EP1892703B1 - Verfahren und System zur Bereitstellung eines Tonsignals mit erweiterter Bandbreite - Google Patents

Verfahren und System zur Bereitstellung eines Tonsignals mit erweiterter Bandbreite Download PDF

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EP1892703B1
EP1892703B1 EP06017456A EP06017456A EP1892703B1 EP 1892703 B1 EP1892703 B1 EP 1892703B1 EP 06017456 A EP06017456 A EP 06017456A EP 06017456 A EP06017456 A EP 06017456A EP 1892703 B1 EP1892703 B1 EP 1892703B1
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signal
broadband
bandwidth
bandwidth limit
acoustic signal
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French (fr)
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EP1892703A1 (de
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Tim Haulick
Bernd Iser
Gerhard Schmidt
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Harman Becker Automotive Systems GmbH
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Harman Becker Automotive Systems GmbH
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Priority to DE602006009927T priority Critical patent/DE602006009927D1/de
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Priority to AT06017456T priority patent/ATE446572T1/de
Priority to CA002596411A priority patent/CA2596411A1/en
Priority to JP2007214930A priority patent/JP5150165B2/ja
Priority to KR1020070084306A priority patent/KR101433833B1/ko
Priority to CN2007101466102A priority patent/CN101141533B/zh
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/02—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using spectral analysis, e.g. transform vocoders or subband vocoders
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L21/00—Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
    • G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
    • G10L21/038—Speech enhancement, e.g. noise reduction or echo cancellation using band spreading techniques
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/04—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using predictive techniques
    • G10L19/06—Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/04—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using predictive techniques
    • G10L19/08—Determination or coding of the excitation function; Determination or coding of the long-term prediction parameters
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L2019/0001—Codebooks

Definitions

  • the invention is directed to a method and a system for providing an acoustic signal, in particular a speech signal, with extended bandwidth.
  • Acoustic signals transmitted via an analog or digital signal path usually suffer from the drawback that the signal path only has a restricted bandwidth such that the transmitted acoustic signal differs considerably from the original signal. For example, in the case of conventional telephone connections, a sampling rate of 8 kHz is used resulting in a maximal signal bandwidth of 4 kHz. Compared to the case of audio CD's, the speech and audio quality is significantly reduced.
  • the bandwidth of telephone connections could be increased by using broadband or wideband digital coding and decoding methods (so-called broadband codecs).
  • broadband codecs wideband digital coding and decoding methods
  • both the transmitter and the receiver have to support corresponding coding and decoding methods which would require the implementation of a new standard.
  • systems for bandwidth extension can be used as described, for example, in P. Jax, Enhancement of Bandlimited Speech Signals: Algorithms and Theoretical Bounds, Dissertation, Aachen, Germany, 2002 or E. Larsen, R. M. Aarts, Audio Bandwidth Extension, Wiley, Hoboken, NJ, USA, 2004 .
  • These systems are to be implemented on the receiver's side only such that existing telephone connections do not have to be changed.
  • the missing frequency components of an input signal with small bandwidth are estimated and added to the input signal.
  • Fig. 6 An example of the structure and the corresponding signal flow in such a state of the art bandwidth extension system is illustrated in Fig. 6 .
  • both the lower and the upper frequency ranges are re-synthesized.
  • an incoming or received acoustic signal x ( n ) in digitized form is processed by sub-sampling and block extraction so as to obtain signal vectors x ( n ).
  • the variable n denotes the time.
  • the bandwidth extension is performed only within the missing frequency ranges.
  • the extension concerns low frequency (for example from 0 to 300 Hz) and/or high frequency (for example 3400 Hz to half of the desired sampling rate) ranges.
  • a narrowband spectral envelope is extracted from the narrowband signal, the narrowband signal being restricted by the bandwidth restrictions of the telephone channel.
  • a corresponding broadband envelope signal is estimated from the narrowband envelope.
  • the mappings are based, for example, on codebook pairs (see J. Epps, W. H. Holmes, A New Technique for Wideband Enhancement of Coded Narrowband Speech, IEEE Workshop on Speech Coding, Conference proceedings, pages 174 to 176 June 1999 ) or on Neural Networks (see J.-M. Valin R. Lefebvre, Bandwidth Extension of Narrowband Speech for Low Bit-Rate Wideband Coding, IEEE Workshop on Speech Coding, Conference Proceedings, pages 130 to 132, September 2000 ). In these methods, the entries of the codebooks or the weights of the neural networks are generated using training methods requiring large processor and memory resources.
  • a broadband or wideband excitation signal having a spectrally flat envelope is generated from the narrowband signal.
  • This excitation signal corresponds to the signal which would be recorded directly behind the vocal cords, i.e. the excitation signal contains information about voicing and pitch, but not about form and structures or the spectral shaping in general.
  • the excitation signal has to be weighted with the spectral envelope.
  • non-linear characteristics see U. Kornagel, Spectral Widening of the Excitation Signal for Telephone-Band Speech Enhancement, IWAENC 01, Conference Proceedings, pages 215 to 218, September 2001
  • two-ray rectifying or squaring for example.
  • the excitation signal x exc ( n ) is spectrally colored using the envelope in block 604.
  • the spectral ranges used for the extension are extracted using a band stop filter in block 606 resulting in signal vectors y ext ( n ).
  • the band stop filter can be effective, for example, in the range from 200 to 3700 Hz.
  • the signal vectors x(n) of the received signal are passed through a complementary band pass filter in block 605. Then, the signal components y ext ( n ) and y tel ( n ) are added to obtain a signal vector y ( n ) with extended bandwidth. In block 607, the different signal vectors are assembled again and an over-sampling is performed resulting in a signal y (n).
  • EP 0 944 036 discloses a method and a device for detecting voice sections.
  • a method for speech bandwidth extension is disclosed in US 2002/0138268 .
  • a frequency interpolating device and method is known from EP 1 298 643 .
  • a method for providing an acoustic signal with extended bandwidth comprising:
  • the method according to the invention allows an adaptation of the bandwidth extension to the acoustic signal actually received. For example, when the transmitter uses an ISDN telephone, a broader frequency range is used compared to the case of a mobile phone with a hands-free system. Therefore, the bandwidth of a received acoustic signal will be extended only in those ranges where it is necessary so that the quality of the resulting signal is very high.
  • the received acoustic signal may be a digital signal or may be digitized.
  • steps (a) to (c) may be preceded by the step of converting the received acoustic signal to a predetermined sampling rate.
  • steps (a) to (c) may be preceded by the step of extracting a signal vector from the acoustic signal, in particular, the converted acoustic signal.
  • the signal vector may be obtained by sub-sampling the acoustic signal and may comprise a predefined number of entries. Then, subsequent (in time) signal vectors may overlap. The use of signal vectors simplifies further processing of the signals.
  • Steps (a) to (c) may be preceded by the step of determining a spectral vector of the received acoustic signal.
  • a window function may be applied to signal vectors of the received acoustic signal.
  • a Hann or a Hamming window may be used (see K. D. Kammeyer, K. Kroschel, Digitale Signaltechnik, 4 th Edition, Teubner, Stuttgart, Germany 1997 ).
  • Signal vectors, in particular the signal vectors weighted in this way may be transformed into the Fourier domain using a discrete Fourier transform.
  • the resulting vector is a short-term spectral vector. This allows for further processing in the Fourier domain.
  • step (b) comprises determining a broadband spectral envelope signal and a broadband excitation signal between the lower and upper broadband bandwidth limits such that the product of spectral envelope signal and excitation signal corresponds to the received acoustic signal according to a predetermined criterion.
  • Such a decomposition into an envelope signal and an excitation signal simplifies determining the current bandwidth limits and increases the accuracy when determining a complementary signal.
  • Step (a) comprises comparing a determined broadband spectral envelope signal and a spectrum of the received acoustic signal. It turned out that the spectrum is a suitable basis for determining current bandwidth limits of the acoustic signal.
  • determining a complementary signal in step (b) based on these current bandwidth limits and comprising determination of an envelope signal enables to iteratively adapt the current bandwidth limits by comparing again the (newly) determined envelope signal and a spectrum.
  • determining current bandwidth limits in step (a) may use a spectral envelope signal determined according to step (b), particularly in a preceding step or in a preceding iteration of the method.
  • the comparing step may comprise selecting the minimal and maximal frequency for which the long-term power spectrum is larger than or equal to the determined broadband spectral envelope signal plus a predetermined constant.
  • the predetermined constant can be chosen based on empirical or theoretical data.
  • the predetermined constant may be negative.
  • determining a broadband spectral envelope signal may comprise selecting an envelope signal from a codebook according to a predetermined criterion.
  • codebooks By using codebooks, the required computing power can be reduced for determining an envelope signal.
  • different kinds of criteria can be used when selecting an envelope signal from a codebook.
  • using a predetermined distance criterion such as a cepstral distance can be used, particularly if the codebook entries have the form of cepstral vectors.
  • selecting an envelope signal may comprise equalizing the received acoustic signal and selecting an envelope signal from the codebook having minimal distance to the equalized acoustic signal according to a predetermined distance criterion, in particular, having a minimal cepstral distance.
  • Equalizing the acoustic signal allows to modify it such that a comparison with envelope signals from the codebook can be simplified.
  • the received acoustic signal can be equalized in such a way that the resulting signal shows a long-term power spectrum corresponding to the long-term power spectrum of the signal used for training the codebook.
  • Equalizing can be restricted to frequencies between the current upper and lower bandwidth limits of the received acoustic signal; outside these limits, the signal may remain unchanged.
  • equalizing the received acoustic signal can be performed using a normalized long-term power spectrum of the signal used for training the codebooks, particularly using the normalized long-term power spectrum divided by the normalized long-term power spectrum of the received acoustic signal itself.
  • the codebook may comprise pairs of corresponding envelope signals, each pair comprising a broadband envelope signal between the lower and upper broadband bandwidth limits and a corresponding narrowband envelope signal between a lower narrowband bandwidth limit being larger than the lower broadband bandwidth limit and an upper narrowband bandwidth limit being smaller than the upper broadband bandwidth limit, and selecting an envelope signal may comprise determining a narrowband envelope signal having minimal distance to the equalized acoustic signal according to the predetermined distance criterion and selecting the corresponding broadband envelope signal of this pair.
  • the received acoustic signal When using a cepstral distance to select an envelope signal, the received acoustic signal, particularly in its equalized form, has to be transformed into the cepstral domain.
  • the step of selecting an envelope signal can further comprise the steps of determining the absolute value squared of the sub-band signals of the received acoustic signal, determining an auto-correlation in the time domain, particularly by performing an inverse discrete Fourier transform on the vector of the absolute value squared, determining prediction coefficients, particularly using the Levinson-Durbin algorithm, performing a recursion to obtain the cepstral coefficients.
  • the method may further comprise the steps of recursively transforming a cepstral vector into prediction error coefficients, augmenting the prediction error filter vector by adding a predetermined number of zeros and subsequently performing a discrete Fourier transform to obtain an inverse spectrum, determining the reciprocal of each sub-band component to obtain a spectral envelope vector.
  • the step of selecting an envelope signal may be preceded by providing adapted narrowband codebook envelope signals being adapted to the current lower and upper bandwidth limits.
  • Such an adaptation of the codebook entries allows for an improved selection of a corresponding envelope signal from the codebook.
  • the adaptation would result in envelope signals in the codebook having an extended bandwidth. In this way, particularly fricatives can be more reliably detected.
  • the providing step may comprise processing broadband codebook envelope signals using a long-term power spectrum of the received acoustic signal.
  • the long-term power spectrum may be normalized; furthermore, the long-term power spectrum of the received acoustic signal may be divided by a normalized long-term power spectrum of a broadband signal used for training of the codebook.
  • the processing of the broadband codebook envelope signals may be performed only for frequencies outside the current bandwidth limits; within the bandwidth limits, the envelope signals may remain unchanged.
  • Processing using the long-term power spectrum may comprise weighting broadband codebook envelope signal vectors using the long-term power spectrum of the received acoustic signal.
  • determining a long-term power spectrum may comprise performing a first order recursive smoothing of the absolute values squared of the sub-band signals corresponding to the acoustic signal. This can be done, in particular, only if a wanted signal, such as a speech signal, has been detected in the received acoustic signal.
  • the long-term power spectrum may be normalized, particularly with respect to a long-term power spectrum within predetermined frequency limits.
  • the long-term power spectrum may be determined in the time domain. This can be done by determining the auto-correlation and performing an LPC analysis to obtain corresponding prediction coefficients.
  • determining a broadband excitation signal may be based on prediction error filtering and/or a non-linear characteristic. In this way, suitable excitation signals can be generated. Possible non-linear characteristics are disclosed, for example, in U. Kornagel, Spectral Widening of the Excitation Signal for Telephone-Band Speech Enhancement .
  • the at least one complementary signal may be based on a product of the determined broadband spectral envelope and the determined broadband excitation signal, and step (c) may comprise summing the received acoustic signal between the current lower and upper bandwidth limits and the at least one complementary signal being restricted to the band between the lower broadband bandwidth limit and a current lower bandwidth limit and/or to the band between the current upper bandwidth limit and the upper broadband bandwidth limit.
  • the complementary signal is based on spectrally coloring the excitation signal using the envelope signal.
  • Step (c) may also comprise adapting the power of the complementary signal and/or the received acoustic signal. With this step, the power of the received acoustic signal can be maintained.
  • At least one of the steps may be performed in the cepstral domain. Particularly if the entries of the codebook are cepstral vectors, this allows for performing the method in a simpler way.
  • Steps (a) to (c) of the above methods may be repeated at predetermined time intervals. Then, the repeated adaptation to the currently received acoustic signal leads to a permanent high quality of the resulting broadband signal.
  • Steps (a) to (c) of the above methods may be repeated only if a wanted signal component, such as speech activity, is detected in the received acoustic signal.
  • a wanted signal component such as speech activity
  • an extension of the bandwidth of the received acoustic signal is advantageous.
  • restricting the method to the case of detected speech activity reduces the required computing power and avoids the presence of artifacts due to mal-adaptation.
  • the invention also provides a computer program product comprising one or more computer-readable media having computer-executable instructions for performing the steps of the above-described methods when run on a computer.
  • an apparatus for providing an acoustic signal with extended bandwidth comprising:
  • such an apparatus provides an advantageous way to extend the bandwidth of a received acoustic signal.
  • the quality of the resulting output signal is increased compared to the case of bandwidth extension systems with fixed parameters.
  • the complementary signal means comprises a means for determining a broadband spectral envelope signal and a broadband excitation signal between the lower and upper broadband bandwidth limits such that the product of spectral envelope signal and excitation signal corresponds to the received acoustic signal according to a predetermined criterion.
  • the bandwidth determining means is configured to compare a determined broadband spectral envelope signal and a spectrum of the received acoustic signal.
  • the bandwidth determining means may be configured to select the minimal and maximal frequency for which the spectrum is larger than or equal to the power spectrum of the determined broadband spectral envelope signal plus a predetermined constant.
  • the means for determining a broadband spectral envelope signal may comprise a means for selecting an envelope signal from a codebook according to a predetermined criterion.
  • the means for selecting an envelope signal may be configured to equalize the received acoustic signal and select an envelope signal from the codebook having minimal distance to the equalized acoustic signal according to a predetermined distance criterion, in particular, having a minimal cepstral distance.
  • the codebook may comprise pairs of corresponding envelope signals, each pair comprising a broadband envelope signal between the lower and upper broadband bandwidth limits and a corresponding narrowband envelope signal between a lower narrowband bandwidth limit being larger than the lower broadband bandwidth limit and an upper narrowband bandwidth limit being smaller than the upper broadband bandwidth limit
  • the means for selecting an envelope signal may be configured to determine a narrowband envelope signal having minimal distance to the equalized acoustic signal according to the predetermined distance criterion and to select the corresponding broadband envelope signal of this pair.
  • the means for determining a broadband spectral envelope signal may comprise a means for providing adapted narrowband codebook envelope signals being adapted to the current lower and upper bandwidth limits.
  • the means for providing may be configured to process the broadband codebook envelope signal using a long-term power spectrum of the received acoustic signal.
  • the means for determining a broadband excitation signal may be configured to determine the broadband excitation signal based on prediction error filtering and/or a non-linear characteristic.
  • the at least one complementary signal may be based on a product of the determined broadband spectral envelope and the determined broadband excitation signal, and the assembling means may be configured to sum the received acoustic signal between the current lower and upper bandwidth limits and the at least one complementary signal being restricted to the band between the lower broadband bandwidth limit and a current lower bandwidth limit and/or to the band between the current upper bandwidth limit and the upper broadband bandwidth limit.
  • At least one of the means may be configured to perform at least part of its function in the cepstral domain.
  • the means of the above-described apparatus may be configured to perform their respective function repeatedly at predetermined time intervals.
  • the apparatus may further comprise a wanted signal detector, in particular, a speech detector, and the means may be configured to perform their respective function only if a wanted signal component is detected in the received acoustic signal.
  • a wanted signal detector in particular, a speech detector
  • Fig. 1 shows the structure of the signal flow in an apparatus for providing an acoustic signal with extended bandwidth.
  • Fig. 2 is a flow diagram illustrating an example of a method for providing an acoustic signal with extended bandwidth which could be performed by the apparatus corresponding to Fig. 1 . In view of this, Fig.'s 1 and 2 will be described in the following simultaneously.
  • an acoustic signal such as a speech signal
  • a telephone line Because of the restricted bandwidth of the telephone line, an extension of the bandwidth is desired to improve the signal quality.
  • the signal is to be augmented so as to obtain a predetermined broader bandwidth. It is to be understood that the method described in the following can be used for bandwidth extension independent of the type of incoming signal and independent of the type of transmission line, i.e., it need not be a telephone line.
  • the acoustic signal x(n) received by block 101 has already been pre-processed by increasing the sampling rate up to the predetermined broadband or wideband bandwidth. In this way, however, no additional frequency components are generated. This can be achieved, for example, by using suitable anti-aliasing or anti-imaging filters.
  • This kind of bandwidth extension preferably, is performed only for the "missing" frequency ranges; in the case of an analog telephone line, these ranges may be between 0 and 300 Hz and 3400 Hz up to half of the desired sampling rate, for example, up to 3700 Hz.
  • signal vectors x ( n ) are generated (step 202). This can be achieved by taking every r sampling values up to a certain length.
  • the elements of this matrix can be chosen corresponding to different kinds of windows. Typical windows are the Hann or Hamming window.
  • the resulting short-term spectral vector has the form: X w n [ X e j ⁇ ⁇ 0 ⁇ n , X e j ⁇ ⁇ 1 ⁇ n , ... , X e j ⁇ ⁇ ⁇ ⁇ n , ... , X ⁇ e j ⁇ ⁇ N DFT - 1 ⁇ n ⁇ ] T , wherein ⁇ ⁇ denotes the frequency variable.
  • a long-term power spectrum of the received acoustic signal is determined in block 102 (step 204).
  • 2 diring speech activity S ⁇ xx ⁇ ⁇ ⁇ , n - 1 , else .
  • the time constant ⁇ fre is chosen to be close to 1 (0 ⁇ ⁇ fre ⁇ 1) so as to obtain a sufficiently large averaging time.
  • the recursive smoothing according to the first line of the above equation may be performed continuously. However, in order to avoid any artefacts, it may be performed only if a wanted signal component is present in the received acoustic signal, for example, if speech activity is detected.
  • a speech detector may be provided as described, for example, in E. Hänsler, G. Schmidt, Acoustic Echo and Noise Control - A Practical Approach, Wiley, Hoboken, NJ, USA, 2004 .
  • the band limits ⁇ ⁇ l and ⁇ ⁇ u denote the lower and upper limits of a predefined frequency band.
  • this frequency band may correspond to a telephone band with minimal bandwidth for which the present method is to be used, for example, the limits may be 400 Hz and 3300 Hz.
  • the limits correspond to a band which is smaller or at most equal to the frequency band of the narrow frequency band within which the codebook described below has been trained; these limits being denoted by ⁇ l and ⁇ u .
  • an estimation can be performed in the time domain as well. For this purpose, an auto-correlation is estimated for about 10 to 20 sampling cycles of offset. Afterwards, prediction coefficients can be determined using an LPC (linear predictive coding) analysis.
  • LPC linear predictive coding
  • the acoustic signal is equalized.
  • ⁇ l ( n -1 ) and ⁇ u (n -1) denote the current lower and upper bandwidth limits of the received acoustic signal.
  • the bandwidth limits at time ( n -1) are taken as the current bandwidth limits.
  • S x ⁇ x ⁇ ,norm ( ⁇ ⁇ , n ) denotes the normalized long-term power spectrum of the broadband signal which has been used for training the codebook. Normalizing of such a power spectrum is performed analogously to the case of the long-term power spectrum of the received acoustic signal described above. An example for such a normalized long-term power spectrum used for training a codebook is shown in Figure 3 .
  • the acoustic signal is equalized only within the current bandwidth limits one time step before. Outside these bandwidth limits, no equalizing takes place.
  • An envelope signal corresponding to the received acoustic signal will be determined using a codebook.
  • the used codebook comprises a number of pairs of corresponding narrowband and broadband envelope signals.
  • the codebook has been obtained by training with a large database on the basis of a starting long-term power spectrum (see Y. Linde, A. Buzo, R. M. Gray, An Algorithm for Vector Quantizer Design, IEEE Trans. Comm., vol. COM-28, no. 1, pages 84 - 95, Jan. 1980 ).
  • the codebook entries are adapted in step 206 (block 104).
  • the narrowband codebook entries c i,s ( n ) are adapted.
  • the broadband envelope signals are provided as cepstral vectors c i,b ( n )
  • the corresponding spectra C i,b ( n ) are determined.
  • cepstral vectors are determined from the resulting spectral narrowband envelopes.
  • step 207 The conversion from spectral vectors to cepstral vectors and vice versa will be described in the following with respect to step 207 in which broadband spectral envelopes are determined (block 105).
  • a broadband spectral envelope from the codebook matching the acoustic signal best is determined by comparing the narrowband codebook entries with the spectral envelope of the spectrum of the acoustic signal (after equalizing).
  • the narrowband codebook entry is selected that has the smallness distance to the acoustic signal spectrum. In principle, different distance criteria can be used.
  • the cepstral distance is particularly useful as the codebook entries are provided in the form of cepstral vectors.
  • the corresponding broadband codebook entry is determined as the optimal broadband spectral envelope for the received acoustic signal. Due to the adaptation of the narrowband codebook entries as described above, an optimal narrowband envelope can be selected in a very reliable way.
  • Converting a spectral vector, particularly of the received acoustic signal, to a cepstral vector can be achieved by:
  • the optimal cepstral vector of the broadband codebook is designated by c opt,b ( n ).
  • Fig. 4 illustrates an example of a codebook with four pairs of entries.
  • a corresponding original narrowband envelope, and a corresponding adapted narrowband envelope are shown.
  • the original broadband and narrowband codebook entries have been obtained on the basis of a large database for an ISDN telephone connection.
  • the resulting optimized entries have a higher upper limit frequency. This allows for an improved detection of fricatives.
  • step 208 an excitation signal corresponding to the received acoustic signal is generated.
  • This broadband excitation signal shows a spectrally flat envelope. It corresponds to a signal which would be recorded directly behind the vocal cords.
  • the spectral envelope of the equalized short-term spectrum X eq ( n ) is estimated in the form of prediction error filter coefficients. Applying an inverse discrete Fourier transform on this spectral vector allows to determine the corresponding time signal. After that, the vector in the time domain is filtered by a prediction error filter. The corresponding filter coefficients are those that have been determined previously.
  • a non-linear characteristic such as a two-way rectification or squaring, is applied to the filtered time domain vector. This generates the missing low frequency and high frequency signal components.
  • a transformation in the Fourier domain provides, then, the spectrum of the extended excitation signal X exc ( n ) .
  • determining an excitation signal can be performed in the time sub-band or Fourier domain as well. Examples for this alternative can be found in B. Iser, G. Schmidt, Bandwidth Extension of Telephony Speech, Eurasip Newsletter, Volume 16, Number 2, pages 2 to 24, June 2005 .
  • 2 ⁇ ⁇ ⁇ l ⁇ u Y erw ( e j ⁇ ⁇ ⁇ , n ⁇ ) 2 wherein ⁇ ⁇ l and ⁇ ⁇ u denote the same bandwidth limits as in the estimation of the long-term power spectrum above.
  • the current bandwidth limits are adapted in step 210 (block 108).
  • 2 ⁇ C opt , b ⁇ e j ⁇ ⁇ ⁇ , n 2 + K C , ⁇ u n min ⁇ ⁇ ⁇
  • Fig. 5 an example for determining the bandwidth limits is illustrated.
  • the above, intermediate limit values are given by the points of intersection between the lowered broadband spectral envelope and the spectrum of the received acoustic signal.
  • These intermediate limit values may be recursively smoothed to eliminate temporary mal-estimations.
  • smoothing is performed only if speech activity is detected in the current signal frame.
  • the received acoustic signal is passed through an adaptive band pass filter to retain only components within the current bandwidth limits (block 109) to obtain a spectral vector Y tel ( n ).
  • the spectrally colored excitation signal is passed through a complementary adaptive band stop filter (block 110) so as to obtain a vector Y ext ( n ).
  • Y tel n G tel n ⁇ X w n
  • Y ext n G ext n ⁇ X ext n
  • the weighting matrices G tel ( n ) and G ext ( n ) are diagonal matrices:
  • G tel n G tel e j ⁇ ⁇ 0 ⁇ n 0 ... 0 0
  • G ext n G ext e j ⁇ ⁇ 0 ⁇ n 0 ... 0 0
  • the transitions at the bandwidth limits can be realized in a smoother way.
  • the resulting time domain vectors are, then, assembled using an overlap add method (as described in K. D. Kammeyer, K. Kroschel, Digitale Signalmaschine ) to obtain the final output signal y ( n ).
  • the steps performed in the Fourier domain may also be performed in the time domain.
  • equalizing the acoustic signal may be performed when adapting the narrowband codebook entries.
  • the above-described equalizing step may be augmented. For example, if an amplification or an attenuation is detected at particular frequencies, it may be adjusted within the bandwidth limits as well. In this case, the output vector Y tel ( n ) is modified with the weighting matrix H mod ( n ).

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Claims (23)

  1. Verfahren zum Bereitstellen eines akustischen Signals mit erweiterter Bandbreite, das umfasst:
    (a) automatisches Bestimmen einer aktuellen oberen und aktuellen unteren Bandbreitengrenze eines empfangenen akustischen Signals,
    (b) automatisches Bestimmen wenigstens eines Komplementärsignals, das das empfangene akustische Signal ergänzt, zwischen einer vordefinierten unteren Breitband-Bandbreitengrenze und der aktuellen unteren Bandbreitengrenze und/oder zwischen der aktuellen oberen Bandbreiten-Grenze und einer vordefinierten oberen Breitband-Bandbreitengrenze, wobei die vordefinierte untere Breitband-Bandbreitengrenze niedriger ist als die aktuelle untere Bandbreitengrenze, und die vordefinierte obere Breitband-Bandbreitengrenze höher ist als die aktuelle obere Bandbreitengrenze,
    (c) automatisches Zusammensetzen des wenigstens einen Komplementärsignals und des empfangenen akustischen Signals, um ein akustisches Signal mit erweiterter Bandbreite zu gewinnen,
    wobei Schritt (b) umfasst, dass ein Breitband-Spektral-Hüllkurvensignal und ein Breitband-Erregungssignal zwischen der unteren und der oberen Breitband-Bandbreitengrenze so bestimmt werden, dass das Produkt des Spektral-Hüllkurvensignals und des Erregungssignals dem empfangenen akustischen Signal gemäß einem vorgegebenen Kriterium entspricht; und
    wobei Schritt (a) Vergleichen des bestimmten Breitband-Spektral-Hüllkurvensignals und eines Spektrums des empfangenen akustischen Signals umfasst, so dass die aktuelle obere und die aktuelle untere Bandbreitengrenze iterativ angepasst werden, wobei der Vergleichsschritt Auswählen der minimalen und maximalen Frequenz umfasst, für die das Spektrum größer ist als oder genauso groß wie das bestimmte Breitband-Spektral-Hüllkurvensignal zuzüglich einer vorgegebenen Konstante.
  2. Verfahren nach Anspruch 1, wobei Bestimmen eines Breitband-Spektral-Hüllkurvensignals Auswählen eines Hüllkurvensignals aus einem Codebuch gemäß einem vorgegebenen Kriterium umfasst.
  3. Verfahren nach Anspruch 2, wobei Auswählen eines Hüllkurvensignals Entzerren des empfangenen akustischen Signals und Auswählen eines Hüllkurvensignals aus dem Codebuch umfasst, das gemäß einem vorgegebenen Distanz-Kriterium minimale Distanz zu dem entzerrten akustischen Signal, insbesondere eine minimale cepstrale Distanz, hat.
  4. Verfahren nach Anspruch 3, wobei das Codebuch Paare entsprechender Hüllkurvensignale umfasst, wobei jedes Paar ein Breitband-Hüllkurvensignal zwischen der unteren und der oberen Breitband-Bandbreitengrenze sowie ein entsprechendes Schmalband-Hüllkurvensignal zwischen einer unteren Schmalband-Bandbreitengrenze umfasst, die höher ist als die untere Breitband-Bandbreitengrenze, und einer oberen Schmalband-Bandbreitengrenze umfasst, die niedriger ist als die obere Breitband-Bandbreitengrenze, und Auswählen eines Hüllkurvensignals Bestimmen eines Schmalband-Hüllkurvensignals, das gemäß dem vorgegebenen Distanz-Kriterium minimale Distanz zu dem entzerrten akustischen Signal hat, sowie Auswählen des entsprechenden Breitband-Hüllkurvensignals dieses Paars umfasst.
  5. Verfahren nach Anspruch 4, wobei dem Schritt des Auswählens eines Hüllkurvensignals Bereitstellen angepasster Schmalband-Codebuch-Hüllkurvensignale vorangeht, die an die aktuelle untere und obere Bandbreitengrenze angepasst sind.
  6. Verfahren nach Anspruch 5, wobei der Schritt des Bereitstellens Verarbeiten von Breitband-Codebuch-Hüllkurvensignalen unter Verwendung eines Langzeit-Leistungsspektrums des empfangenen akustischen Signals umfasst.
  7. Verfahren nach einem der Ansprüche 1-6, wobei Bestimmen eines Breitband-Erregungssignals auf Prädiktions-Fehlerfilterung und/oder einer nicht linearen Charakteristik basiert.
  8. Verfahren nach einem der Ansprüche 1-7, wobei das wenigstens eine Komplementärsignal auf einem Produkt der bestimmten Breitband-Spektral-Hüllkurve und des bestimmten Breitband-Erregungssignals basiert und Schritt (c) Summieren des empfangenen akustischen Signals zwischen der aktuellen unteren und oberen Bandbreiten-Grenze und des wenigstens einen Komplementärsignals umfasst, das auf das Band zwischen der unteren Breitband-Bandbreitengrenze und einer aktuellen unteren Bandbreitengrenze und/oder auf das Band zwischen der aktuellen oberen Bandbreitengrenze und der oberen Breitband-Bandbreitengrenze beschränkt ist.
  9. Verfahren nach einem der vorangehenden Ansprüche, wobei wenigstens einer der Schritte in der cepstralen Domäne durchgeführt wird.
  10. Verfahren nach einem der vorangehenden Ansprüche, wobei die Schritte (a) bis (c) in vorgegebenen Zeitintervallen wiederholt werden.
  11. Verfahren nach einem der vorangehenden Ansprüche, wobei die Schritte (a) bis (c) nur wiederholt werden, wenn eine erwünschte Signalkomponente, insbesondere Sprachaktivität, in dem empfangenen akustischen Signal erfasst wird.
  12. Computerprogrammerzeugnis, das ein oder mehrere computerlesbare Medium/Medien umfasst, das/die durch Computer ausführbare Befehle zum Durchführen der Schritte des Verfahrens nach einem der vorangehenden Ansprüche bei Ausführung auf einem Computer umfasst/umfassen.
  13. Vorrichtung zum Bereitstellen eines akustischen Signals mit erweiterter Bandbreite, die umfasst:
    eine Bandbreiten-Bestimmungseinrichtung zum automatischen Bestimmen einer aktuellen oberen und einer aktuellen unteren Bandbreitengrenze eines empfangenen akustischen Signals,
    eine Komplementärsignal-Einrichtung zum automatischen Bestimmen wenigstens eines Komplementärsignals, das das akustische Signal ergänzt, zwischen einer vordefinierten unteren Breitband-Bandbreitengrenze und der aktuellen unteren Bandbreitengrenze und/oder zwischen der aktuellen oberen Bandbreitengrenze und einer vordefinierten oberen Breitband-Bandbreitengrenze, wobei die vordefinierte untere Breitband-Bandbreitengrenze niedriger ist als die aktuelle untere Bandbreitengrenze und die vordefinierte obere Breitband-Bandbreitengrenze höher ist als die aktuelle obere Bandbreitengrenze, und
    eine Zusammensetzeinrichtung zum automatischen Zusammensetzen des wenigstens einen Komplementärsignals und des empfangenen akustischen Signals, um ein akustisches Signal mit erweiteter Bandbreite zu gewinnen,
    wobei die Komplementärsignal-Einrichtung eine Einrichtung umfasst, mit der ein Breitband-Spektral-Hüllkurvensignal und ein Breitband-Erregungssignal zwischen der unteren und der oberen Breitband-Bandbreitengrenze so bestimmt werden, dass das Produkt des Spektral-Hüllkurvensignals und des Erregungssignals dem empfangenen akustischen Signal gemäß einem vorgegebenen Kriterium entspricht,
    wobei die Bandbreiten-Bestimmungseinrichtung so konfiguriert ist, dass sie das bestimmte Breitband-Spektral-Hüllkurvensignal und ein Spektrum des empfangenen akustischen Signals vergleicht, so dass die aktuelle obere und die aktuelle untere Bandbreitengrenze iterativ angepasst werden, und wobei die Bandbreiten-Bestimmungseinrichtung so konfiguriert ist, dass sie die minimale und maximale Frequenz auswählt, für die das Spektrum größer ist als oder genauso groß wie das bestimmte Breitband-Spektral-Hüllkurvensignal zuzüglich einer vorgegebenen Konstante.
  14. Vorrichtung nach Anspruch 13, wobei die Einrichtung, mit der ein Breitband-Spektral-Hüllkurvensignal bestimmt wird, eine Einrichtung zum Auswählen eines Hüllkurvensignals aus einem Codebuch gemäß einem vorgegebenen Kriterium umfasst.
  15. Vorrichtung nach Anspruch 14, wobei die Einrichtung zum Auswählen eines Hüllkurvensignals so konfiguriert ist, dass sie das empfangene akustische Signal entzerrt und ein Hüllkurvensignal aus dem Codebuch auswählt, das gemäß einem vorgegebenen Distanz-Kriterium minimale Distanz zu dem entzerrten akustischen Signal, insbesondere eine minimale cepstrale Distanz, hat.
  16. Vorrichtung nach Anspruch 15, wobei das Codebuch Paare entsprechender Hüllkurvensignale umfasst und jedes Paar ein Breitband-Hüllkurvensignal zwischen der unteren und der oberen Bandbreitengrenze sowie ein entsprechendes Schmalband-Hüllkurvensignal zwischen einer unteren Schmalband-Bandbreitengrenze, die höher ist als die untere Breitband-Bandbreitengrenze, und einer oberen Schmalband-Bandbreitengrenze umfasst, die niedriger ist als die obere Breitband-Bandbreitengrenze, und die Einrichtung zum Auswählen eines Hüllkurvensignals so konfiguriert ist, dass sie ein Schmalband-Hüllkurvensignal bestimmt, das gemäß dem vorgegebenen Distanz-Kriterium minimale Distanz zu dem entzerrten akustischen Signal hat, und das entsprechende Breitband-Hüllkurvensignal dieses Paars auswählt.
  17. Vorrichtung nach Anspruch 16, wobei die Einrichtung zum Bestimmen eines Breitband-Spektral-Hüllkurvensignals eine Einrichtung zum Bereitstellen angepasster Schmalband-Codebuch-Hüllkurvensignale umfasst, die an die aktuelle untere und obere Bandbreitengrenze angepasst sind.
  18. Vorrichtung nach Anspruch 17, wobei die Einrichtung zum Erzeugen so konfiguriert ist, dass sie das Breitband-Codebuch-Hüllkurvensignal unter Verwendung eines Langzeit-Leistungsspektrums des empfangenen akustischen Signals verarbeitet.
  19. Vorrichtung nach einem der Ansprüche 13-18, wobei die Einrichtung zum Bestimmen eines Breitband-Erregungssignals so konfiguriert ist, dass sie das Breitband-Erregungssignal auf Basis von Prädiktions-Fehlerfilterung und/oder einer nicht linearen Charakteristik bestimmt.
  20. Vorrichtung nach einem der Ansprüche 13-19, wobei das wenigstens eine Komplementärsignal auf einem Produkt der bestimmten Breitband-Spektral-Hüllkurve und des bestimmten Breitband-Erregungssignals basiert und die Zusammensetzeinrichtung so konfiguriert ist, dass sie das empfangene akustische Signal zwischen der aktuellen unteren und oberen Bandbreitengrenze und das wenigstens eine Komplementärsignal summiert, das auf das Band zwischen der unteren Breitband-Bandbreitengrenze und einer aktuellen unteren Bandbreitengrenze und/oder das Band zwischen der aktuellen oberen Bandbreitengrenze und der oberen Breitband-Bandbreitengrenze beschränkt ist.
  21. Vorrichtung nach einem der Ansprüche 13-20, wobei wenigstens eine der Einrichtungen so konfiguriert ist, dass sie wenigstens einen Teil ihrer Funktion in der cepstralen Domäne erfüllt.
  22. Vorrichtung nach einem der Ansprüche 13-21, wobei die Einrichtungen so konfiguriert sind, dass sie ihre Funktion wiederholt in vorgegebenen Zeitintervallen erfüllen.
  23. Vorrichtung nach einem der Ansprüche 13-22, die des Weiteren einen Detektor für ein erwünschtes Signal, insbesondere einen Sprachdetektor, umfasst, und wobei die Einrichtungen so konfiguriert sind, dass sie ihre jeweilige Funktion nur erfüllen, wenn eine erwünschte Signalkomponente in dem empfangenen akustischen Signal erfasst wird.
EP06017456A 2006-08-22 2006-08-22 Verfahren und System zur Bereitstellung eines Tonsignals mit erweiterter Bandbreite Not-in-force EP1892703B1 (de)

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DE602006009927T DE602006009927D1 (de) 2006-08-22 2006-08-22 Verfahren und System zur Bereitstellung eines Tonsignals mit erweiterter Bandbreite
EP06017456A EP1892703B1 (de) 2006-08-22 2006-08-22 Verfahren und System zur Bereitstellung eines Tonsignals mit erweiterter Bandbreite
AT06017456T ATE446572T1 (de) 2006-08-22 2006-08-22 Verfahren und system zur bereitstellung eines tonsignals mit erweiterter bandbreite
CA002596411A CA2596411A1 (en) 2006-08-22 2007-08-08 Method and system for providing an acoustic signal with extended bandwidth
JP2007214930A JP5150165B2 (ja) 2006-08-22 2007-08-21 拡張された帯域幅を有する音響信号を提供するための方法およびシステム
KR1020070084306A KR101433833B1 (ko) 2006-08-22 2007-08-22 음향 신호에 확장된 대역폭을 제공하기 위한 방법 및시스템
CN2007101466102A CN101141533B (zh) 2006-08-22 2007-08-22 用于提供具有扩展带宽的声音信号的方法和系统

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8433582B2 (en) 2008-02-01 2013-04-30 Motorola Mobility Llc Method and apparatus for estimating high-band energy in a bandwidth extension system
US8463599B2 (en) 2009-02-04 2013-06-11 Motorola Mobility Llc Bandwidth extension method and apparatus for a modified discrete cosine transform audio coder
US8688441B2 (en) 2007-11-29 2014-04-01 Motorola Mobility Llc Method and apparatus to facilitate provision and use of an energy value to determine a spectral envelope shape for out-of-signal bandwidth content

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090201983A1 (en) 2008-02-07 2009-08-13 Motorola, Inc. Method and apparatus for estimating high-band energy in a bandwidth extension system
US8463412B2 (en) 2008-08-21 2013-06-11 Motorola Mobility Llc Method and apparatus to facilitate determining signal bounding frequencies
JP2010079275A (ja) * 2008-08-29 2010-04-08 Sony Corp 周波数帯域拡大装置及び方法、符号化装置及び方法、復号化装置及び方法、並びにプログラム
US8706497B2 (en) 2009-12-28 2014-04-22 Mitsubishi Electric Corporation Speech signal restoration device and speech signal restoration method
CN102870156B (zh) * 2010-04-12 2015-07-22 飞思卡尔半导体公司 音频通信设备、输出音频信号的方法和通信系统
CA2961336C (en) * 2013-01-29 2021-09-28 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Audio encoders, audio decoders, systems, methods and computer programs using an increased temporal resolution in temporal proximity of onsets or offsets of fricatives or affricates
US10121487B2 (en) 2016-11-18 2018-11-06 Samsung Electronics Co., Ltd. Signaling processor capable of generating and synthesizing high frequency recover signal
CN107404625B (zh) * 2017-07-18 2020-10-16 海信视像科技股份有限公司 终端的音效处理方法及装置
KR102093819B1 (ko) * 2018-09-10 2020-03-26 한국과학기술연구원 음원 분리 장치 및 방법

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3483958B2 (ja) * 1994-10-28 2004-01-06 三菱電機株式会社 広帯域音声復元装置及び広帯域音声復元方法及び音声伝送システム及び音声伝送方法
EP1944753A3 (de) 1997-04-30 2012-08-15 Nippon Hoso Kyokai Verfahren und Vorrichtung zur Erkennung von Stimmabschnitten und Verfahren zur Umwandlung der Sprechgeschwindigkeit mit diesem Verfahren und Vorrichtung
US6539355B1 (en) * 1998-10-15 2003-03-25 Sony Corporation Signal band expanding method and apparatus and signal synthesis method and apparatus
US6836739B2 (en) 2000-06-14 2004-12-28 Kabushiki Kaisha Kenwood Frequency interpolating device and frequency interpolating method
JP3713200B2 (ja) * 2000-11-30 2005-11-02 株式会社ケンウッド 信号補間装置、信号補間方法及び記録媒体
US6889182B2 (en) 2001-01-12 2005-05-03 Telefonaktiebolaget L M Ericsson (Publ) Speech bandwidth extension
JP4012506B2 (ja) * 2001-08-24 2007-11-21 株式会社ケンウッド 信号の周波数成分を適応的に補間するための装置および方法
EP1430475A1 (de) * 2001-08-31 2004-06-23 Koninklijke Philips Electronics N.V. Bandbreitenerweiterung eines klangsignals
JP4281349B2 (ja) * 2001-12-25 2009-06-17 パナソニック株式会社 電話装置
WO2005055645A1 (en) * 2003-12-01 2005-06-16 Koninklijke Philips Electronics N.V. Selective audio signal enhancement
EP1719117A1 (de) * 2004-02-16 2006-11-08 Koninklijke Philips Electronics N.V. Transcodierer und transcodierungsverfahren dafür
EP1638083B1 (de) 2004-09-17 2009-04-22 Harman Becker Automotive Systems GmbH Bandbreitenerweiterung von bandbegrenzten Tonsignalen

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8688441B2 (en) 2007-11-29 2014-04-01 Motorola Mobility Llc Method and apparatus to facilitate provision and use of an energy value to determine a spectral envelope shape for out-of-signal bandwidth content
US8433582B2 (en) 2008-02-01 2013-04-30 Motorola Mobility Llc Method and apparatus for estimating high-band energy in a bandwidth extension system
US8463599B2 (en) 2009-02-04 2013-06-11 Motorola Mobility Llc Bandwidth extension method and apparatus for a modified discrete cosine transform audio coder

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