WO2008135887A1 - Système de rendu sonore stéréo - Google Patents

Système de rendu sonore stéréo Download PDF

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Publication number
WO2008135887A1
WO2008135887A1 PCT/IB2008/051606 IB2008051606W WO2008135887A1 WO 2008135887 A1 WO2008135887 A1 WO 2008135887A1 IB 2008051606 W IB2008051606 W IB 2008051606W WO 2008135887 A1 WO2008135887 A1 WO 2008135887A1
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WO
WIPO (PCT)
Prior art keywords
array
sound
width
stereo
loudspeakers
Prior art date
Application number
PCT/IB2008/051606
Other languages
English (en)
Inventor
Werner P. J. De Bruijn
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2008135887A1 publication Critical patent/WO2008135887A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/12—Circuits for transducers, loudspeakers or microphones for distributing signals to two or more loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S7/00—Indicating arrangements; Control arrangements, e.g. balance control
    • H04S7/30—Control circuits for electronic adaptation of the sound field
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2430/00—Signal processing covered by H04R, not provided for in its groups
    • H04R2430/20—Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic

Definitions

  • An aspect of the invention relates to a stereo sound rendering system, which comprises an array of loudspeakers.
  • the stereo sound rendering system may be in the form of, for example, a display device with a single loudspeaker unit in the form of a substantially horizontally oriented array of relatively small loudspeakers.
  • Other aspects of the invention relates to a method of stereo sound rendering and a computer program product.
  • a beam- forming driver causes the array of loudspeakers to produce a pair of relatively narrow sound beams.
  • One of these sound beams is directed so that this sound beam reaches the listener by reflection against a side wall, which is left to the listener.
  • the other sound beam is directed so that this sound beam reaches the listener by reflection against another side wall, which is right to the listener.
  • the one and the other sound beam thus constitute a left and a right sound beam.
  • the listener will perceive these sound beams as originating from a phantom left loudspeaker and a phantom right loudspeaker, respectively.
  • the listener will thus perceive a stereo field, which has a given width. This width will be referred to as stereo width hereinafter, wherever appropriate.
  • US patent application published under number 2004/0151325 discloses an apparatus that makes several replicas of an input signal. Each of the replicas is modified before these are routed to respective output transducers such that a desired sound field is created.
  • This sound field may comprise a directed beam, a focused beam, or a simulated origin.
  • the independent claims define various aspects of the invention.
  • the dependent claims define additional features for implementing the invention to advantage.
  • the invention takes the following points into consideration.
  • the listener may perceive the stereo field as unnatural because the stereo width is too large. This is particularly true if the listener is relatively close to the array of loudspeakers.
  • the phantom left loudspeaker and the phantom right loudspeaker will generally appear to be located relatively far from each other.
  • the stereo width which the listener perceives, can be reduced if he or she moves to a location that is relatively distant from the loudspeaker array. However, this may not be practical, or may even not be possible, for reasons of room geometry, or because of furniture that is present in a room, or for other reasons.
  • a beam- forming driver which causes an array of loudspeakers to produce a pair of sound beams for stereo sound rendering, each sound beam having a particular width, is made to adjust the width of at least one of the aforementioned sound beams in response to a stereo width command.
  • a sound beam which may be left-directed or right-directed, can be made relatively wide so that a portion of the sound beam concerned reaches a listener directly, whereas another portion reaches the listener by reflection against a side wall.
  • a phantom loudspeaker which is associated with the sound beam concerned, will have a location that depends on a ratio between these respective portions. The ratio between the respective portions depends on the width of the sound beam concerned.
  • the stereo width can be increased or decreased by decreasing or increasing, respectively, the width of the sound beam concerned.
  • the invention will thus allow the listener to control the stereo width so that he or she perceives a natural stereo sound rendering. For those reasons, the invention allows a pleasant listening experience.
  • the stereo width could be reduced by generating a pair of additional sound beams, which are directed towards the listener.
  • the pair of additional sound beams needs to be generated independently from the earlier mentioned pair of sound beams for stereo sound rendering. Accordingly, such a solution will require relatively complicated hardware or software, or both.
  • generating additional sound beams generally entails a dynamic range reduction.
  • the invention does not require any additional sound beams for the purpose of stereo width control. Consequently, the invention allows cost-efficient implementations that provide a relatively high dynamic range.
  • An implementation of the invention advantageously comprises one or more of following additional features, which are described in separate paragraphs that correspond with individual dependent claims.
  • the beam- forming driver preferably comprises a left beam former, a right beam former, and an array of combiners.
  • the left beam former provides an array of left driver components in response to a left channel signal. Each left driver component is associated with a particular loudspeaker in the array of loudspeakers.
  • the right beam former provides an array of right driver components in response to a right channel signal. Each right driver component is associated with a particular loudspeaker in the array of loudspeakers.
  • Each combiner is associated with a particular loudspeaker in the array of loudspeakers so as to combine the left driver component and the right driver component, which are associated with the same particular loudspeaker.
  • the left beam former may comprise an array of delay stages for imposing respective delays between the respective left driver components.
  • the right beam former comprises an array of delay stages for imposing respective delays between the respective right driver components.
  • the controller preferably adjusts the respective delays in the left beam former and the respective delays in the right beam former on the basis of the stereo width command.
  • the respective delays which are imposed between respective driver components so as to cause the array of loudspeakers to form a sound beam, may define a focal point of the sound beam.
  • the controller may then shift the focal point by adjusting the respective delays.
  • the left beam former may comprise an array of filters for providing respective impulse responses between a point where the left channel signal is present and the respective loudspeakers in the array of loudspeakers.
  • the right beam former may comprise an array of filters for providing respective impulse responses between a point where the right channel signal is present and the respective loudspeakers in the array of loudspeakers.
  • the controller preferably adjusts the respective impulse responses that the array of filters in the left beam former provides, and the respective impulse responses that the array of filters in the right beam former provides, on the basis of the stereo width command.
  • the controller preferably comprises a setup program for acquiring parameters relating to a distance between the listener and the array of loudspeakers and respective distances between the array of loudspeakers and respective walls against which the respective sound beams may reflect.
  • the controller preferably comprises a master controller module, a left beam control module, and a right beam control module.
  • the master control module generates a left beam width command and a right beam width command on the basis of the stereo width command.
  • the left beam control module causes the left beam former to adjust the width of the sound beam that is left-directed on the basis of the left beam width command.
  • the right beam control module causes the right beam former to adjust the width of the sound beam that is right-directed on the basis of the right beam width command.
  • FIG. 1 is a conceptual diagram that illustrates an audiovisual system, which is located in a room.
  • FIG. 2 is a block diagram that illustrates an audio portion of the audiovisual system.
  • FIG. 3 is a block diagram that illustrates a multi-beam forming driver, which forms part of the audiovisual system.
  • FIG. 4 is a block diagram that illustrates a front left beam former, which forms part of the multi-beam forming driver.
  • FIG. 5 is a flow chart diagram that illustrates a series of steps for controlling a perceived stereo width, which steps are carried out in the audiovisual system.
  • FIGS. 6 and 7 are conceptual diagrams that illustrate a beam width control, which causes a change in the perceived stereo width.
  • FIGS. 8, 9 and 10 are conceptual diagrams that illustrate a principal of beam width control by means of displacing a focal point.
  • FIG. 1 illustrates a room RO with an audiovisual system AVS.
  • a listener LI is sitting in front of the audiovisual system AVS.
  • the audiovisual system AVS renders a multimedia content, which comprises an audio signal.
  • the audiovisual system AVS produces five relatively narrow sound beams CTB, FLB, FRB, RLB, RRB, each of which has a particular direction as illustrated in FIG. 1.
  • a center sound beam CTB is directed towards the listener LI.
  • a front left sound beam FLB is directed towards a left wall WL so that the front left sound beam FLB reaches the listener LI via reflection against the left wall WL.
  • a front right sound beam FRB is directed towards a right wall WR so that the front right sound beam FRB reaches the listener LI via reflection against the right wall WR.
  • a rear left sound beam RLB is directed towards the left wall WL so that the rear left sound beam RLB reaches the listener LI via reflection against the left wall WL and subsequent reflection against a rear wall WX.
  • a rear right sound beam RRB is directed towards the rear wall WX so that the rear right sound beam RRB reaches the listener LI via reflection against the right wall WR and subsequent reflection against the rear wall WX.
  • the rear left sound beam RLB and the rear right sound beam RRB produce a surround sound effect.
  • the front left sound beam FLB and the front right sound beam FRB produce a so-called stereo field.
  • the listener LI perceives the front left sound beam FLB as coming from a phantom left loudspeaker PL, which is located outside the room RO, as illustrated in FIG. 1.
  • the phantom left loudspeaker PL has a location that corresponds with that of a mirror image of the audiovisual system AVS as if a mirror were present in the left wall WL.
  • the listener LI perceives the phantom left loudspeaker PL as being placed at a distance from the audiovisual system AVS that is approximately twice the distance between the audiovisual system AVS and the left wall WL.
  • the listener LI perceives the front right sound beam FRB as coming from a phantom right loudspeaker PR, which is located outside the room RO, as illustrated in FIG. 1.
  • the stereo field has a width that depends on the respective locations of the phantom left loudspeaker PL and the phantom right loudspeaker PR with respect to the listener LI.
  • the width of stereo field will be referred to as stereo width hereinafter, wherever appropriate.
  • stereo loudspeakers should be placed so that there is an angle of approximately 60° between the stereo loudspeakers at a listening location. In that case, a natural stereo width is obtained, which is neither too large, nor too narrow.
  • the stereo width there are two parameters that determine the stereo width: firstly, the distance between the left wall WL and the right wall WR and, secondly, the distance between the listener LI and the audiovisual system AVS.
  • the stereo width will be too large and therefore unnatural.
  • the listener LI may not be able to sit at an ideal location in terms of stereo width because of, for example, furniture that is present in the room RO or other practical constraints.
  • the invention provides a cost efficient solution that allows the listener LI to experience a natural stereo width at a great variety of locations.
  • FIG. 2 illustrates an audio portion of the audiovisual system AVS.
  • the audiovisual system AVS comprises the following functional entities: an audio channel processor ACP, a multi-beam forming driver MBD, a loudspeaker array LSA, a master control module CTM, and a remote-control device RCD.
  • the loudspeaker array LSA may comprise, for example, 7 individual loudspeakers arranged in line.
  • the audio channel processor ACP and the multi-beam forming driver MBD may be implemented by means of, for example, one or more dedicated integrated circuits.
  • the aforementioned functional entities may also be implemented by means of a general-purpose processor that a suitably programmed.
  • the master control module CTM may take the form of a software program that is running on a processor.
  • the audio channel processor ACP receives an input audio signal AU, which comprises various different audio channels for stereo surround sound rendering.
  • the audio channel processor ACP derives a set of audio channel signals FLC, RLC, CTC, RRC, FRC from the audio input signal AU.
  • Each audio channel signal corresponds with a particular sound beam illustrated in FIG. 1.
  • the audio channel processor ACP provides a front left channel signal FLC, a rear left channel signal RLC, a center channel signal CTC, a rear right channel signal RRC, and a front right channel signal FRC.
  • the multi-beam forming driver MBD generates an array of driver signals Dl-
  • D7 for the loudspeaker array LSA on the basis of the set of audio channel signals FLC, RLC, CTC, RRC, FRC, which the audio channel processor ACP provides. There is an individual driver signal for each individual loudspeaker in the loudspeaker array LSA.
  • the array of driver signals D1-D7 causes the loudspeaker array LSA to produce the five relatively narrow sound beams CTB, FLB, FRB, RLB, RRB, which are illustrated in FIG. 1.
  • each sound beam has a direction and a width that depends on the beam control data CD.
  • the width of a sound beam can be expressed in terms of, for example, an angle over which a given percentage of acoustical energy is concentrated.
  • the width of a sound beam can also be expressed in terms of a length over which a given percentage of acoustic energy is concentrated at a given distance from the loudspeaker array LSA.
  • FIG. 3 illustrates the multi-beam forming driver MBD.
  • the multi-beam forming driver MBD comprises a front left beam former FLBF, a front right beam former FRBF, an array of combiners CMB1-CMB7, and an array of amplifiers AMP1-AMP7. There is a combiner and an amplifier for each loudspeaker in the loudspeaker array LSA illustrated in FIG. 2.
  • the multi-beam forming driver MBD further comprises the following functional entities, which are not shown in FIG. 3: a rear left beam former, a center beam former, and a rear right beam former.
  • the front left beam former FLBF generates an array of front left driver components S1 FL-S7 FL on the basis of the front left channel signal FLC, which the audio channel processor ACP provides. There is an individual front left driver component for each loudspeaker in the loudspeakers array LSA.
  • the array of front left driver components Sl FL- S7 FL causes the loudspeakers array LSA to produce the front left sound beam FLB, which is illustrated in FIG. 1.
  • the front right beam former FRBF generates an array of front right driver components S1 FR-S7 FR on the basis of the front right channel signal FRC.
  • the array of front right driver components S1 FR-S7 FR causes the loudspeakers array LSA to produce the front right sound beam FRB.
  • the rear left beam former, the center beam former, and the rear right beam former provide an array of rear left driver components, an array of center driver components, and an array of rear right driver components.
  • Combiner CMB 1 provides a combination of driver components S 1 by combining front left driver component Sl FL, front right driver component Sl FR, rear left driver component Sl RL, center driver component Sl CT, and rear right driver component Sl RR.
  • Amplifier AMPl produces driver signal Dl by amplifying this combination of driver components S 1.
  • combiner CMB7 provides a combination of driver components by combining front left driver component S7 FL, front right driver component S7 FR, rear left driver component S7 RL, center driver component S7 CT, and rear right driver component S7 RR.
  • Amplifier AMP7 produces driver signal D7 by amplifying this combination of driver components S7.
  • each driver signal D1-D7 comprises a component for the center sound beam CTB, the front left sound beam FLB, the front right sound beam FRB, the rear left sound beam RLB, and the rear right sound beam RRB.
  • the beam control data CD mentioned hereinbefore with respect to FIG. 2 comprises front left beam control data CD FL and front right beam control data CD FR.
  • the front left beam control data CD FL which is applied to the front left beam former FLBF, determines the particular characteristics of the front left sound beam FLB. These particular characteristics correspond with a particular relationship between the individual front left driver components S1 FL-S7 FL in terms of signal characteristics.
  • the front left beam former FLBF enforces this particular relationship, as it were, by providing an array of transfer characteristics. Each transfer characteristic produces a particular front left driver component in response to the front left channel signal FLC.
  • the front right beam control data CD FR which is applied to the front right beam former FRBF, determines the particular characteristics of the front right sound beam FRB in a similar fashion.
  • FIG. 4 illustrates an implementation of the front left beam former FLBF.
  • This implementation comprises a gain control stage G, an array of delay stages D1-D7, an array of weighting stages Wl -W7, and a front left beam control module CTFL.
  • the implementation illustrated in FIG. 4 will be referred to hereinafter as a delay-and-sum beam former.
  • the front right beam former FRBF may also take the form of the delay-and- sum beam former illustrated in FIG. 4. The same applies to the center beam former, the left rear beam former, and the right rear beam former.
  • the front left beam control module CTFL may be in the form of a software program that is running on a processor, which may be the same processor that implements the master control module CTM.
  • the gain control stage G allows an amplitude adjustment of the front left channel signal FLC.
  • the gain control stage G provides a scaled version of the front left channel signal FLC, which is applied to each delay stage D1-D7.
  • Each delay stage introduces a particular delay ⁇ T1- ⁇ T7. That is, each delay stage D1-D7 imposes a particular delay on the front left driver component concerned S1 FL-S7 FL with respect to a common reference in the form of the front left channel signal FLC.
  • Each weighting stage Wl -W7 multiplies a delayed version of the front left channel signal FLC with a particular weighting coefficient ⁇ 1 - ⁇ 7.
  • each weighting stage W1-W7 defines a particular magnitude relationship between the front left driver component concerned S1 FL-S7 FL and the front left channel signal FLC, which is the common reference. Accordingly, the array of delay stages D1-D7 and the array of weighting stages Wl -W7 impose a particular magnitude and delay relationship between the respective front left driver components. The particular characteristics of the front left sound beam FLB depend on this particular magnitude and delay relationship.
  • the front left beam control module CTFL controls the respective delays ⁇ T1- ⁇ T7 that the array of delay stages D1-D7 introduces on the basis of the front left beam control data CD FL.
  • the front left beam control module CTFL further controls the respective weighting coefficients ⁇ 1 - ⁇ 7 in the array of weighting stages W1-W7 on the basis of the front left beam control data CD FL. For example, let it be assumed that the front left beam control data CD FL specifies a particular direction and a particular width that the front left sound beam FLB should have.
  • the front left beam control module CTFL translates, as it were, these desired characteristics of the front left sound beam FLB into an array of delays ⁇ T1- ⁇ T7 and an array of weighting coefficients ⁇ 1 - ⁇ 7.
  • the array of delay stages D1-D7 and the array of weighting stages W1-W7 apply these delays and these weighting coefficients, respectively.
  • the front left beam former FLBF and the other beam formers may be implemented in various different manners.
  • the array of delay stages D1-D7 and the array of weighting stages Wl -W7 which are illustrated in FIG. 4, may be replaced by an array of filters.
  • an array of filters may be added to the array of delay stages Dl- D7 and the array of weighting stages Wl -W7.
  • Each filter has a particular impulse response.
  • Such filter-based implementations are characterized by an array of impulse responses.
  • the respective impulse responses can be calculated on the basis of a desired sound radiation pattern, which specifies a sound energy level as a function of angle.
  • the aforementioned array of impulse responses may be calculated by means of a numerical optimization method.
  • the desired sound radiation pattern and an actual sound radiation pattern are each expressed in the form of a series of sound energy levels at various frequencies for specific angles. Each angle represents a particular direction of sound radiation.
  • a matrix is established that specifies a sound propagation from each individual loudspeaker for each specific angle. Let it be assumed that there are M specific angles and N individual loudspeakers, M and N being integers. In that case, the matrix has M x N elements.
  • the actual sound radiation pattern can be expressed as a multiplication of the aforementioned matrix with the array of impulse responses, which a beam former provides. Since there are N individual loudspeakers, the array of impulse responses will comprises N elements.
  • the array of impulse responses should be chosen so that the actual sound radiation pattern best approximates the desired sound radiation pattern. This is a numerical minimization problem for which many mathematical solutions exists in the form of, for example, least-squares algorithms.
  • beam former implementations based on filters as described hereinbefore allow a better approximation of the desired sound radiation pattern than the delay-and-sum beam former illustrated in FIG. 4.
  • the delay-and- sum beam former produces a so-called main lobe that has an increasing width with decreasing frequency.
  • this beam former produces artifacts in the form of so- called side-and grating lobes, which are related to the fact that the loudspeaker or array has a finite length and a finite number of speakers. As a result of these artifacts, the respective sound beams illustrated in FIG. 1 may interfere with one another.
  • FIG. 5 illustrates a series of steps Sl -S3 that are carried out in the audiovisual system AVS in order to control the stereo width. This series of steps are carried out when, for example, the listener LI depresses a stereo width control button on the remote-control device RCD.
  • the remote-control device RCD may be provided with some form of display. In that case, the listener LI may navigate through a control menu and depress appropriate buttons in order to control the stereo width.
  • step S 1 the remote-control device RCD sends a stereo width command SWC to the master control module CTM of the audiovisual system AVS by means of, for example, an infrared signal, a radio signal, or an ultrasound signal (RCD : SWC ⁇ CTM).
  • the stereo width command SWC may comprise a value that expresses a desired stereo width, or a degree of increase or decrease of the stereo width.
  • the stereo width command SWC may also be a unitary code word expresses an increment of the stereo width, or a unitary code word that expresses a decrement of the stereo width, whichever applies.
  • the listener LI controls the stereo width by depressing one or more times a stereo width increment control button, or a stereo width decrement control button, or both, until he or she considers that the stereo width is satisfactory. That is, such a stereo width control is similar to a volume control by depressing one or more times a "volume +" button or a "volume -" button.
  • the master control module CTM In step S2, the master control module CTM generates front left beam control data CD FL and front right beam control data CD FR on the basis of the stereo width command (CTM[SWC] : CD FL ⁇ CTFL, CD FR ⁇ CTFR).
  • the front left beam control data CT FL and the front right beam control data CT FR may specify a desired beam width for the front left sound beam FLB and the front right sound beam FRB, respectively. That is, the master control module CTM may translate, as it were, the stereo width command SWC into a desired front left beam width and a desired front right beam width. In case a reduction of the stereo width is desired, the width of the front left sound beam FLB and that of the front right sound beam FRB is increased.
  • the width of the front left sound beam FLB and that of the front right sound beam FRB is decreased.
  • the front left beam control data CT FL and the front right beam control data CD FR may directly specify a beam width change for the front left sound beam FLB and the front right sound beam FRB, respectively.
  • the master control module CTM can translate the stereo width command SWC into a desired front left beam width and a desired front right beam width, or into a front left beam width change and a front right beam width change.
  • This stereo-to-beam width translation can be relatively simple if, for example, the stereo width command SWC is a unitary code word.
  • the desired front left beam width and the desired front right beam width correspond with an increase or a decrease of these respective beam widths by a given amount.
  • the stereo-to-beam width translation can be more sophisticated if, for example, the stereo width command SWC expresses a desired stereo width.
  • the stereo-to-beam width translation may take into account, for example, one or more parameters that relate to the location of the audiovisual system AVS and the location of the listener LI in the room RO illustrated in FIG. 1.
  • the distance between the audiovisual system AVS and the left wall WL, as well as the distance between the audiovisual system AVS and the right wall WR may constitute such parameters.
  • the distance between the listener LI and the audiovisual system AVS may also constitute such a parameter.
  • a processor may execute a manual set up program that invites a user to specify the aforementioned distances. The user may specify these distances by, for example, typing corresponding numerical keys on the remote-control device RCD.
  • the processor may execute an automatic setup program, which controls a number of transducers capable of measuring the aforementioned distances.
  • the remote-control device RCD may comprise such a transducer for measuring the distance between the listener LI and the audiovisual system AVS. This transducer can also be used for measuring the other distances, if the listener LI moves to the left wall WL and to the right wall WR while holding the remote-control device RCD.
  • the front left beam control module CTFL controls the array of delay stages D1-D7 and the array of weighting stages W1-W7, which are illustrated in FIG. 4, on the basis of the front left beam control data CD FL (CTFL[CD FL] : [ ⁇ T1, .., ⁇ T7; ⁇ l, .., ⁇ 7] @FLBF).
  • the front left beam control module CTFL translates, as it were, the desired front left beam width, which the front left beam control data CD FL specifies, into respective delays and respective weighting coefficient for the aforementioned arrays.
  • the respective delays and the respective weighting coefficients that the front left beam control module CTFL establishes causes the front left sound beam FLB to substantially have the desired width.
  • a front right beam control module controls the array of delay stages and the array of weighting stages comprised in the front right beam former FRBF on the basis of the front right beam control data CD FR (CTFR[CD FR] : [ ⁇ T1, .., ⁇ T7; ⁇ l, .., ⁇ 7]@FLBR).
  • CD FR front right beam control data
  • the front right sound beam FRB will have a beam width that substantially corresponds with the desired beam width.
  • FIGS. 6 and 7 illustrate a stereo width control in accordance with the invention.
  • the stereo width control occurs in the room RO illustrated in FIG. 1, where the listener LI is sitting in front of the audiovisual system AVS.
  • the stereo width control is accomplished by controlling the width of the front left sound beam FLB as described hereinbefore. It is assumed that the width of the front right sound beam FRB is controlled in a similar fashion. For the sake of simplicity, FIGS. 6 and 7 do not show the front right sound beam FRB and the other sound beams.
  • the front left sound beam FLB which is directed towards the left wall WL, is relatively narrow. Since the front left sound beam FLB is relatively narrow, the front left sound beam FLB exclusively reaches the listener LI by reflection against the left wall WL.
  • the distance between the listener LI and the audiovisual system AVS is smaller than the distance between the audiovisual system AVS and the left wall WL.
  • the phantom left loudspeaker PL that the listener LI perceives has a location that is relatively distant from the listener LI.
  • the phantom right loudspeaker PR which is not illustrated in FIG. 6, also has a location that is relatively distant from the listener LI for similar reasons.
  • the stereo field that the listener LI perceives will be relatively wide, which the listener LI may perceive as unnatural.
  • the front left sound beam FLB is relatively wide as a result of the stereo field control as illustrated in FIG. 5. Since the front left sound beam FLB is relatively wide, a portion of the front left sound beam FLB reaches the listener LI directly, whereas another portion reaches the listener LI by reflection against the left wall WL. The listener LI will thus receive a mixture of these respective portions. The portion that reaches the listener LI directly causes the phantom left loudspeaker PL to have a location that is closer to the listener LI than the location illustrated in FIG. 6.
  • the stereo field in FIG. 7 is less wide than that in FIG. 6.
  • FIGS. 8, 9, and 10 illustrate a beam width control, which is based on shifting a focal point.
  • the beam width control illustrated in these figures can be achieved with the delay-and-sum beam former illustrated in FIG. 4. More specifically, the array of delay stages D1-D7 can be made to introduce respective delays that define a focal point FP.
  • the focal point FP is a unique point where the signals of all loudspeakers in the loudspeaker array LSA arrive simultaneously when an impulse is applied to the front left beam former FLBF.
  • the loudspeaker array LSA is represented in each of the FIGS. 8, 9, and 10.
  • the focal point FP is behind the loudspeaker array LSA and relatively close to the loudspeaker array LSA.
  • the loudspeaker array LSA produces a sound beam that has a relatively large degree of divergence.
  • the sound beam is therefore relatively wide.
  • the focal point FP illustrated in FIG. 8 can be achieved by means of respective delays that are relatively widely spaced. That is, there is a relatively large time shift between two driver signals that are applied two neighboring loudspeakers in the array.
  • the focal point FP is behind the loudspeaker array LSA and relatively distant from the loudspeaker array LSA.
  • the loudspeaker array LSA produces a sound beam that has a relatively small degree of divergence.
  • the sound beam is therefore relatively narrow.
  • the focal point FP illustrated in FIG. 9 can be achieved by means of respective delays that are relatively narrowly spaced. That is, there is a relatively small time shift between two driver signals that are applied two neighboring loudspeakers in the array.
  • the focal point FP is in front of the loudspeaker array LSA.
  • the loudspeaker array LSA produces a sound beam that is converging towards the focal point FP and that is diverging from the focal point FP onwards.
  • a focal point in front of the loudspeaker array LSA may be useful to prevent that a relatively large portion of the front left sound beam FLB or the front right sound beam FRB reaches the listener LI directly.
  • a relatively large portion of the front left sound beam FLB or the front right sound beam FRB may reach the listener LI directly if, for example, the loudspeaker array LSA is relatively narrow.
  • a relatively large portion of these sound beams may also reach the listener LI directly if the listener LI is relatively close to the audiovisual system AVS.
  • an increase of perceived stereo width may be desired.
  • Such an increase of perceived stereo width may be achieved by a focal point in front of the loudspeaker array LSA.
  • the invention may be applied to advantage in any type of product or method related to stereo sound rendering.
  • the audiovisual system AVS illustrated in FIG. 1 is merely an example.
  • the invention may equally be applied to advantage in, for example, an audio system or a personal computer that is provided with an array of loudspeakers.
  • FIGS. 3 and 4 illustrate an implementation example among many other possible ones.
  • amplifiers are placed behind combiners.
  • amplifiers may be placed in front of combiners.
  • the weighting stages may be omitted for reasons of simplicity.
  • FIG. 5 illustrates an implementation example in which the stereo width command is effectively translated into respective beam width commands, which are applied to individual beam formers.
  • the stereo width command may directly be applied to individual beam formers, which directly translate the stereo width command into parameter settings for respective stages within the individual beam formers.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Stereophonic System (AREA)

Abstract

La présente invention concerne un système de rendu sonore stéréo (AVS), dans lequel un amplificateur de mise en forme de faisceaux entraîne la production par un réseau de haut-parleurs d'une paire de faisceaux sonores, dont chacun présente une largeur particulière. Un faisceau sonore est dirigé vers la gauche, tandis que l'autre faisceau sonore est dirigé vers la droite. Un contrôleur entraîne l'ajustement de la largeur d'au moins un desdits faisceaux sonore par l'amplificateur de mise en forme de faisceaux (FLB) en réponse à une commande de largeur stéréo.
PCT/IB2008/051606 2007-05-03 2008-04-25 Système de rendu sonore stéréo WO2008135887A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP07107425 2007-05-03
EP07107425.6 2007-05-03

Publications (1)

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WO2008135887A1 true WO2008135887A1 (fr) 2008-11-13

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WO (1) WO2008135887A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2434783A1 (fr) * 2010-09-24 2012-03-28 Panasonic Automotive Systems Europe GmbH Adaptation stéréo automatique
FR3006802A1 (fr) * 2013-06-07 2014-12-12 Thales Sa Procede et systeme de diffusion directive de signaux sonores
CN109155886A (zh) * 2016-05-25 2019-01-04 哈曼国际工业有限公司 非对称无源组延迟波束形成

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004179711A (ja) * 2002-11-25 2004-06-24 Sony Corp スピーカ装置および音響再生方法
US20040208324A1 (en) * 2003-04-15 2004-10-21 Cheung Kwok Wai Method and apparatus for localized delivery of audio sound for enhanced privacy
WO2006004159A1 (fr) * 2004-07-07 2006-01-12 Yamaha Corporation Procede de commande de directivite d'un haut-parleur et dispositif de reproduction audio
EP1705955A1 (fr) * 2004-01-05 2006-09-27 Yamaha Corporation Appareil d'acheminement de signaux audio pour reseau de haut-parleurs

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004179711A (ja) * 2002-11-25 2004-06-24 Sony Corp スピーカ装置および音響再生方法
US20040208324A1 (en) * 2003-04-15 2004-10-21 Cheung Kwok Wai Method and apparatus for localized delivery of audio sound for enhanced privacy
EP1705955A1 (fr) * 2004-01-05 2006-09-27 Yamaha Corporation Appareil d'acheminement de signaux audio pour reseau de haut-parleurs
WO2006004159A1 (fr) * 2004-07-07 2006-01-12 Yamaha Corporation Procede de commande de directivite d'un haut-parleur et dispositif de reproduction audio

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2434783A1 (fr) * 2010-09-24 2012-03-28 Panasonic Automotive Systems Europe GmbH Adaptation stéréo automatique
FR3006802A1 (fr) * 2013-06-07 2014-12-12 Thales Sa Procede et systeme de diffusion directive de signaux sonores
CN109155886A (zh) * 2016-05-25 2019-01-04 哈曼国际工业有限公司 非对称无源组延迟波束形成
EP3466112A4 (fr) * 2016-05-25 2019-12-18 Harman International Industries, Inc. Formation de faisceau de retard de groupe passif asymétrique

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