Abstract: An echo canceler includes a signal-to-echo ratio calculating unit 103 and a residual echo suppressing unit 105. The signal-to-echo ratio calculating unit 103 computes 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 102, 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 ?(n), on the filter coefficient sequence of the update filter 102, which is obtained up to the previous operation. The residual echo suppressing unit 105 suppresses the echo component contained in the microphone input signal in accordance with the signal-to-echo ratio the signal-to-echo ratio calculating unit 103 computes.

Abstract: A control signal filter 2 receives 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 unit 4 updates coefficients of the control signal filter 2 in response to a sound source signal and an error signal. A disturbance detector 6 outputs a disturbance detection result in response to the error signal and an estimated secondary vibration/noise signal. An update controller 7 adjusts an update step of the filter coefficient update unit 4 in accordance with the disturbance detection result.

Abstract: 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.

Abstract: 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 D1; a delay controller that delays the low-band component by a delay amount D2; a delay controller that delays an output signal of the delay controller by a delay amount D3; a low-band echo canceller that generates a pseudo-echo signal delayed by a delay amount D1+D2; 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 2D1+D2. The delay controllers control the delay amounts D2 and D3 such that a tap length LA satisfies a condition of LA ?2D1+D2=D2+D3, the tap length LA indicating a response time of the adaptive filter in the full-band echo canceller.

Abstract: A control signal filter 2 receives 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 unit 4 updates coefficients of the control signal filter 2 in response to a sound source signal and an error signal. A signal-to-interference ratio measuring unit 5 outputs 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 controller 6 adjusts an update step of the filter coefficient update unit 4 in accordance with the signal-to-interference ratio.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An adaptive filter unit outputs a send-mid signal obtained by eliminating echo from a send-in signal, and a power comparing unit calculates a power ratio between received signal power and send-mid signal power. When a receiver ST detecting unit detects a single talk state at a receiving side, an acoustic coupling amount estimating unit estimates and updates the estimated amount of acoustic coupling from the power ratio. A residual echo power estimating unit estimates estimated residual echo power from the received signal power and the estimated amount of acoustic coupling, and a signal-to-echo ratio estimating unit estimates a ratio between the send-mid signal power and the estimated residual echo power. An amplitude suppression coefficient determining unit determines the amplitude suppression coefficient corresponding to the ratio, and an amplitude suppression unit amplitude suppresses the send-mid signal.

Abstract: 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.

Abstract: 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 according to the present invention 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.

Abstract: A target sound enhancement device 10 has a first beamformer 16 and a second beamformer 17 which are of different types. A vehicle interior environment model in which this target sound enhancement device 10 is mounted is stored in a vehicle interior environment model storage unit 13. A beamformer type determining unit 14 selects a most suitable beamformer according to the vehicle interior environment model for each of predetermined frequency bands, and a BF selector 15 outputs a signal in each frequency band to the beamformer selected. A signal combining unit 18 combines signals in the frequency bands in each of which the driver's voice outputted from the first beamformer 16 or the second beamformer 17 is enhanced.

Abstract: 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.

Abstract: An echo canceler includes a signal-to-echo ratio calculating unit 103 and a residual echo suppressing unit 105. The signal-to-echo ratio calculating unit 103 computes 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 102, 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 ?(n), on the filter coefficient sequence of the update filter 102, which is obtained up to the previous operation. The residual echo suppressing unit 105 suppresses the echo component contained in the microphone input signal in accordance with the signal-to-echo ratio the signal-to-echo ratio calculating unit 103 computes.

Abstract: A state deciding unit 2 makes a decision of double talk when both received signal and transmission signal are in a speech burst, and when the amount of reduction in an echo removal level per prescribed time period exceeds a predetermined threshold, the echo removal level being represented as a level difference between the transmission signal and a residual signal passing through the echo elimination by an adaptive filter 1, and when the amount of changes of the signal level of the received signal is less than a prescribed reference value.

Abstract: An adaptive filter unit 103 outputs a send-mid signal obtained by eliminating echo from a send-in signal, and a power comparing unit 107 calculates a power ratio between received signal power and send-mid signal power. When a receiver ST detecting unit 104 detects a single talk state at a receiving side, an acoustic coupling amount estimating unit 108 estimates and updates the estimated amount of acoustic coupling from the power ratio. A residual echo power estimating unit 109 estimates estimated residual echo power from the received signal power and the estimated amount of acoustic coupling, and a signal-to-echo ratio estimating unit 110 estimates a ratio between the send-mid signal power and the estimated residual echo power. An amplitude suppression coefficient determining unit 111 determines the amplitude suppression coefficient corresponding to the ratio, and an amplitude suppression unit 112 amplitude suppresses the send-mid signal.

Abstract: A state deciding unit 2 makes a decision of double talk when both received signal and transmission signal are in a speech burst, and when the amount of reduction in an echo removal level per prescribed time period exceeds a predetermined threshold, the echo removal level being represented as a level difference between the transmission signal and a residual signal passing through the echo elimination by an adaptive filter 1, and when the amount of changes of the signal level of the received signal is less than a prescribed reference value.

Abstract: A tone control apparatus is provided with a desired filter response input unit 11 for inputting a desired filter response into the tone control apparatus, a spectrum calculating unit 12 for calculating a Fourier spectrum for the set filter response which is inputted by the desired filter response input unit 11, a spectrum smoothing processing unit 13 for performing smoothing processing on the Fourier spectrum calculated by the spectrum calculating unit 12, a cepstrum calculating unit 14 for converting the Fourier spectrum smoothed by spectrum smoothing processing unit 13 into a cepstrum, and an LMA filter 15 to which the cepstrum calculated by the cepstrum calculating unit 14 is set as the filter factor of the LMA filter. The tone control apparatus also has an input terminal 16 for inputting a sound signal into the LMA filter 15, and an output terminal 17 for outputting a sound signal.