LOUDSPEAKER SYSTEM

Abstract

A loudspeaker system for a vehicle includes a loudspeaker array including a plurality of electroacoustic sound transducers that can be controlled individually, such that a user-specific audio signal can be reproduced for different users at different listening positions in a vehicle interior of the vehicle via the plurality of electroacoustic sound transducers. Here, the loudspeaker array or a sound outlet of the loudspeaker array is arranged in particular between at least two of the listening positions in the vehicle interior, i.e. for example between the driver and the passenger seat.

Claims

1. Loudspeaker system for a vehicle, comprising: a loudspeaker array comprising a plurality of electroacoustic sound transducers that can be controlled individually, such that a user-specific audio signal can be reproduced for different users at different listening positions in a vehicle interior via the plurality of electroacoustic sound transducers, wherein the loudspeaker array is arranged in a roof lining of the vehicle, centrally between at least all listening positions in the vehicle interior, such that a distance between the loudspeaker array and all of the listening positions is the same, with a deviation of +/30%, wherein the loudspeaker system comprises, per listening position, at least one additional loudspeaker system comprising at least one additional loudspeaker or an additional loudspeaker array, wherein the additional loudspeaker system comprises a structure-borne sound loudspeaker that is arranged in a foot space allocated to the listening position, in a seat allocated to the listening position and/or a headrest allocated to the listening position and/or that is mechanically coupled to the seat allocated to the listening position; wherein the loudspeaker system is configured to perform, with the help of the plurality of the electroacoustic sound transducers of the loudspeaker array, acoustic beamforming for forming the beams; wherein middle and higher frequencies are reproduced in a directed manner for the different listening positions by means of the array, while the low frequencies are only represented locally via the structure-bound sound transducer.

2. Loudspeaker system according to claim 1, wherein the additional loudspeaker system is closer to the user than the loudspeaker array.

3. Loudspeaker system according to claim 1, wherein the additional loudspeaker system is arranged in a seat allocated to the listening position, a position of the A column, B column, C column allocated to the listening position and/or the roof lining and/or a headrest allocated to the listening position.

4. Loudspeaker system according to claim 1, wherein the additional loudspeaker system is configured to output sound such that, with regard to the further listening positions, a large part of the sound reaches the respective listening position.

5. Loudspeaker system according to claim 1, wherein the additional loudspeaker system is arranged closer to one ear of the user than to the other ear of the user.

6. Loudspeaker array according to claim 5, wherein the loudspeaker array comprises a further plurality of third electroacoustic sound transducers.

7. Loudspeaker system according to claim 1, wherein the loudspeaker system is configured, with the help of the additional loudspeaker system, to reproduce stereo per listening position or mono with local level increase.

8. Loudspeaker system according to claim 1, wherein the loudspeaker system is configured to generate, with the help of the plurality of the electroacoustic sound transducers, at least two beams or one stereo beam per listening position; and/or wherein the loudspeaker system is configured to virtually position sound sources in space by using transfer functions emulating psychoacoustic effects.

9. Loudspeaker system according to claim 1, wherein beamforming is based on direct and/or indirect sound reproduction with regard to the user.

10. Loudspeaker system according to claim 1, wherein a sound pressure level and/or radiation direction per beam allocated to a listening position are selected such that the sound pressure level is below a listening threshold at other listening positions after absorption and/or reflection.

11. Loudspeaker system according to claim 1, wherein the loudspeaker system is configured to perform beamforming by considering a seat adjustment or a head position of the user at the listening position and/or to track the beams in dependence on the seat adjustment and/or the head position of the user.

12. Loudspeaker system according to claim 1, wherein the loudspeaker system comprises a control that is configured to individually control the electroacoustic sound transducers.

13. Loudspeaker system according to claim 1, wherein the loudspeaker system comprises a loudspeaker array, comprising: a plurality of first electroacoustic sound transducers arranged on a first line; and a plurality of second electroacoustic sound transducers arranged on a first line or a line parallel to the first line, wherein an average distance between the first electroacoustic sound transducers is smaller than an average distance between the second electroacoustic sound transducers; or a loudspeaker array, comprising: a plurality of first electroacoustic sound transducers arranged in a first planar area; and a plurality of second electroacoustic sound transducers arranged in the first planar area, wherein an average density of the first electroacoustic sound transducers is smaller than an average density of the second electroacoustic sound transducers.

14. Loudspeaker system according to claim 13, wherein the plurality of first electroacoustic sound transducers is surrounded all around by the plurality of second electroacoustic sound transducers.

15. Loudspeaker array according to claim 13, wherein at least two of the first electroacoustic sound transducers are encompassed by two of the second electroacoustic sound transducers.

16. Loudspeaker array according to claim 13, wherein the first electroacoustic sound transducers are configured to reproduce a first frequency range defined by a first center frequency and the second electroacoustic sound transducers are configured to reproduce a second frequency range defined by a second center frequency, wherein the first center frequency is higher than the second center frequency.

17. Loudspeaker system for a vehicle, comprising: a loudspeaker array comprising a plurality of electroacoustic sound transducers that can be controlled individually, such that a user-specific audio signal can be reproduced for different users at different listening positions in a vehicle interior via the plurality of electroacoustic sound transducers, wherein the loudspeaker array or a sound outlet of the loudspeaker array is arranged between at least two of the listening positions in the vehicle interior, wherein the loudspeaker system comprises, per listening position, at least one additional loudspeaker system comprising at least one additional loudspeaker or an additional loudspeaker array, wherein the additional loudspeaker system comprises a structure-borne sound loudspeaker that is arranged in a foot space allocated to the listening position, in a seat allocated to the listening position and/or a headrest allocated to the listening position and/or that is mechanically coupled to the seat allocated to the listening position, wherein the loudspeaker system comprises a loudspeaker array, comprising: a plurality of electroacoustic sound transducers coupled to first sound guides for sound output in a first area, wherein each sound guide comprises a sound outlet opening, wherein the plurality of sound outlet openings are arranged such that an average distance between the sound outlet openings is smaller than a possible average distance between the juxtaposed electroacoustic sound transducers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:

[0026] FIG. 1a is an exemplary diagram of an arrangement of a loudspeaker array in a vehicle according to a first embodiment (mono) of the first aspect;

[0027] FIG. 1b is a schematic diagram of an arrangement in a vehicle according to a further embodiment (partly stereo) of the first aspect;

[0028] FIG. 1c, d are schematic diagrams of the arrangement of a loudspeaker array in combination with additional sound transducers in a vehicle according to further embodiments (partly stereo) of the first aspect;

[0029] FIG. 2a is a schematic diagram of a loudspeaker array with sound transducers of different types for the loudspeaker system according to the embodiments of FIGS. 1a-1d;

[0030] FIG. 2b is a schematic diagram of a linear loudspeaker array with sound transducers of different types according to the embodiment of the second aspect;

[0031] FIG. 2c is a schematic diagram of a loudspeaker array with planar-arranged sound transducers of different types according to a further embodiment of the second aspect;

[0032] FIG. 2d is a diagram of a loudspeaker array with sound transducers of different types according to an additional embodiment of the second aspect; and

[0033] FIG. 3 is a schematic diagram of a loudspeaker array with a plurality of sound guides according to an embodiment of the third aspect.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Before embodiments of the present invention will be discussed in more detail based on the figures, it should be noted that the same elements or structures are provided with the same reference numbers, such that the description is inter-exchangeable or inter-applicable.

[0035] FIG. 1a shows a schematically illustrated vehicle interior 10 in a top view with four listening positions 12a, 12b, 12c and 12d, each defined by a seat on which the potential listener can sit. The loudspeaker system 1 for the vehicle interior 10 includes a loudspeaker array 20 including the plurality of electroacoustic sound transducers 20a-20h.

[0036] As illustrated herein, the array 20 with regard to the vehicle interior 10 is arranged in a relatively central manner, which has the effect that the array 20 is arranged at least between two listening positions (subset of all listening positions 12a-12d), here even between the four listening positions 12a-12d. Possible installation spaces for the loudspeaker array are, for example the roof lining, the central console, but also alternatively the dashboard and the rear shelf, respectively. Generally, this means that the loudspeaker array 20 can be installed above or below or even at the same height as the listening zones 12a-12d and the ear height of the listener, respectively. For completeness sake, it should be noted that centrally relates to all listening zones 12a-12d or at least to a subset of the listening zones 12a-12d, e.g., the listening zone 12a and 12b. In the following, the mode of operation of the loudspeaker system for the vehicle realized in that manner will be discussed.

[0037] In the illustrated example, the loudspeaker system array forms, per listening position 12a-12d, one beam 22a-22d that is advantageously directed to the listening zones 12a-12d or at least allocated to the same. The formation of these beams 22a-22d is performed in that the sound transducers 20a-20h of the loudspeaker array 20 are differently controlled, for example by considering so-called beamforming algorithms which can also incorporate the radiation characteristic of the individual transducers 20a-20h as well as influences of room acoustics. In the context of this signal processing, reference is made to the basics of the teachings of wave field synthesis which largely provides the basis for the beamforming performed herein. This means that the loudspeaker array 20 is configured to build a separate beam 22a-22d per listening position 12a-12d, wherein, due to the central arrangement, each beam 22a-22d is oriented oppositely with regard to its orientation (from the center towards the listening positions 12a-12d). Additionally (due to the central arrangement), the loudspeaker array 20 has approximately the same distance to each listening position 12a-12d, such that each beam 22a-22d has similar characteristics (e.g., expansion and level). These two characteristics contribute significantly to the obtained channel separation between the channels 22a-22d. An advantage of beams 22a-22d generated by beamforming is that the channel separation is so good that user-specific audio signals can be generated for the listening zones 12a-12c. Due to this, not only a different audio signal in the sense of loudness but even different audio content can be reproduced in the different listening zones 12a-12d. Additionally, it would also be possible that in one of the sound zones 12a-12d silence can specifically be generated by noise cancellation.

[0038] With reference to the embodiment of FIG. 1a, it should be noted that the illustrated arrangement even fulfils a second optional condition, namely that the distance between the loudspeaker array 20 and the individual listening positions 12a-12d is essentially the same, i.e., with a tolerance of +/30% (central arrangement). Further, the central position of the array 20 reduces spurious influences of room acoustics with regard to the sound zones, e.g., due to sound reflections at the side windows.

[0039] According to embodiments, instead of the entire loudspeaker array 20, a sound outlet of a sound guide (cf. FIG. 3) coupled to the loudspeaker array can be positioned centrally or generally between at least two of the listening zones 12a-12d. The sound guide typically includes one sound conductor per sound transducer 20a-20h coupled to the respective sound transducer 20a-20h, wherein a plurality of the sound outlets of the sound conductors form the sound outlet of the sound guide. Here, the actual sound transducer array 20 can be installed at a specific position within the car (e.g., in the trunk), e.g. due to lack of space, and the sound guide can guide the sound to the respective central sound outlet point.

[0040] By loudspeaker arrays arranged in that way, it is also possible to generate stereo or even 3D surround sound per listening position 12a-12d as is illustrated with reference to FIG. 1b.

[0041] FIG. 1b shows the top view of the vehicle interior 10 with the four listening positions 12a-12d and the loudspeaker array 20 of the loudspeaker system 1. Generating stereo is discussed based on the position 12a, however can also be transferred to the other listening positions 12a-12d.

[0042] As illustrated in FIG. 1b, a double beam including the beams 22aL and 22aR is generated for the listening position 12a. The beams 22aL and 22aR are, on the one hand, directed to the left ear (22aL) and, on the other hand, to the right ear (22aR) of the listener at the listening position 12a. Generating sound channels per listening position 12a-12d is not limited to the number 2 for stereo. Rather, several beams can be generated per listening position 12a-12d in order to simulate surround sound. Here, according to further embodiments, it would also be possible to consider transfer functions emulating psychoacoustic effects when generating the beams 22aL, 22aR, 22b, 22c and 22d in signal processing in order to improve positioning of the virtual sound sources in the interior 10. Examples for such transfer functions are HRTF functions and/or Blauert's directional bands.

[0043] According to further embodiments, it would also be possible that when orienting the beams 22aL, 22aR, 22b, 22c and 22d, sound reflections (e.g., via glass areas) or sound absorption are considered. It is also considered in advance to what extent direct sound reproduction and/or indirect sound reproduction, i.e. by incorporating wall reflections or also optional sound guides, is used.

[0044] Again, according to further embodiments, it would be possible that the beams 22aL, 22aR, 22b, 22c and 22d are oriented in dependence on the seating position defining the listening position 12a-12b, 12c and 12d. Here, for example, informational coupling of the loudspeaker system to the open (electric) seat adjustment would be possible.

[0045] A further embodiment for the loudspeaker system is disclosed in FIGS. 1c and 1d, where the central loudspeaker array 20 is combined with at least one additional loudspeaker or additional loudspeaker array (or generally with an additional system including at least one additional loudspeaker). Possible positions for the additional loudspeaker(s) are the A, B, C column, the headrest or the roof lining.

[0046] FIG. 1c shows the vehicle interior 10 (top view) with the four listening positions 12a-12d, the centrally arranged loudspeaker array 20 of the loudspeaker system 1, wherein an additional loudspeaker 30a (here, for example, in the roof lining, alternatively B column or headrest) is allocated to the first listening position 12a. From the point of view of the listener, at the listening position 12a, this additional loudspeaker 30a is on a side facing away from the loudspeaker array 20 (here on the left) and is advantageously but not necessarily closer to the ear than the central loudspeaker array 20. Thereby, it is also ensured that a further optional condition, namely that the additional loudspeaker 30a is arranged closer to a listening position 12a compared to the other listening positions 12b-12d is fulfilled.

[0047] As illustrated herein, the additional loudspeaker 30a generates a beam 32aL allocated to the one (left) ear of the listener at a listening position 12a, while the other (right) ear is exposed to sound by the beam 22aR (generated by the loudspeaker array 20). Thus, in the illustrated embodiment, it is possible to generate stereo at the listening position 12a. The usage of the additional loudspeaker 30a is not limited to stereo, in that way, the additional loudspeaker 30a can generally serve to support sound exposure at the listening position 12a (mono with level increase). Here, it is advantageous that the additional loudspeaker 30a is positioned close to the listening position, such that the principles of sound level drop with distance are used, which has the effect that the sound level of the additional loudspeaker 30a is louder in the allocated listening zone 12a than in the other listening zones 12b-12d. This contributes, in particular, to an increased acoustic separation of the sound zones 12a-12d. Generally, the advantages of an additional loudspeaker 30a can be that the sound quality and the spatial impression for the allocated sound zone are improved by using psychoacoustic effects. Generally, it should be noted that by arranging sound transducers 20 and 30a, respectively, as close as possible to the listening position (here, 12a), cf., e.g., sound transducers 20 and 30a with regard to the listening position 12a, the proportion of direct sound increases, such that reflections are hidden as far as possible or are negligible.

[0048] FIG. 1d shows the vehicle interior 10 with a loudspeaker system 1 in a side view. Here, the listening position 12b and the listening position 12d are illustrated, where it can further be seen that the loudspeaker array 20 is arranged centrally above the listening positions 12d and 12b (i.e. in the roof lining). For the (rear) listening position 12d, to which the beam 22 is oriented, an additional loudspeaker 30d is provided (here, in the rear shelf for generating the beam 32d) which corresponds to the additional loudspeaker 30a of FIG. 1c as regards to characteristics and purpose.

[0049] According to further embodiments, as also illustrated in FIG. 1d, it is possible that a structure-borne sound exciter is provided as an additional loudspeaker per listening position, here 12d and 12b. In the illustrated embodiment, the seat for the listening position 12b includes the structure-borne sound exciter 35b while the seat for the listening position 12d includes the structure-borne sound exciter 35d. Each of these structure-borne sound exciters 35b and 35d is mechanically firmly connected to the seat (seat frame or headrest) for the listening position 12b and 12d, respectively, (e.g. via the foot space) or generally allocated to the location of the listener and configured to output the structure-borne sound 36b and 36d, respectively, such that the same reaches the respective listener. These structure-borne sound transducers 35b and 35d are particularly suited as support in the bass range where sound reproduction with small arrays (due to the limited array size) could not be sufficiently focused. By optional sound decoupling means, it can be ensured that the structure-borne sound 36d and 36b, respectively, cannot be perceived in other listening zones, e.g. 12a and 12c, which again contributes to increasing the acoustic separation between the sound zones 12a-12d.

[0050] FIG. 2a shows a loudspeaker array 50 with a plurality of sound transducers 52a-52d of type A and a plurality of sound transducers 54a-54d of type B. The sound transducers of type A differ in particular with regard to their size and hence typically but not necessarily, in their transferable frequency range from the electroacoustic sound transducers 54a-54d of type B (B for the treble range, e.g. >1000 Hz or 500 Hz; A for the bass range, e.g. <2000 Hz or <500 Hz). Further, the directional characteristic of the sound transducers 52a-52b of type A can also differ from the sound transducers 54a and 54b of type B. The sound transducers 52a-52d and 54a-54b are arranged in the form of a linear sound transducer array and comprise, all in all, less sound transducers than a structure with 2 parallel arrays of type A and B of the same length. These array arrangements 50 shown in FIG. 2a in line shape can be used as arrays for the loudspeaker systems 1, 1 or 1 of FIG. 1a-1d.

[0051] Even when the array discussed with regard to FIG. 2a has been illustrated in the form of A, B, A, B, A, B, A, B, the basic idea of alternate arrangement can also be transferred to sound transducer arrays having more than two different sound transducer types, such that for example also a sound transducer arrangement of A, B, C, A, B, C would be possible. A further possible alternative would be the sound transducer arrangement A, A, B, B, A, A, B, B.

[0052] A loudspeaker array 60 where further advantages become obvious will be discussed with regard to FIG. 2b. Concerning the loudspeaker array 60, it should also be noted that the same could also be used for loudspeaker systems outside the motor vehicle sector, or that merely the array 60 provides advantages. FIG. 2b shows a loudspeaker array 60 with the sound transducers 52a-52f (type A) and the sound transducers 54a-54f (type B). Here, the sound transducers 52a-52f and 54a-54f are arranged along the line of the array 60 such that an average distance d.sub.B of the sound transducers 54a-54f is smaller than an average distance d.sub.A of the sound transducers 52a-52f, cf. d.sub.B<d.sub.A. Further, it can also be determined that the average distance of the sound transducer of type B d.sub.B is smaller than the medium average distance d.sub.AB of all used sound transducers (cf. FIGS. 2a and 2b). Such a formation of the average distance d.sub.B in relation to the average distance d.sub.A can be realized by the respective order of the different sound transducers 52a-52f and 54a-54f, respectively.

[0053] As illustrated in FIG. 2b, a possible mode of realization would be the combination of the sound transducers in the form of A, A, B, A, B, B, B, A, B, A, A. In the array 60 illustrated in FIG. 2b, four sound transducers of type B, cf. 54b-54e are arranged in the interior 60i, which are encompassed by one sound transducer of type A (cf. 52c and 52d) each per side, wherein this arrangement is again encompassed by one sound transducer of type B (cf. 54a and 54f) each. This entire sound transducer arrangement is then again encompassed by two sound transducers of type A (cf. 52a, 52b, 52e and 52f) each per side. In other words, such a distribution can also be described as logarithmic or at least approximately logarithmic.

[0054] In this sound transducer arrangement of the array 60, it can be ensured that a high density of sound transducers of type B is provided in the interior (cf. area marked by reference number 60i), which operate in the treble range and, by tendency, are characterized by a good adjustment of the radiation characteristic. This applies in particular compared to the exterior or the exterior areas 60a, respectively. By such an arrangement, the two conditions inherent to the system can be taken into account, namely that the loudspeaker array 60 should be greater than the wave length for focused radiation, which is in particular problematic for bass reproduction due to the size of the sound transducers 54a-54h and that simultaneously the distance of adjacent loudspeakers should be smaller than the wave length for error-free reproduction, which is in particular problematic for treble reproduction due to the size of the sound transducers 52a-52h.

[0055] The principle of the quasi-logarithmic arrangement described in FIG. 2b can also be transferred to planar sound transducer arrays as shown in FIG. 2c. FIG. 2c shows an array 70 with a central sound transducer 54e of type B surrounded by all in all 8 sound transducers 54a-54i of type B all around (i.e. one on each side). In that way, the electroacoustic sound transducers 54a-54d generate a 33 field of electroacoustic sound transducers 54a-54d of type B. With regard to the entire sound transducer arrangement 70, this 33 field of sound transducers 54a-5ei is in the center of the array area 70. This center is indicated by reference number 70i. The 33 field of sound transducers 54a-54i is again surrounded by the sound transducers 52a-52h of type A all around.

[0056] In this embodiment, the average distance of the sound transducers 54a-54i referred to as density due to the two-dimensionality is smaller than the average distance of the sound transducers 52a-52h in the exterior 70a. This means that the density in the interior 70a compared to the density of the exterior 70a (defined by the number of sound transducers 52a-52h and 54a-54i per area) is higher. Even with this area arrangement, a small sound transducer distance to the highly focused radiations in the sound transducers 54a-54i for high frequency ranges can be obtained and a design-induced greater sound transducer distance (to the focused radiation) for the lower frequency ranges (cf. sound transducers 52a-52h).

[0057] Even when the planar sound transducer arrangement has only been explained in the shape of a checker-board pattern of the sound transducer array 70, it should be noted that also other planar arrangements, e.g. concentric arrangements having a concentration of sound transducers of a specific type (B) in a specific region, e.g. in the center (70i) would be possible where the sound transducer density varies across the area. The arrangement of the sound transducers of type A/B does not necessarily have to be symmetric. In that way, also, asymmetric arrangements, i.e. slightly offset treble array (cf. 54a-54i) in the center 70i of the bass array (cf. 52a-52h) would be possible. Advantageously, reduction of artefacts in the radiation function due to discontinuity points can be obtained in that way. The reason for such effects is, for example, edge reflection in tweeters that are placed centrally on the front of the housing.

[0058] The loudspeaker arrays 60 and 70 can be used as arrays for the embodiment of FIG. 1a-d and have, compared to the loudspeaker array of FIG. 2a, advantages with regard to directivity, in particular when beamforming for adjusting the directional characteristic both in the low frequency and in the high frequency range and can above that contribute to the prevention of spatial aliasing effects.

[0059] The concentration of sound transducers of type B in the center 60i and 70i and of sound transducers of the type A in the exterior 60a and 70a obtained by the sound transducer arrays 60 and 70 can also be obtained by a sound transducer arrangement having two levels as described with reference to FIG. 2d.

[0060] FIG. 2d shows a loudspeaker array 80 having a plurality of sound transducers 52a-52h (type A) arranged linearly (directly) beside one another in a first plane. Further, the sound transducer array 80 includes a plurality of sound transducers 54a-54h (type B) that are also linearly arranged beside one another (abutting). These two sound transducer types 52a-52h and 54a-54h are arranged in two different planes, i.e. behind one another or also offset and above one another, respectively. Both arrangements of the line arrays have in common that the line on which the sound transducers 52a-52h and 54a-54h are arranged is equal, meaning parallel. Thus, despite the direct juxtaposition of the sound transducers of the same type 52a-52h and 54a-54h, respectively, it is possible that the average distance d.sub.B of the sound transducers of type B (54a-54h) is smaller than the average distance d.sub.A of the sound transducers of type A (52a-52h).

[0061] It should be noted that it is insignificant for this embodiment whether the sound transducers of type A are arranged in the first or second plane and vice versa also whether the sound transducers of type B are arranged in the first or second plane.

[0062] Optionally, however, it is important that the sound transducers of type B arranged with a low average distance d.sub.B are positioned in the center of the sound transducer arrangement of type A, such that this embodiment of the loudspeaker array can also obtain a concentration of sound transducers for the high-frequency range in the center.

[0063] In further embodiments, it would also be possible that further sound transducers, i.e. sound transducers of type C, are arranged in a third plane.

[0064] With reference to the loudspeaker arrangements of FIG. 2a-2d it should be noted that complex directional characteristics, can be allocated to the individual transducers 52a-52h and 54a-54h, respectively, e.g. by sound guides or by the sound transducer itself.

[0065] A further embodiment relates to a combination of several line arrays, such as arrays 50 and 60, such that a planar loudspeaker array is formed. The line array 50 or 60 can have a different number of sound transducers, such that, for example also different lengths of the line arrays result. Further, it would also be possible that the sound transducer distances per line array vary, e.g. based on the fact that different sound transducer types can be used.

[0066] According to further embodiments, each line array can by itself include different sound transducer types, wherein the combination of line arrays having one type per line array is advantageous. An embodiment is characterized in that two line arrays with the sound transducer type A enclose three line arrays having the sound transducer type B. In that way, a planar loudspeaker array is formed, where a specific type of sound transducers is concentrated in the center.

[0067] With reference to FIG. 3, an extension for the above loudspeaker arrays will be described below, wherein the extension is not limited to such arrays or the motor vehicle sector.

[0068] FIG. 3 shows a loudspeaker array 90, here implemented as combination of eight sound transducers 52a-52h of the same type. Each of these sound transducers 52a-52h or, to be more accurate, the membrane 56 of the sound transducers 52a-52h, is coupled to a sound guide 92a-92h on its radiation side. These sound guides 92a-92h are funnel-shaped and optionally bent elements, such that the sound outlet openings (cf. reference number 94) of the sound guide 92a-92h are smaller (in all or at least one dimension) than the sound inlet openings (cf. reference no. 56) on the side of the electroacoustic sound transducers 52a-52h. The funnel of the sound guide 92a-92h is configured such that the sound input 56 is offset compared to the sound outlet openings 94, wherein, depending on the combination with a sound transducer 52a-52h, a different offset ratio is used, such that the total area of the sound outlet openings can be reduced as a whole.

[0069] Hereby, the sound outlet openings 94 of the sound guides 92a-92h can be arranged tightly beside one another with an average distance d.sub.S. As a consequence, despite the loudspeaker array 90 with large-scale extension, a very small average distance d.sub.S is obtained between the sound outlet openings 94 (in particular compared to the average distance d.sub.A), which results in an improved adjustable directional characteristic (due to the reduction of the sound radiation area by the compact distance d.sub.S of the sound outlet openings 94 and due to the reduced virtual sound transducer distance d.sub.S, respectively) and better positioning options of the arrays (e.g. within the vehicle).

[0070] The combination of the sound guide 92a-92h with one of the loudspeaker arrays 50, 60, 70 or 80 is possible, such that the sound guide can also be used for the embodiments of the loudspeaker system 1, 1 or 1 of FIG. 1a-1d. Thereby, it is also possible (as already indicated above) to configure the sound guide 92 such that the actual sound transducer array 90 (or also 50, 60, 70, 80) is installed at a specific position within the car (e.g., in the trunk), e.g. due to lack of space, and the sound guide guides the sound to the respective sound outlet point, e.g. in the roof, which allows space-saving installation.

[0071] With regard to FIG. 1, it should be noted that the arrangement of the loudspeakers and loudspeaker arrays of the loudspeaker system, respectively, can also be carried out with a predetermined orientation, e.g. onto the listening positions 12a-12d, such that a directed radiation per sound transducer is possible, which contributes to a reduction of the influence on room acoustics in the sound zones by the position of the loudspeakers.

[0072] According to further embodiments, also, a signal control apparatus can be provided which controls the array 20 and the extended arrays 50, 60, 70, 80 90, respectively, according to the above-described principles (cf. mono reproduction of the listening zone 12a-12d or stereo reproduction of the listening zone 12a-12d) and hence allows the formation of the respective number of highly focused sound radiation beams 22a-22d, 22aL, 22aR.

[0073] With reference to FIG. 1, it should further be noted that user-specific signals could also mean the fading-in of other audio information, such as in infotainment signals or telecommunication audio, into a specific listening zone, e.g. the driver listening zone 12a.

[0074] According to further embodiments, the loudspeaker system can include a frequency-separating means or a processor that is configured to provide the central and higher frequencies of the input signal, when the same includes only listening content (i.e. content for a person at the respective listening/seating position), to the array, e.g. in the way that beamforming can be performed, and to output the lower frequencies at the structure-borne sound transducer of the respective seating position. In the case that the audio content to be reproduced includes several parallel contents, e.g. intended for different listening/seating positions), the frequency-separating means and the audio processor, respectively, are configured to provide the central entire frequencies of all audio content to be reproduced to the array, in the way that the audio content can be reproduced separately for the different listening zones at the different listening positions by means of beamforming, while the lower frequencies are split off and passed on to the different structure-borne sound transducers of the different seats and listening positions, respectively. All in all, this offers the advantage that central and higher frequencies can be reproduced in a directed manner for the different listening positions by means of the array, while the lower frequencies are represented only locally via the structure-borne sound transducer. The reason for this procedure is that in particular the low frequencies cannot be directed so well via arrays, such that separation of the same by means of beamforming frequently causes problems. By using the structure-borne sound transducers explicitly allocated to the individual seating and listening positions, respectively, no overlap of the sound signals of these sound transducers will occur.

[0075] Further embodiments provide a loudspeaker array having a plurality of first electroacoustic sound transducers arranged on a first line, and a plurality of second electroacoustic sound transducers arranged on the first line or a line parallel to the first line. Here, an average distance (d.sub.B) between the first electroacoustic sound transducers is smaller than an average distance (d.sub.B) between the second electroacoustic sound transducers.

[0076] Further embodiments provide a loudspeaker array having a plurality of first electroacoustic sound transducers arranged in a first planar area and a plurality of second electroacoustic sound transducers arranged in the first planar area. Here, an average density of the first electroacoustic sound transducers is smaller than an average density of the second electroacoustic sound transducers.

[0077] Further embodiments provide a loudspeaker array having a plurality of electroacoustic sound transducers coupled to first sound guides for sound output in a first area, wherein each sound guide includes a sound outlet opening. Here, the plurality of sound outlet openings is arranged such that an average distance (d.sub.S) between the sound outlet openings is smaller than a possible average distance (d.sub.A) between the juxtaposed electroacoustic sound transducers.

[0078] With reference to the loudspeaker array 20 of FIG. 1a-1d, it should be noted that the geometrical orientations of the sound transducers 20a-20h in the loudspeaker array 20 illustrated in the schematic drawings is hypothetical and does not necessarily reflect reality. Thus, the orientations of the individual sound transducers 20a-20h can deviate accordingly or can even vary from position to position (strongly tilted to the first side, tilted to the first side, towards the bottom, tilted to the second side, strongly tilted towards the second side).

[0079] While this invention has been described in terms of several advantageous embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.