EP1372356A1 - Method for reproducing a plurality of mutually unrelated sound signals, especially in a motor vehicle - Google Patents

Abstract

In a method for reproducing a plurality of mutually unrelatedsound signals (26, 28) by means of a plurality of loudspeakers(12, 14), first, the sound signals (26, 28) are receivedfrom one or more sound sources. Next, the received sound signals(26, 28) are filtered in a crosstalk cancellation filter(16) in order to cancel out crosstalk between the individualsound signals (26, 28). Finally, the filtered sound signalsare supplied to the loudspeakers (12, 14). In an embodimentof the method according to the invention, the sound signals(26, 28) comprise multichannel sound signals and the multichannelsound signals are filtered in the crosstalk cancellationfilter (16) in order to cancel out cross talk betweenthe individual channels of the multichannel sound signals.The filtered multichannel sound signals are supplied to theloudspeakers (12, 14).

Description

• The invention relates to a method for reproducing a pluralityof mutually unrelated sound signals by means of a pluralityof loudspeakers and to a sound reproducing system forapplying this method.
• When two or more people want to listen to different audiosignals inside the same space, for example in case of a dualwindow television or inside a car, at least one of them typicallyneeds to wear headphones. However, JP08289389 disclosesa acoustic system for use in a vehicle in which each seat isprovided with one or more loudspeakers. Each person in thecar can select a sound signal from a plurality of soundsources independent from the selection made by the other persons.By means of a signal matrix switch the selected soundsignal is supplied to the loudspeaker(s) closest to the personmaking the selection. In such a situation it may easilyoccur that a person in one seat is bothered by the sound signalreproduced by the loudspeakers associated with anotherseat.
• In order to reduce this effect the on-vehicle acoustic deviceof JP09171387 provides a masking means which outputs noisefrom a speaker to mask the sound signals reproduced by theloudspeakers of other seats.
• In a situation where different people have selected differentsound signals it might easily occur that these differentsound signals interfere with each other so that the perceivedsound quality of the sound signals is relatively low. Therefore,in order to cancel the contribution of the unwanted sound signals, in accordance with the invention, there isprovided a method for reproducing a plurality of mutually unrelatedsound signals by means of a plurality of loudspeakers,the method comprising:
• receiving the sound signals from one or more sound sources;
• filtering the received sound signals in a crosstalk cancellationfilter in order to cancel out crosstalk between theindividual sound signals;
• supplying the filtered sound signals to the loudspeakers.
• So, shortly said, according to the invention, unwantedcrosstalk between the individual sound signals is eliminatedby means of a crosstalk cancellation filter.
• Crosstalk cancellation filters are known per se, for examplefrom M.I.T. Media Laboratory Perceptual Computing SectionTechnical Report No. 342, July 6, 1995, Transaural 3-D audio,by William G. Gardner. In this report a 3-D audio system isdisclosed in which a stereo sound signal is first processedby a binaural spatializer. The output of the spatializer isthereafter fed to a transaural audio system which deliversbinaural signals to the ears of a person using a pair of stereoloudspeakers. The transaural audio system includes acrosstalk cancelation filter for canceling the crosstalkleakage from each loudspeaker to the opposite ear. This reportdoes not address the problem of crosstalk between mutuallyunrelated sound signals which are reproduced for differentpeople.
• In an embodiment of the method according to the invention thesound signals comprise multichannel sound signals and themethod comprises the additional step of filtering the multichannelsound signals in the crosstalk cancellation filterin order to cancel out cross talk between the individualchannels of the multichannel sound signals, the filtered multichannel sound signals being supplied to the loudspeakers.The operation of the crosstalk cancellation filter is in thisrespect similar to the operation of the crosstalk cancelationfilter as used in the 3-D audio system of Gardner. Thecrosstalk leakage from each channel to the other channel(s)is thereby effectively eliminated.
• In a preferred embodiment of the method according to the inventionthe multichannel sound signals are stereo sound signalsfor reproduction by a pair of stereo loudspeakers.
• In another embodiment of the method according to the inventionthe method comprises the further steps of processing thestereo sound signals in a binaural spatializer and of filteringthe binaurally spatialized stereo sound signals in thecrosstalk cancellation filter.
• In a further embodiment of the method according to the inventionthe loudspeakers are provided on or above a plurality ofseats or chairs.
• In another embodiment of the method according to the inventionthe loudspeakers are provided on the top of the backs ofthe seats or chairs.
• In yet another embodiment of the method according to the inventionthe loudspeakers are provided on headrests of theseats or chairs. Alternatively, the loudspeakers may be providedabove the seats or chairs, e.g. on the ceiling abovethe seats or chairs.
• In a preferred embodiment of the method according to the inventionthe seats or chairs are comprised in a car or in aspace for presenting multi-media shows such as motion pictures.
• The invention also relates to a sound reproducing system, forapplying the method of anyone of the preceding claims, comprisingsound processing means and coupled thereto loudspeakers,the sound processing means being arranged for receivinga plurality of sound signals from one or more sound sources,the sound processing means comprising a crosstalk cancellationfilter for filtering the received sound signals in orderto cancel out crosstalk between the individual sound signals,the sound processing means being further arranged for supplyingthe filtered sound signals to the loudspeakers.
• Preferably, the sound signals comprise multichannel soundsignals and the crosstalk cancellation filter is arranged forfiltering the multichannel sound signals in order to cancelout cross talk between the individual channels of the multichannelsound signals, the sound processing means beingfurther arranged for supplying the filtered multichannelsound signals to the loudspeakers. The multichannel soundsignals may be stereo sound signals for reproduction by apair of stereo loudspeakers.
• The sound processing means may comprise a binaural spatializerfor processing the stereo sound signals and for supplyingthe binaurally spatialized sound signals to the crosstalkcancellation filter.
• Preferably, the loudspeakers are provided on or above a pluralityof seats or chairs, e.g. on the top of the backs ofthe seats or chairs or on headrests of the seats or chairs.Alternatively, the loudspeakers may be provided above theseats or chairs, e.g. on the ceiling above the seats orchairs. The seats or chairs may be comprised in a car or in aspace for presenting multi-media shows such as motion pictures.
• The invention will be apparent from and elucidated with referenceto the example as described in the following and tothe accompanying drawing, which shows in the sole Figureschematically the sound reproducing system according to theinvention.
• The sole Figure shows schematically an embodiment of a soundreproducing system according to the invention. The sound reproducingsystem comprises sound processing means 10 and coupledtheretoloudspeakers 12, 14. The sound processing means10 are arranged for receiving a plurality ofsound signals26, 28 from one or more sound sources (not shown). In thisexample, thesound signals 26, 28 are stereo sound signalsand theloudspeakers 12, 14 are stereo loudspeakers for reproducingthe stereo sound signals. However, the sound reproducingsystem may equally well be used with other multichannelor single channel sound signals with corresponding loudspeakerarrangements.
• The sound processing means 10 comprises twobinaural spatializers18, 20 and acrosstalk cancellation filter 16. Thebinauralspatializers 18, 20 are arranged for processing thestereo sound signals 26, 28 and for supplying the resultingbinaurallyspatialized sound signals 30, 32 to thecrosstalkcancellation filter 16. Thecrosstalk cancellation filter 16is arranged for filtering the binaurallyspatialized soundsignals 30, 32 in order to cancel out crosstalk between theindividual sound signals 30, 32 and between the individualchannels of the multichannel sound signals. In the Figurethis filtering is shown in detail for the left channel of thestereo sound signal 26 and the therewith corresponding leftchannel of the binaurally spatializedstereo sound signal 30.The crosstalk between this channel and each of the four channelsof thestereo sound signals 30 and 32 is canceled by means of a specific crosstalk cancellation unit: for instancethe crosstalk between the left channel of sound signal 30(AL) and the right channel of sound signal 32 (BR) is cancelledby means of a specific crosstalk cancellation unit BR-AL.The output signals of the four specific crosstalk cancellationunits are combined in an adder 22 and the combinedsignal, from which the crosstalk is substantially removed, isfinally supplied to the speaker 12 (Speaker AL). Thecrosstalk cancellation for the other channels AR, BL and BRis not shown in detail in the Figure but is similar in operationto the crosstalk cancellation for the AL channel. Foreach of these other channels AR, BL and BR four specificcrosstalk cancellation units and an adder 22 are provided.The filtered stereo sound signals are supplied to theloudspeakers12 and 14. In this example, theloudspeakers 12 arethe left loudspeakers reproducing the left channel of thestereo sound signals and theloudspeakers 14 are the rightloudspeakers reproducing the right channel of the stereosound signals.
• Crosstalk cancellation filters and binaural spatializers areknown per se, for example from M.I.T. Media Laboratory PerceptualComputing Section Technical Report No. 342, July 6,1995, Transaural 3-D audio, by William G. Gardner.
• In one alternative embodiment (not shown), the sound processingmeans 10 does not comprise thebinaural spatializers 18and 20 in which case thesound signals 26, 28 are directlysupplied to thecrosstalk cancellation filter 16.
• Theloudspeakers 12, 14 may be provided on or above a pluralityof seats or chairs (not shown). For example, theloudspeakers12, 14 may be provided on the top of the backs ofthe seats or chairs or on headrests of the seats or chairs.Alternatively, theloudspeakers 12, 14 may be mounted on a ceiling above the seats or chairs. The seats or chairs arepreferably comprised in a car, in which situation applicationof the invention allows the passengers of the car to listento different sound signals without having to wear headphonesand without substantial interference of the different soundsignals. The seats or chairs may also be comprised in a spacefor presenting multi-media shows, such as a cinema in whichmotion pictures are shown, in which situation application ofthe invention may allow members of the audience to listen todifferent language versions of the sound signals without havingto wear headphones and without substantial interferenceof the different sound signals.
• Now, the invention has been disclosed with reference to theFigures in connection with the disclosure of preferred embodiments.However, persons skilled in the art will readily recognizevarious amendments, modifications, and combinations.Therefore, the above disclosure should not be considered aslimitative, but rather illustrative, and the due scope of thepresent invention should be determined from the scope of theClaims appended hereto, the invention being embodied in eachnew characteristic and each combination of characteristics.Any reference signs do not limit the scope of the claims. Theword "comprising" does not exclude the presence of other elementsor steps than those listed in a claim. Use of the word"a" or "an" preceding an element does not exclude the presenceof a plurality of such elements.

Claims (16)

1. Method for reproducing a plurality of mutually unrelatedsound signals by means of a plurality of loudspeakers,characterized by:

   receiving the sound signals from one or more soundsources;

   filtering the received sound signals in a crosstalkcancellation filter in order to cancel outcrosstalk between the individual sound signals;

   supplying the filtered sound signals to the loudspeakers.
2. Method for reproducing a plurality of mutually unrelatedsound signals, according to claim 1,characterizedin that the sound signals comprise multichannelsound signals and wherein the method comprises the additionalstep of filtering the multichannel sound signalsin the crosstalk cancellation filter in order tocancel out cross talk between the individual channelsof the multichannel sound signals.
3. Method for reproducing a plurality of mutually unrelatedsound signals, according to claim 2,characterizedin that the multichannel sound signals are stereosound signals for reproduction by a pair of stereoloudspeakers.
4. Method for reproducing a plurality of mutually unrelatedsound signals, according to claim 3,characterizedin that the method comprises the further steps ofprocessing the stereo sound signals in a binaural spatializerand of filtering the binaurally spatializedstereo sound signals in the crosstalk cancellation filter.
5. Method for reproducing a plurality of mutually unrelatedsound signals, according to anyone of the precedingclaims,characterized in that the loudspeakers areprovided on or above a plurality of seats or chairs.
6. Method for reproducing a plurality of mutually unrelatedsound signals, according to claim 5,characterizedin that the loudspeakers are provided on the topof the backs of the seats or chairs.
7. Method for reproducing a plurality of mutually unrelatedsound signals, according to claim 5,characterizedin that the loudspeakers are provided on headrestsof the seats or chairs.
8. Method for reproducing a plurality of mutually unrelatedsound signals, according to anyone of the claims5-7,characterized in that the seats or chairs are comprisedin a car.
9. Sound reproducing system, for applying the method ofanyone of the preceding claims, comprising sound processingmeans and coupled thereto loudspeakers,characterizedby the sound processing means being arrangedfor receiving a plurality of sound signals from one ormore sound sources, the sound processing means comprisinga crosstalk cancellation filter for filtering thereceived sound signals in order to cancel out crosstalkbetween the individual sound signals, the sound processingmeans being further arranged for supplying thefiltered sound signals to the loudspeakers.
10. Sound reproducing system according to claim 9,characterizedin that the sound signals comprise multichannel sound signals and wherein the crosstalk cancellationfilter is arranged for filtering the multichannel soundsignals in order to cancel out cross talk between theindividual channels of the multichannel sound signals.
11. Sound reproducing system according to claim 10,characterizedin that the multichannel sound signals are stereosound signals for reproduction by a pair of stereoloudspeakers.
12. Sound reproducing system according to claim 11,characterizedin that the sound processing means comprises abinaural spatializer for processing the stereo soundsignals and for supplying the binaurally spatializedsound signals to the crosstalk cancellation filter.
13. Sound reproducing system, according to anyone of theclaims 9-12,characterized in that the loudspeakers areprovided on or above a plurality of seats or chairs.
14. Sound reproducing system, according to claim 13,characterizedin that the loudspeakers are provided on thetop of the backs of the seats or chairs.
15. Sound reproducing system, according to claim 13,characterizedin that the loudspeakers are provided onheadrests of the seats or chairs.
16. Sound reproducing system, according to anyone of claims13-15,characterized in that the seats or chairs arecomprised in a car.

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