EP1261961B1 - Verfahren und systeme für rauschunterdrückung für räumlich versetzte signalquellen - Google Patents

Verfahren und systeme für rauschunterdrückung für räumlich versetzte signalquellen Download PDF

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Publication number
EP1261961B1
EP1261961B1 EP01904915A EP01904915A EP1261961B1 EP 1261961 B1 EP1261961 B1 EP 1261961B1 EP 01904915 A EP01904915 A EP 01904915A EP 01904915 A EP01904915 A EP 01904915A EP 1261961 B1 EP1261961 B1 EP 1261961B1
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EP
European Patent Office
Prior art keywords
source
filter
filters
signal
channel
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EP01904915A
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English (en)
French (fr)
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EP1261961A1 (de
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Leonid Krasny
Ali S. Khayrallah
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Ericsson Inc
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Ericsson Inc
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Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17857—Geometric disposition, e.g. placement of microphones
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17821—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the input signals only
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1783—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
    • G10K11/17837—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions by retaining part of the ambient acoustic environment, e.g. speech or alarm signals that the user needs to hear
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17853—Methods, e.g. algorithms; Devices of the filter
    • G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1787—General system configurations
    • G10K11/17873—General system configurations using a reference signal without an error signal, e.g. pure feedforward

Definitions

  • Speech enhancement using a soft-decision noise-suppression filter IEEE Trans. on Acoustics, Speech, and Signal Processing, ASSP-28:137-145, 1980.
  • the speech and the noise tend to have similar spectral distributions. Under these conditions, the single-microphone echo suppression technique may not yield substantial improvement in speech intelligibility.
  • the signal and the echo in a car environment are acoustical fields which typically have different spatial characteristics. The spatial separation of the speech and the echo can be exploited to reduce the noise level.
  • antenna array processing may achieve effective rejection of underwater noise (ambient noise and ocean reverberation) as described, for example, in L.G. Krasny, Spatial processing of acoustic signals in a plane-parallel waveguide, Sov.Phys.Accoust., 30, 4, 495-501, 1984 and A.B. Baggeroer, W.A. Kuperman and H. Shmidt, "Matched-field processing: source localization in correlated noise as an optimum parameter estimation problem," J.Acoust.Soc.Am. 83, 571-587,1988.
  • equation (1) is based on an assumption that the antenna array is located in a free-field propagation channel.
  • the free-field propagation model does not take into account affects, such as waveguide sound propagation, typically found in a car cabin environment. Accordingly, there is a need for a system to reduce the noise associated with spatially displaced signal sources.
  • the present invention may meet this need by providing methods, systems and mobile terminals which use the spatial characteristics associated with the respective locations of various signal sources within the receiver environment, such as a vehicle, in processing received signals from the signal sources.
  • the use of the spatial characteristics may provide improved noise reduction and further, in various embodiments of the present invention, may be used to apply a selected suppression level to one or more of the signal sources.
  • a selected suppression level For example, in a vehicle hands-free speech reception system, far-end feedback from a speaker in the vehicle may be substantially suppressed while speech from a driver and a passenger in the vehicle may be processed with substantially zero decibels of suppression.
  • the suppression levels may be user selectable.
  • a noise reduction system including a plurality off receive channels coupled to a plurality of signal inputs.
  • Each of the receive channels including a plurality of filters that output channel component filtered signals.
  • Each of the filters may be responsive to at least one of the plurality of signal inputs and have coefficients based on a source spatial characteristic associated with the respective receive channel.
  • the receive channels further include a channel combiner circuit that combines the channel component filtered signals to provide a channel filtered signal.
  • the noise suppression system further includes a constraint circuit that outputs a suppression for at least one of the channel filtered signals and an output combiner circuit responsive to the plurality of receive channels that combines the channel filtered signals.
  • the channel combiner circuit may include a summer that receives the channel component filtered signals and a weighting filter that filters an output of the summer to provide the channel filtered signal.
  • the weighting filter may be responsive to the constraint circuit.
  • the constraint circuit may be responsive to a user input designating a desired suppression for at least one of the plurality of receive channels. In one embodiment, the constraint circuit outputs coefficients of the weighting filter associated with the at least one of the plurality of receive channels as the suppression for the at least one of the channel filtered signals which is associated with the at least one of the plurality of channels based on the designated desired suppression and the source spatial characteristic associated with the at least one of the plurality of channels.
  • the noise suppression system includes a coefficient estimation circuit that adjusts the coefficients of the plurality of filters of each of the plurality of receive channels responsive to the audio inputs.
  • the coefficient estimation circuit may be configured to adjust the coefficients of the plurality of filters of each of the plurality of receive channels based on the source spatial characteristic associated with the respective receive channels.
  • a plurality of receivers generate the plurality of signal inputs.
  • the coefficient estimation circuit adjusts the coefficients of the plurality of filters of each of the plurality of receive channels based on the source spatial characteristic associated with the respective receive channels using a Green function for each of the plurality of receive channels that corresponds to a propagation channel from a signal source associated with the respective channel to the plurality of receivers.
  • the receivers may be spatially displaced microphones and the signal sources associated with the respective channels may be sound sources in a vehicle.
  • a noise reduction system for a multi-source environment including a plurality of filters coupled to a plurality of signal inputs.
  • the plurality of filters output component filtered signals.
  • Each of the filters may be responsive to at least one of the plurality of signal inputs and have coefficients based on source spatial characteristics associated with sources in the multi-source environment.
  • the system further includes an output combiner circuit responsive to the plurality of filters that combines the component filtered signals and a coefficient estimation circuit that adjusts the coefficients of the plurality of filters based on the source spatial characteristics.
  • the coefficient estimation circuit may include a constraint circuit that outputs a suppression associated with at least one of the sources in the multi-source environment.
  • a vehicle hands-free speech reception system including a plurality of spatially displaced microphones in the vehicle and a plurality of receive channels coupled to the microphones.
  • Each of the receive channels is associated with a respective one of a plurality of spatial positions in the vehicle.
  • Each of the receive channels includes a plurality of filters that output channel component filtered signals, each of the filters responsive to at least one of the microphones and having coefficients based on a source spatial characteristic associated with the spatial position in the vehicle associated with the respective receive channel, and a channel combiner circuit that combines the channel component filtered signals to provide a channel filtered signal.
  • a constraint circuit outputs a suppression for at least one of the channel filtered signals and an output combiner circuit responsive to the plurality of receive channels combines the channel filtered signals.
  • One of the plurality of spatial positions may be a passenger position and at least one of the plurality positions may be a noise source.
  • the noise source may be a speaker and the speaker and the vehicle hands-free reception system may be a telephone system.
  • a method for noise reduction including receiving signals and processing the plurality of received signals through a first filter having coefficients associated with a first source spatial characteristic to provide a first filtered signal and through a second filter having coefficients associated with a second source spatial characteristic to provide a second filtered signal.
  • the first filtered signal is processed through a third filter having coefficients associated with a selected suppression for the first source to provide a first suppressed signal and the second filtered signal is processed through a fourth filter having coefficients associated with a selected suppression for the second source to provide a second suppressed signal.
  • the first and second suppressed signals are combined.
  • the signals are preferably received from N spatially displaced microphones and processed through an associated one of N filters comprising the first filter and outputs of the N filters comprising the first filter are combined to provide the first filtered signal.
  • the received signals from each of the N microphones are also processed through an associated one of N filters comprising the second filter and outputs of the N filters comprising the second filter are combined to provide the second filtered signal.
  • the coefficients of the N filters comprising the first filter and the N filters comprising the second filter are estimated.
  • the coefficients of the third filter may be estimated responsive to a constraint value associated with the first source and the coefficients of the fourth filter may be estimated responsive to a constraint value associated with the second source.
  • the first source may be a wanted source and the step of processing the first filtered signal through a third filter may include processing the first filtered signal through the third filter wherein the third filter provides a selected suppression of about 0 decibels.
  • the second source may be an unwanted source and the step of processing the second filtered signal through a fourth filter may include processing the second filtered signal through the fourth filter wherein the fourth filter provides a selected suppression of at least about -3 decibels.
  • a method for noise reduction including receiving signals from N spatially displaced microphones and processing the received signals from each of the N microphones through an associated one of N filters, each of the N filters having coefficients associated with a plurality of source spatial characteristics and a selected suppression for a source associated with each of the plurality of source spatial characteristics.
  • the processed received signals are combined.
  • the coefficients of the N filters are estimated responsive to constraint values associated with the sources associated with each of the plurality of source spatial characteristics.
  • Operations of the present invention may be described by modeling the signal field in a car as a superposition of the signals from M users and background noise (road noise, wind noise, engine noise).
  • background noise road noise, wind noise, engine noise.
  • U out ( w ) is the Fourier transform of the antenna processor output
  • Equation (4) describes a multichannel system which includes M spatial channels ⁇ U 1 ( w ),.., U M ( w ) ⁇ .
  • the frequency responses of the filters H ( w ; r i , R m ) for each of these channels are matched with the spatial characteristics of the signal from the m -th user and the background noise and satisfy the following equation: where g -1 N ( w ; r i , r k ) denotes elements of the matrix g -1 N which is the inverse of the noise spatial correlation function g N ( w ; r i , r k ).
  • the noise reduction system described by equation (4) utilizes determinate information about the spatial characteristic of the source signal field in a vehicle.
  • the array processing in the m -th spatial channel may be optimized to detect a signal from the m -th source against the background noise.
  • the noise spatial correlation function g N ( w ; r i , r k ) is a priori unknown, it may still be determinate as the inverse correlation matrix g -1 N ( w ; r i , r k ) can be estimated by using the adaptive algorithm, for instance: where g -1 N ( n ) ( w ; r i , r k ) is an estimate of the inverse noise correlation matrix g -1 N ( w ; r i , r k ) at the n -th iteration, m g is a convergence factor, and the functions D ( n ) ( w , r i ) satisfy the following equation: As seen in the equations, the functions D ( n ) ( w , r i ) at the n -th frame are calculated using the inverse noise correlation matrix at the previous ( n -1)-th frame where a frame may be selected as a determined time interval and
  • the output voltages of the M spatial channels may be accumulated with the weighting functions (filters) ⁇ W 1 ( w ),.., W M ( w ) ⁇ , which satisfy the following equation: where ⁇ -1 mn ( w ) denotes elements of the matrix ⁇ -1 ( w ) which is the inverse of the matrix ⁇ ( w ) with elements: and ⁇ B 1 ( w ),.., B M ( w ) ⁇ may be user selectable functions. The choice of these functions depends on the desired signal processing result.
  • B i ( w ) 0 theoretically provides substantially complete suppression (cancellation). Intermediate values may be provided for other levels of suppression.
  • FIG. 2 is a schematic block diagram illustrating an embodiment of the present invention.
  • the noise reduction system includes M spatial channels 205a, 205b.
  • the microphones are preferably spatially displaced.
  • the N filters 210 output channel component filtered signals.
  • Each of the N filters 210 is responsive to at least one of the signal inputs from the microphones 220 and has coefficients based on a source spatial characteristic associated with the respective channel, for example, with a particular spatial location signal source within a vehicle, such as the driver, with which the respective channel is associated.
  • a summer 230 is included in each of the M channels 205a, 205b.
  • the outputs of the summers ⁇ 1,.., ⁇ M 230 are filtered through the suppression (weighting) filters W 1,.., W M 240 which, in combination with the summers 230 provides a channel combiner circuit that outputs a suppression for the channel filtered signals from the filters 210 in the illustrated embodiment.
  • the weighting filters 240 are responsive to a constraint circuit 270 to provide a desired suppression to each of the spatial location signal sources.
  • the filtered results are summed in a summer (channel output combiner circuit) 250 and the resulting sum is a signal U out in which the background noise may be suppressed and signals from unwanted sources may be canceled (substantially fully suppressed).
  • the coefficients are calculated according to equation (6) and are updated responsive to the signal inputs from the microphones 220 .
  • a constraint circuit 270 calculates the frequency responses of the filters W 1,.., W M 240 (by providing the filter coefficients), preferably according to equation (8).
  • the constraint circuit 270 may also generate outputs based on constraint functions B 1 ( w ),.., B M ( w ). As mentioned above, choice of these functions depends on the goal of the circuit, such as, to keep clear speech from all users or to suppress signals from some unwanted signal sources.
  • the constraint functions may be user selectable inputs designating a desired suppression for each of the receive channels (and thereby the associated spatial location signal source such as a driver, a passenger or a speaker). As shown in FIG. 2 and as can be seen from equation (8), the constraint circuit 270 receives the frequency responses of the filters 210 as inputs.
  • N filters 310 filters H 01,.., H 0 N ) are provided which filter N digitally sampled signals received from N microphones 320.
  • the filters 310 are responsive to the signals from the microphones 320 and have coefficients defining their frequency response based on source spatial characteristics associated with sources in the multi-user environment of the system as, for example, is shown in the embodiment described by equation (12) below.
  • the component filtered signals from the filters 310 are combined in an output combiner circuit 350 (a summer in the illustrated embodiment) and the resulting sum is a signal U out in which the background noise may be selectively suppressed.
  • the constraint circuit 370 calculates the frequency responses of the filters W 1 ,.., W M according to equation (8) using constraint functions B 1 ( w ),..., B M ( w ) to select signal suppression levels for wanted and unwanted signal sources.
  • the coefficient estimation circuit 360 and the constraint circuit 370 may be combined in constrained coefficient estimation circuit 375 .
  • the system may include two spatial channels U 1 (w) and U 2 ( w ).
  • the frequency responses of the filters H ( w ; r i , R 1 ) at the first channel may be matched with the spatial coordinates R 1 of the driver, and the frequency responses of the filters H ( w ; r i , R 2 ) at the second channel may be matched with the spatial coordinates R 2 of a loudspeaker which creates echo signal.
  • the frequency responses of the filters H ( w ; r i , R 1 ) at the first channel may be matched with the spatial coordinates R 1 of the driver
  • the frequency responses of the filters H ( w ; r i , R 2 ) at the second channel may be matched with spatial coordinates R 2 of a loudspeaker generating the far-end signal
  • the frequency responses of the filters H ( w ; r i , R 3 ) at the third channel may be matched with the spatial coordinates R 3 of the passenger.
  • the functions B 1 ( w ) ... B M ( w ) can be chosen to produce a desired overall effect. For example, there is a compromise that may be achieved among several goals. This may be illustrated by a further example.
  • source 1 is a desired speech signal
  • source 2 is a fan on the dashboard of a car that needs to be suppressed and the ambient noise is a mix of road noise and engine noise.
  • the spectra S 1 ( w ) and S 2 ( w ) are illustrated in FIGs. 4A through 4C for purposes of illustrating this example as well as the spectrum of the noise S noise ( w ).
  • B 1 ( w ) the goal may be to conserve source 1 while suppressing the noise.
  • B 2 ( w ) it is preferable to attenuate source 2.
  • Illustrative resulting choices for this example are shown in FIGs. 5A and 5B . It is to be understood that the spectra and constraints are illustrated in a simplified manner for purposes of this example to illustrate the flexibility provided through choosing the constraint functions to reflect the spectra of desired and undesired signals.
  • FIG. 6 A computer simulation of a system according to an embodiment of the present invention is shown in FIG. 6 , which illustrates the output signal-to-noise ratio as a function of frequency.
  • Solid lines correspond to an embodiment of the present invention described by equation (4), and dashed lines correspond a conventional system based on equation (1).
  • the simulations are based on 4-element antenna array and two user sources.
  • the present invention allows substantial (25-30 dB) attenuation of the noise field and unwanted signal without substantial suppression and/or degradation of the target (desired) signal.
  • each block of the flowchart illustrations and the block diagram illustrations of FIGs. 2 and 3, and combinations of blocks in the flowchart illustrations and the block diagram illustrations can be implemented by computer program instructions.
  • These program instructions may be provided to a processor to produce a machine, such that the instructions which execute on the processor create means for implementing the functions specified in the flowchart and block diagram block or blocks.
  • the computer program instructions may be executed by a processor to cause a series of operational steps to be performed by the processor to produce a computer implemented process such that the instructions which execute on the processor provide steps for implementing the functions specified in the flowchart and block diagram block or blocks.
  • blocks of the flowchart illustrations and the block diagrams support combinations of means for performing the specified functions, combinations of steps for performing the specified functions and program instruction means for performing the specified functions. It will also be understood that each block of the flowchart illustrations and block diagrams, and combinations of blocks in the flowchart illustrations and block diagrams, can be implemented by special purpose hardware-based systems which perform the specified functions or steps, or combinations of special purpose hardware and computer instructions.
  • filters 210 , 310 , coefficient estimation circuits 260 , 360 and constraint circuits 270 , 370 may all be implemented as code executing on a processor, as custom chips or as a combination of the above.
  • Operations begin at block 500 with determination of a desired suppression for each of a plurality of spatial location signal sources.
  • a spatial location associated with a driver and a passenger respectively may be provided a desired suppression of substantially zero decibels.
  • a spatial location associated with a speaker outputting the far-end speech signal into the vehicle compartment may be associated with a desired suppression of about minus three decibels or, preferably, with substantially complete suppression providing effective cancellation of far-end echo signals.
  • one of the channels may be associated with each of the spatial location signal sources (block 505 ).
  • Signals are received from the spatial location signal sources (block 510 ).
  • the signals are received at N spatially displaced microphones providing an antenna array.
  • N filters H(w) are preferably provided in each channel with one of the filters being associated with each of the N microphone sources.
  • Coefficients are estimated for each of the filters H(w) and for the suppression (weighting) filters W(w) associated with each channel (block 515). It is further to be understood that, for embodiments such as that illustrated in FIG. 3, the estimation of the coefficients H(w) and W(w) are combined and result in generation of the coefficients of the filters 310 as shown in FIG. 3 .
  • the received signals are then processed through the receive channels to provide a plurality of process filtered signals, each of which is associated with one of the displaced spatial location signal sources as will now be described with reference to blocks 520 through 525 .
  • the received signals are processed through associated ones of the N filters corresponding to the respective N microphones in each of the plurality of channels (block 520 ).
  • the outputs of the filters within each channel are combined (block 525 ).
  • a selected suppression is applied to the received signals by processing the combined outputs from the N filters H(w) of each channel through a suppression filter W(w) for each channel (block 530 ).
  • the suppression filters W(w) have coefficients associated with a selected suppression as determined at block 500.
  • the selected suppressions may be user selectable or may be otherwise set.
  • the filter processing and suppression responsive to a spatial location associated with each signal source may be combined into a single composite filtering step, for example as with the illustrated embodiment of FIG. 3 . Accordingly, operations at block 520 through 530 described above may be carried out by processing the signal from each of the end microphones through an associated filter having coefficients based upon signal source spatial characteristics and a desired suppression for each of the displaced spatial location signal sources. In either case, the outputs of the respective filters acting as suppression filters may then be combined to generate a signal (block 535 ).

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Health & Medical Sciences (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Noise Elimination (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)

Claims (22)

  1. Rauschreduzierungssystem, umfassend:
    eine Vielzahl von Empfangskanälen (205a, 205b, ...), gekoppelt mit einer Vielzahl von Signaleingaben (220), wobei jeder aus der Vielzahl von Empfangskanälen umfasst,
    eine Vielzahl von Filtern (210), die kanalkomponenten-gefilterten Signale ausgeben, wobei jeder aus der Vielzahl von Filtern auf mindestens eine von der Vielzahl von Signaleingaben reagiert und mit Koeffizienten basierend auf einer Quellenraumcharakteristik, die mit dem jeweiligen Empfangskanal in Verbindung steht, und
    eine Kanalkombiniererschaltung (230), die die kanalkomponenten-gefilterten Signale kombiniert, um ein kanalgefiltertes Signal vorzusehen; und
    eine Ausgabekombiniererschaltung (250), die auf die Vielzahl von Empfangskanälen reagiert, die die kanal-gefilterten Signale kombiniert.
  2. System nach Anspruch 1, wobei das System ferner eine Beschränkungsschaltung umfasst, die eine Unterdrückung für mindestens eines der kanal-gefilterten Signale ausgibt.
  3. System nach Anspruch 2, wobei die Kanalkombiniererschaltung ferner umfasst:
    einen Addierer, der die kanalkomponenten-gefilterten Signale empfängt; und
    einen Wichtungsfilter, der eine Ausgabe des Addierers kombiniert, um das kanal-gefilterte Signal vorzusehen.
  4. System nach Anspruch 3, wobei der Wichtungsfilter auf die Beschränkungsschaltung reagiert.
  5. System nach Anspruch 4, wobei die Beschränkungsschaltung auf eine Benutzereingabe reagiert, die eine gewünschte Unterdrückung für mindestens einen aus der Vielzahl von Empfangskanälen bestimmt.
  6. System nach Anspruch 5, wobei die Beschränkungsschaltung Koeffizienten des Wichtungsfilters, der mit dem mindestens einen aus der Vielzahl von Empfangskanälen in Verbindung steht, als die Unterdrückung für das mindestens eine von den kanal-gefilterten Signalen ausgibt, was mit dem mindestens einen aus der Vielzahl von Kanälen in Verbindung steht, basierend auf der bestimmten gewünschten Unterdrückung und der Quellenraumcharakteristik, verbunden mit dem mindestens einen aus der Vielzahl von Kanälen.
  7. System nach einem beliebigen der Ansprüche 2-6, wobei die Beschränkungsschaltung eine Unterdrückung für mindestens eines der kanal-gefilterten Signale basierend auf einen Frequenzspektrum der Signalquelle ausgibt, die mit dem Empfangskanal in Verbindung steht, der das mindestens eine der kanal-gefilterten Signale vorsieht.
  8. System nach einem beliebigen der Ansprüche 1-7, wobei das System ferner eine Koeffizientenbewertungsschaltung umfasst, die die Koeffizienten der Vielzahl von Filtern von jedem aus der Vielzahl von Empfangskanälen justiert, die auf die Signaleingaben reagieren.
  9. System nach Anspruch 8, wobei die Koeffizientenbewertungsschaltung ferner konfiguriert ist, die Koeffizienten der Vielzahl von Filtern von jedem aus der Vielzahl von Empfangskanälen basierend auf der Quellenraumcharakteristik zu justieren, die mit den jeweiligen Empfangskanälen in Verbindung steht.
  10. System nach Anspruch 9, ferner umfassend eine Vielzahl von Empfängern, die die Vielzahl von Signaleingaben generieren, und wobei die Koeffizientenbewertungsschaltung die Koeffizienten der Vielzahl von Filtern von jedem aus der Vielzahl von Empfangskanälen justiert basierend auf der Quellenraumcharakteristik, die mit den jeweiligen Kanälen in Verbindung steht, unter Verwendung einer Green-Funktion für jeden aus der Vielzahl von Empfangskanälen, die einem Ausbreitungskanal von einer Signalquelle, die mit dem jeweiligen Kanal in Verbindung steht, zu der Vielzahl von Empfängern entspricht.
  11. System nach Anspruch 10, wobei die Empfänger räumlich versetzte Mikrofone sind und die mindestens eine Signalquelle, die mit den jeweiligen Kanälen in Verbindung steht, mindestens eine Schallquelle ist.
  12. System nach Anspruch 11, wobei die räumlich versetzten Mikrofone und die mindestens eine Schallquelle in einem Fahrzeug sind.
  13. Empfangskanal nach einem beliebigen der Ansprüche 1-12.
  14. System nach Anspruch 1, worin das System ein Freihand-Sprachempfangssystem in einem Fahrzeug ist, wobei das System ferner umfasst:
    eine Vielzahl von räumlich versetzten Mikrofonen in dem Fahrzeug, jedes der Mikrofone mit der Vielzahl von Empfangskanälen gekoppelt, um die Vielzahl von Signaleingaben vorzusehen; und
    wobei jeder der Empfangskanäle mit einer jeweiligen aus einer Vielzahl von räumlichen Positionen in dem Fahrzeug in Verbindung steht, und wobei jede der Quellenraumcharakteristika, die mit den jeweiligen Empfangskanälen in Verbindung stehen, mit einer jeweiligen aus einer Vielzahl von räumlichen Positionen in dem Fahrzeug in Verbindung steht.
  15. System nach Anspruch 14, wobei mindestens eine aus der Vielzahl von räumlichen Positionen eine Passagierposition ist und mindestens eine aus der Vielzahl von Positionen eine Rauschquelle ist.
  16. System nach Anspruch 15, wobei die Rauschquelle ein Lautsprecher ist und wobei der Lautsprecher und das Freihand-Empfangssystem ein Telefonsystem umfassen.
  17. Verfahren für eine Rauschreduzierung, umfassend:
    Empfangen einer Vielzahl von empfangenen Signalen (220);
    Bearbeiten der Vielzahl von empfangenen Signalen durch einen ersten Filter (210, 230 in 205a) mit Koeffizienten, die mit einer ersten Quellenraumcharakteristik in Verbindung stehen, um ein erstes gefiltertes Signal vorzusehen;
    Bearbeiten der Vielzahl von empfangenen Signalen durch einen zweiten Filter (210, 230 in 205b) mit Koeffizienten, die mit einer zweiten Quellenraumcharakteristik in Verbindung stehen, um ein zweites gefiltertes Signal vorzusehen;
    Bearbeiten des ersten gefilterten Signals durch einen dritten Filter (240 in 205a) mit Koeffizienten, die mit einer ausgewählten Unterdrückung für die erste Quelle in Verbindung stehen, um ein erstes unterdrücktes Signal vorzusehen;
    Bearbeiten des zweiten gefilterten Signals durch einen vierten Filter (240 in 205b) mit Koeffizienten, die mit einer ausgewählten Unterdrückung für die zweite Quelle in Verbindung stehen, um ein zweites unterdrücktes Signal vorzusehen; und
    Kombinieren (250) der ersten und zweiten unterdrückten Signale.
  18. Verfahren nach Anspruch 17, wobei Empfangen einer Vielzahl von empfangenen Signalen einen Empfang der Vielzahl von empfangenen Signalen von N räumlich versetzten Mikrofonen umfasst und wobei eine Bearbeitung der Vielzahl von empfangenen Signalen durch einen ersten Filter mit Koeffizienten, die mit einer ersten Quellenraumcharakteristik in Verbindung stehen, um ein erstes gefiltertes Signal vorzusehen, umfasst Bearbeiten der Vielzahl von empfangenen Signalen von jedem der N Mikrofone durch einen zugehörigen von N Filtern umfassend den ersten Filter und Kombinieren von Ausgaben der N Filter umfassend den ersten Filter, um das erste gefilterte Signal vorzusehen, und wobei Bearbeiten der Vielzahl von empfangenen Signalen durch einen zweiten Filter mit Koeffizienten, die mit einer zweiten Quellenraumcharakteristik in Verbindung stehen, um ein zweites gefiltertes Signal vorzusehen, umfasst Bearbeiten der Vielzahl von empfangenen Signalen von jedem der N Mikrofone durch einen zugehörigen von N Filtern umfassend den zweiten Filter und Kombinieren von Ausgaben der N Filter umfassend den zweiten Filter, um das zweite gefilterte Signal vorzusehen.
  19. Verfahren nach Anspruch 18, ferner umfassend eine Bewertung der Koeffizienten der N Filter umfassend den ersten Filter und der N Filter umfassend den zweiten Filter.
  20. Verfahren nach Anspruch 19, ferner umfassend eine Bewertung der Koeffizienten des dritten Filters, der auf einen Beschränkungswert reagiert, der mit der ersten Quelle in Verbindung steht, und eine Bewertung der Koeffizienten des vierten Filters, der auf einen Beschränkungswert reagiert, der mit der zweiten Quelle in Verbindung steht.
  21. Verfahren nach Anspruch 19, wobei eine Bewertung der Koeffizienten der N Filter umfassend den ersten Filter und der N Filter umfassend den zweiten Filter eine Bewertung der Koeffizienten basierend auf der Gleichung umfasst, wobei gN -1(w;ri,rk) Elemente der Matrix gN -1 bezeichnet, die eine Umkehrung der Rauschraumkorrelationsfunktion gN(w;ri, rk) ist, und wobei G(w,rk,Rm) eine Green-Funktion ist, die einen Ausbreitungskanal von einer m-ten Signalquelle mit den Raumkoordinaten Rm beschreibt.
  22. Verfahren nach Anspruch 19, wobei die erste Quelle eine erwünschte Quelle ist und eine Bearbeitung des ersten gefilterten Signals durch einen dritten Filter mit Koeffizienten, die mit einer ausgewählten Unterdrückung für die erste Quelle in Verbindung stehen, um ein erstes unterdrücktes Signal vorzusehen, eine Bearbeitung des ersten gefilterten Signals durch den dritten Filter umfasst, wobei die ausgewählte Unterdrückung, die durch den dritten Filter vorgesehen wird, ungefähr 0 Dezibel ist, und wobei die zweite Quelle eine unerwünschte Quelle ist und eine Bearbeitung des zweiten gefilterten Signals durch einen vierten Filter mit Koeffizienten, die mit einer gewählten Unterdrückung für die zweite Quelle in Verbindung stehen, um ein zweites unterdrücktes Signal vorzusehen, eine Bearbeitung des zweiten gefilterten Signals durch den vierten Filter umfasst, wobei die gewählte Unterdrückung, die durch den vierten Filter vorgesehen wird, mindestens ungefähr -3 Dezibel ist.
EP01904915A 2000-02-29 2001-01-18 Verfahren und systeme für rauschunterdrückung für räumlich versetzte signalquellen Expired - Lifetime EP1261961B1 (de)

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