.

Sound signal control device and method, and recording medium

An engine sound control device includes: a setter to set point information including coordinates indicating one of multiple cells of a driving state space represented by a coordinate system with parameters indicating a driving state as axes, and spectral information of a target engine sound at the cell; a setter to set region information indicating a driving scene region; a processor to perform an interpolation process to calculate spectral information of an engine sound for each of target cells of the multiple cells for which the point information is not set, based on the point information and region information, and generate a map including spectral information of an engine sound at each cell, from the point information and information obtained by the process; a processor to output a control parameter based on the map; and a controller to cause a unit to output a sound based on the control parameter.

Engine sound control device, engine sound control method, and non-transitory computer-readable medium

There are provided a control signal generation unitthat generates a control signal on the basis of a cosine wave signal and a sine wave signal whose frequencies are a control frequency identified according to a vibration noise source, and a correction value update unit that updates a correction value to a value for decreasing signal power of an error signal on the basis of a relationship between increase and decrease of the signal power of the error signal obtained from remaining vibration noise that remains after interference sound that is generated on the basis of the control signal and propagates through a secondary route interferes with vibration noise generated from the vibration noise source and increase and decrease of the correction value used for correction of the control frequency.

Active vibration noise control apparatus

An active noise control apparatus () includes: a sound source signal generating unit () generating a sound source signal from a control frequency determined in accordance with a noise source (); a control signal filter () generating an original control signal by filtering the sound source signal; a stabilization processing unit () generating a control signal by filtering the original control signal to allow a signal in a frequency band including the control frequency to pass through, and to block a signal in a frequency band including disturbance added to the noise; a reference signal filter () generating a reference signal by filtering the sound source signal. The apparatus further includes: a filter coefficient updating unit () updating a filter coefficient sequence of the control signal filter using an error signal being an interference between a secondary noise generated from the control signal and the noise, and the reference signal.

Active noise control apparatus

An acceleration detectorincludes a direction vector setting unitfor setting a direction vector u in accordance with detection arguments a and b that define a target detection direction in a three-axis rectangular coordinate system of xyz orthogonal to each other; and an inner product computing unitfor obtaining a detected acceleration signal v(n) by calculating an inner product of the direction vector u and acceleration signals x(n), y(n) and z(n) on the individual axes observed in the rectangular coordinate system.

Acceleration detector and active noise-control device

A variable update step size is determined in proportion to a magnitude ratio or magnitude difference between a first residual signal and a second residual signal. The first residual signal is obtained by using adaptive filter coefficient sequence, where the adaptive filter coefficient sequence has been obtained in previous operations of the adaptive equalizer. The second residual signal is obtained by using a prior update adaptive filter coefficient sequence, where the prior update adaptive filter coefficient sequence is obtained by performing a coefficient update with an arbitrary prior update step size on the adaptive filter coefficient sequence having been obtained in previous operations of the adaptive equalizer.

Adaptive equalizer, acoustic echo canceller device, and active noise control device

A first control signal filter to which a cosine wave oscillating at a control frequency is input; a second control signal filter to which a sine wave oscillating at the control frequency is input; a control signal adder for outputting a control signal generated by adding an output of the first control signal filter and an output of the second control signal filter; a filter coefficient update unit for updating filter coefficients of the first control signal filter and the second control signal filter; and a frequency correction value calculation unit for calculating a frequency correction value for correcting the control frequency on the basis of the control signal and the control frequency.

A control signal filterreceives a sound source signal determined by a control frequency specified in conformity with the vibration/noise source that produces vibration/noise, and outputs a control signal. A filter coefficient update unitupdates coefficients of the control signal filterin response to a sound source signal and an error signal. A signal-to-interference ratio measuring unitoutputs a signal-to-interference ratio determined from the vibration/noise and the interference contained in the error signal in response to the control frequency and error signal. An update controlleradjusts an update step of the filter coefficient update unitin accordance with the signal-to-interference ratio.

Active vibration/noise control apparatus

An echo cancellation device includes: a full-band echo canceller that generates a pseudo-echo signal; a downsample processor that downsamples a received signal and extracts a low-band component delayed by a delay amount D; a delay controller that delays the low-band component by a delay amount D; a delay controller that delays an output signal of the delay controller by a delay amount D; a low-band echo canceller that generates a pseudo-echo signal delayed by a delay amount D+D; and an upsample processor that upsamples the low-band pseudo-echo signal to generate a full-band pseudo-echo signal delayed by the delay amount 2D+D. The delay controllers control the delay amounts Dand Dsuch that a tap length Lsatisfies a condition of L&#x2267;2D+D=D+D, the tap length Lindicating a response time of the adaptive filter in the full-band echo canceller.

Echo cancellation device

A control signal filterreceives a sound source signal determined by a control frequency specified in accordance with the vibration/noise source that produces vibration/noise, and outputs a control signal. A filter coefficient update unitupdates coefficients of the control signal filterin response to a sound source signal and an error signal. A disturbance detectoroutputs a disturbance detection result in response to the error signal and an estimated secondary vibration/noise signal. An update controlleradjusts an update step of the filter coefficient update unitin accordance with the disturbance detection result.

A reverberation suppression device comprises: an echo canceller that removes an echo component included in an input signal; a howling suppressor that detects occurrence of howling based on a frequency characteristic of the input signal from which the echo component has been removed and attenuates a frequency level of a component of the detected howling; and an initial sound suppressor that detects a sound section of the input signal in which the frequency level of the howling component has been attenuated and suppresses a signal value at a sound start portion of the detected sound section.

Reverberation suppression device

An echo canceler includes a signal-to-echo ratio calculating unitand a residual echo suppressing unit. The signal-to-echo ratio calculating unitcomputes a signal-to-echo ratio SE(n) indicating a ratio of an echo component to a received signal x(n) from a first residual signal and a second residual signal. The first residual signal is obtained using a filter coefficient sequence of an update filter, which is obtained up to the previous operation. The second residual signal is obtained using an updated filter coefficient sequence that undergoes a coefficient update which is performed, using an arbitrary update step size &#x3bc;(n), on the filter coefficient sequence of the update filter, which is obtained up to the previous operation. The residual echo suppressing unitsuppresses the echo component contained in the microphone input signal in accordance with the signal-to-echo ratio the signal-to-echo ratio calculating unitcomputes.

Echo canceler and echo detector

An active vibration noise control apparatus with which vibration noise can be reduced stably and effectively by preventing divergence of a filter coefficient or a delay in convergence due to an effect of a transfer characteristic on a secondary path. The active vibration noise control apparatus calculates an update step size in accordance with a magnitude of a gain in the transfer characteristic corresponding to a frequency of vibration noise, where the transfer characteristic is on the secondary path for propagation of a secondary vibration noise for reducing the vibration noise, and updates the filter coefficient on the basis of the calculated update step size.

An echo cancelling device splits a low-band signal through LPFs having characteristics which do not cause aliasing during downsampling of downsamplers, and splits a high-band signal through HPFs having characteristics which do not cause aliasing during downsampling of downsamplers. The echo canceling device generates a mid-band signal by subtracting the low-band signal and the high-band signal from a pre-split signal by adder-subtractors, and cancels an echo on a band-by-band basis.

Growing community of inventors

Tokyo, Japan

Atsuyoshi Yano