Method and device for sonicating at least one audience range

Abstract

The invention relates, inter alia, to a method for sound reinforcement of at least one audience area (3) by means of at least one sound transducer arrangement (1) with a plurality of sound transducers (9), wherein the individual sound transducers (9) of the at least one sound transducer arrangement (1) each emit elementary waves (8) which superimpose to form a common wavefront (4), characterized in that a) the at least one sound transducer arrangement (1) and the at least one audience area (3) are geometrically linked to each other by a coordinate system (2) and b) a spatial assignment exists between the physical positions of the individual sound transducers (9) in the at least one sound transducer arrangement (1) and position vectors si for defining coordinates in the area of ​​the at least one sound transducer arrangement (1),and furthermore c) an assignment of points of the coordinate system (2) to points in the at least one audience area (5) according to a position vector ri, wherein d) direction vectors, in particular normalized direction vectors (61) d^i=ri−siri−si, result in the coordinate system (2) and wherein e) depending on the spatial assignment of the position vectors si and the sound transducers (9), delay times τj for the sound transducers (1) are determined, with which elementary waves (8) are radiated by the sound transducers (9), wherein e) the delay times τj of the sound transducers (9) are each chosen such that the local direction (50) of the common wavefront (4) corresponds to the direction of the direction vector, in particular the normalized direction vector (61) d̂i.

Description

[0001] The invention relates to a method for sound reinforcement of an audience area with the features of claim 1, a method for determining delay times τ i for operating sound transducers with the features of claim 16, a computer program product with the features of claim 30 and a device for providing sound to at least one audience area with the features of claim 31.

[0002] According to the principle of wave field synthesis (AJ Berkhout, A Holographie Approach to Acoustic Control, J.Audio Eng.Soc, Val. 36, No. 12, 1988), a large number of transducers generate a wave front that supplies a given audience area with a very uniform level of high audio quality, without undesirably illuminating adjacent reflecting surfaces.

[0003] As the size of the audience areas at large events grows, so do the demands placed on sound reinforcement systems. Often, the differences in sound pressure between individual spectator seats are intolerable due to poorly directional sound radiation. Reproduction, frequency response, and speech intelligibility suffer due to level drops, airborne sound insulation, and unwanted reflections.

[0004] For this reason, loudspeaker arrangements consisting of multiple individual sound sources direct the sound more strongly toward the more distant audience areas. A typical application is so-called line arrays, which are arranged, for example, to the left and right above a stage front. Their curvature is tuned to the audience area so that the radiated wavefront is directed in the elevation plane toward the more distant audience areas. This creates a virtually cylindrical wave around this part of the loudspeaker arrangement.

[0005] The surface area of ​​a cylinder grows linearly with its radius, which is why the sound pressure decreases by 3 decibels for every doubling of the distance.

[0006] In the lower part of the transducer array, the greater curvature of the transducer surfaces results in a larger vertical aperture angle. The wavefront in this area is almost a spherical section. The surface area of ​​a sphere, which grows quadratically with the radius, results in a sound pressure drop of 6 dB for every doubling of distance. Due to the rapid sound pressure drop in the near field and the longer-reaching cylindrical wave for the distant seats, the differences in sound pressure between the front and rear audience areas are significantly reduced.

[0007] In recent years, arrays with electronic control of the individual transducers have also been used. Each transducer has its own amplifier, controlled by a signal processor. Mathematical methods allow for a radiation pattern that is significantly better adapted to the audience area than would be possible with the mechanical alignment of individual transducers. The curvature of the transducer array can be simulated and electronically adjusted according to Huygens' principle, with minimal delays in the control of the individual transducers. However, these possibilities are limited to the elevation plane with the available arrays.

[0008] Because the directivity can only be adjusted in the elevation plane, even with this improved dispersion, the sound field remains only roughly tailored to the given audience area. In the azimuth plane, the dispersion is determined only by the mechanical alignment of the loudspeaker array. Adaptation to the audience area can only be achieved by selecting loudspeaker elements with wider or narrower horizontal directivity.

[0009] Loudspeaker arrays, such as those available for audio reproduction based on the principle of wave field synthesis (as described, for example, in WO2015036845A1), are significantly more flexible. Here, too, each transducer is driven by a separate power amplifier. According to Huygens' principle, the superposition of the elementary waves of each individual transducer creates a wavefront that reconstructs a spherical section of the wavefront of a real sound source. The center of this spherical section is the virtual sound source of the wave field synthesis. The boundaries of the spherical section are determined by the size of the transducer array in conjunction with the position of the virtual sound source.

[0010] The aim of the proposed solution is a method for sound reinforcement of an audience area by means of a sound transducer arrangement, which results in an improved adaptation of the radiation characteristics to the audience area.

[0011] The proposed solution relates to a method for providing sound to at least one audience area using a sound transducer array comprising a plurality of transducers. During operation, the individual transducers of the at least one transducer array emit elementary waves that overlap to form a common wavefront. Whenever reference is made below to the emission of elementary waves from the transducers, the acoustic center of the transducers is meant.

[0012] The at least one sound transducer arrangement and the audience area are assigned to a common coordinate system, in particular a Cartesian coordinate system.

[0013] As will become clear below, the coordinate system on the side of the at least one sound transducer arrangement serves in particular to provide starting points for position vectors s i which together with direction vectors r i determine the sound radiation from the at least one sound transducer arrangement. The coordinate system thus links the at least one sound transducer arrangement and the at least one audience area.

[0014] Between the position vectors s i and the physical positions of the transducers are spatially related. In the simplest case, the acoustic centers of the transducers are located at the origin of the position vectors s i . However, it is also possible that the transducers are not exactly positioned at the origins of the position vectors s i If the positions of the acoustic centers of the transducers deviate from the intersection points of the auxiliary grid, the associated change in delay time and level can be corrected by spatial interpolation or other methods. The position vectors s i can be stored in the form of a list, for example.

[0015] By introducing the coordinate system, points in the audience area and points on the at least one sound transducer arrangement - and thus indirectly also the sound transducers themselves - can be easily related to each other geometrically, for example when calculating the distance of a sound transducer to a point in the audience area.

[0016] The method is based on an assignment of points of the coordinate system to points in at least one audience area and assigns a position vector accordingly r i The position vector r i thus points to a specific location in the audience area 3.

[0017] From the position vectors s i , from which the positions of the individual sound transducers can be determined directly or indirectly, direction vectors, in particular standardized direction vectors d̂ i = r i − s i r i − s i determine the radiation direction of the wavefront in the area of ​​the respective sound transducers.

[0018] Now, depending on the spatial assignment of the position vectors s i and the transducer delay times τ j for the sound transducers, which then emit acoustic elementary waves. The delay times τ j The transducers are each selected so that the local direction of the common wavefront corresponds to the direction of the direction vector, in particular the normalized direction vector d̂ i corresponds.

[0019] The sound transducers of the at least one sound transducer arrangement are thus each with a certain delay time τ j operated. The delay time τ j of a transducer determines the time of generation of an elementary wave at the respective transducer. In particular, the delay times τ j of the individual transducers relative to the input signal. In other words, each transducer is assigned an individual delay time τ j The delay times of the individual transducers can generally differ, but some transducers can also be assigned the same delay time τ j operated.

[0020] The total delay times with which the individual transducers of the transducer array are operated influences the shape of the common wavefront, which is composed of the elementary waves generated by the individual transducers. In particular, the total delay times τ j the shape of the common wavefront can be determined.

[0021] In particular, by choosing certain delay times τ j produce complex wavefronts. The result is different delay times τ j in the sound transducer arrangement a correspondingly shaped wavefront, e.g. with different curvatures. The wavefront formed by the elementary waves is therefore no longer a spherical section, as generated by a virtual sound source with a two-dimensional wave field synthesis sound transducer arrangement. Depending on the shape and size of the coverage area (i.e. of at least one audience area), stronger curvatures and more flatly curved areas result. In the direction of the most distant audience seats, the convex curvature of the wavefront is usually less pronounced; a stronger curvature towards the front audience seats causes the sound pressure level to fall more quickly with distance and distributes the energy over a larger audience area.

[0022] The delay times τ j of the individual transducers can be determined in such a way that the common wavefront adapts to the geometry of the audience area. In particular, the delay times τ j The local directions of the wavefront are controlled. The resulting, irregularly shaped wavefront is assigned, in principle, the same number of grid points (i.e., the coordinate system in the area of ​​the transducer array) of the transducer array and thus also of transducers for the same size audience area. In this respect, such a wavefront differs fundamentally from the spherical section of a point-like virtual sound source in wave field synthesis, in which the audience area supplied by the same number of transducers increases steadily with distance.

[0023] The local direction of the common wavefront at a position on the wavefront describes the direction in which the common wavefront propagates at that particular position. The local direction of the common wavefront can be described by the direction vector that is perpendicular to the respective point on the common wavefront. The direction vector describes a local propagation direction of the common wavefront when the wavefront moves perpendicular to the direction vector.

[0024] An adaptation of the common wavefront to the geometry of at least one audience area is made possible by a definable assignment that assigns the position vectors s i (which can be assigned to individual surge converters, for example) each have a position in the audience area corresponding to a position vector r i The respective assignment results in normalized direction vectors d ^ i = r i − s i r i − s i . The delay times τ j are then chosen so that the local direction of the common wave front at the position in the audience area, which is determined by the position vector r i is described, the direction of the direction vector d̂ i In particular, local propagation directions of the common wavefront are given by the normalized direction vectors d̂ i given.

[0025] The sound transducers of the at least one sound transducer arrangement can be arranged on or in a plane. Alternatively, the sound transducers of the sound transducer arrangement can be arranged on or in an at least partially curved surface. The arrangement can, for example, be grid-like. In particular, the distances between the sound transducers can be uniform. For example, the distances in a first direction, in particular in the vertical direction, and / or the distances in a second direction, in particular in the horizontal direction, can each correspond to one another or result in a regular sequence of distance sizes. The geometric shape in or on which the sound transducers are arranged can be complex. For example, the sound transducers can be located in one area on a flat surface, while other sound transducers of the same sound transducer arrangement are located on a curved surface.Different parts of the surface can also have different radii of curvature.

[0026] Alternatively, the sound transducers of the at least one sound transducer arrangement are arranged in a three-dimensional area, in particular a space. The arrangement of the individual sound transducers can be determined based on a reference surface, for example, a plane or a curved surface, wherein at least a subset of the sound transducers of the at least one sound transducer arrangement is arranged on the reference surface, and the positions of the remaining sound transducers of the at least one sound transducer arrangement can be determined by a spatial offset into the three-dimensional area.

[0027] The operation of the transducer - which corresponds to the position vector s i is assigned - with delay time τ j can be controlled by a computer system. In particular, the control can be carried out with a delay time τ j be digitally influenced or caused by digital control. The delay times can be in the order of milliseconds. For neighboring transducers, the time difference is usually only a few microseconds, so the overall system requires a very stable system clock.

[0028] Additionally or alternatively, the delay time with which a transducer operates can be influenced mechanically or geometrically. For example, the delay time of a transducer can be controlled by a spatial offset, particularly in the radiation direction of the transducer array, relative to other transducers in the transducer array.

[0029] The audience area can have at least partially a flat or concave and / or at least partially a convex shape. The audience area can be described as a continuous area or as a discontinuous area consisting of at least two connected parts. An example of an audience area composed of multiple areas is the main hall of the Berlin Philharmonic Hall or an opera hall with multiple tiers. The audience area can also be represented by a set of coordinate points.

[0030] In the coordinate system, the position vectors s i , which are assigned to the transducers of the transducer array, form a regular grid.

[0031] Additionally or alternatively, the position vectors r i a regular grid on the reference area R assigned to the public area.

[0032] The assignment that each position vector s i in the transducer array a point in the audience area corresponding to the position vector r i can be determined by means of connecting lines from the transducer arrangement to the audience area. In particular, the connecting line can be a half-line starting from the position vector s i which intersects the audience area or the reference surface R assigned to the audience area. The sound transducer can then be assigned a position vector r i which results from the intersection point of the half-line with the audience area or the reference area R assigned to the audience area.

[0033] Additionally or alternatively, the levels at which the sound transducers of the at least one sound transducer arrangement are operated can be adjusted by means of a relative amplification factor d̂ n be determined, in particular based on the provision d̂ n = d̂ i · n i , where n i the normal to the reference surface S at the position vector s i describes.

[0034] By operating the transducers according to the relative gain factors d̂ n ensures that the sound pressure level at the receiver position r i independent of the angle of the direction vector d i to the normal n i This ensures a homogeneous volume throughout the audience area.

[0035] Furthermore, the proposed solution includes a method for determining delay times τ j for a sound transducer arrangement with a plurality of sound transducers j for generating elementary waves according to the delay times τ j for sound reinforcement of at least one audience area.

[0036] The method comprises the steps of determining a coordinate system by which the at least one sound transducer arrangement can be approximately used as a reference surface S and the audience area are approximately described as a reference surface R; the determination of position vectors s on the reference surface S of the at least one sound transducer arrangement, from which the positions of the sound transducers of the at least one sound transducer arrangement can be determined; the determination of standardized direction vectors d̂ starting from the position vectors s, where the normalized direction vectors d̂ directed to the reference area R of the public area and the determination of delay times τ j for transducers j , so that the elementary waves of the transducers of the transducer arrangement during operation according to the delay times τ j superimpose to form a common wavefront, where the normalized direction vectors d̂ describe local propagation directions of the common wavefront.

[0037] In other words, the common wavefront propagates essentially perpendicular to the normalized direction vectors d̂ In this way, the normalized direction vectors describe d̂ the propagation path of the common wavefront. In particular, the common wavefront is determined by a suitable choice of the normalized direction vectors d̂ adaptable to the geometry of the audience area.

[0038] To adjust the sound levels, the relative gain factors d̂ n for at least a subset of the position vectors s according to the rule d ^ n = d ^ ⋅ n where n is a normal to the reference surface S the transducer arrangement at the point determined by the position vector s and d̂ the normalized direction vector starting from the position vector s.

[0039] The position vectors s may correspond entirely or partially to the positions of the sound transducers on the sound transducer arrangement, in any case there is a correlation between the physical positions of the individual sound transducers in the at least one sound transducer arrangement and the position vectors s i to determine coordinates in the area of ​​at least one sound transducer arrangement, a spatial assignment.

[0040] The number of position vectors s can correspond to the number of transducers in the transducer array or can be different. In particular, the number of position vectors s can be higher than the number of transducers in the transducer array.

[0041] The position vectors s can describe intersection points of an auxiliary grid 5 defined on the reference surface S of the at least one sound transducer arrangement. However, position vectors s do not have to lie at all intersection points of the auxiliary grid 5. The auxiliary grid 5 can, for example, describe a rectangular plane.

[0042] The number of grid lines in the horizontal and / or vertical directions can each correspond to a number of rows and / or columns of transducers in the transducer array. However, the number of grid lines in the horizontal and / or vertical directions can also be greater than the number of rows and / or columns of transducers in the transducer array.

[0043] The method may further include a determination of position vectors r on the reference surface R of the audience area, wherein a position vector r is assigned to each position vector s. The assignment can be made by means of a connecting line from the position vector s to the position vector r on the basis of which the normalized direction vector d̂ In particular, the direction vector d̂ each using the calculation rule d ^ = r − s r − s be determined.

[0044] In one embodiment, the entirety of the connecting lines is designed such that they do not cross or overlap in pairs. In particular, no connecting line intersects the other connecting lines.

[0045] The assignment of the position vectors s to the position vectors r can be done automatically, especially using a 3D CAD file of the audience area. This can be done using a suitable mapping process. In particular, points and / or areas of the reference surface of the audience area can be omitted during the mapping, for example, those corresponding to areas of the audience area that should not be affected by the common wavefront.

[0046] The position vectors r can be evenly distributed over the reference surface R of the audience area. This allows them to correspond to evenly distributed points within the audience area. A uniform distribution of the points is ensured, for example, by ensuring that any two adjacent points are the same distance apart.

[0047] The reference area R of the public area can be described by an auxiliary grid. The position vectors r can at least partially correspond to intersection points of the auxiliary grid.

[0048] Likewise, the reference surface S The acoustic transducer arrangement can be described by an auxiliary grid 5, on which the position vectors s correspond at least partially to intersection points. Such an auxiliary grid is particularly important for numerical treatment, since it allows, for example, numerical integrations using the trapezoidal rule to be easily performed.

[0049] Auxiliary grids on the reference surface S of the at least one sound transducer arrangement and auxiliary grids on the reference surface R of the audience area can be interconvertible. In particular, they can have the same number of lines in the horizontal and / or vertical plane. By connecting the intersection points of the auxiliary grids, a suitable connection can be created between the reference plane S of at least one sound transducer arrangement to the reference plane R of the audience area.

[0050] The reference surface S of the at least one sound transducer arrangement can be a plane or, for example, an at least partially curved surface. In particular, a curvature of the reference surface S the transducer arrangement in the horizontal direction from a curvature in the vertical direction.

[0051] In one embodiment, the reference surface S the transducer arrangement using coordinatess ( u, v ) = [ x ( u, v ) y ( u, v ) z ( u, v )] parameterized, where u and v are real, continuous variables.

[0052] To determine the respective individual delay times τ j for transducers j can initially be a scalar-valued function of delay times τ ( u, v ) for a finite set of position vectors of the form s = s ( u , v ) and then the determination of the delay time τ j for transducers j at least partly by interpolations of at least two values ​​of the form τ ( u, v ) take place.

[0053] The delay times τ ( u, v ) are in one embodiment by means of numerical integration of the discrete 2D vector field [Δ u τ Δ v τ ] can be determined. The delay differences Δ u τ in u - Direction or Δ v τ in v - Direction given by Δ u τ = d ^ u c Δ u or Δ v τ = d ^ v c Δ v , where Δ u and Δv are each discrete step sizes in u - direction or v - direction, c describes the speed of sound and where d̂ u and d̂ v by the scalar products d ^ u = d ^ ⋅ s u or d ^ v = d ^ ⋅ s v , are given, where d̂ the normalized direction vector starting from the position vector s = s ( u , v ) describes and s u and s v Tangent vectors to the reference surface S starting from the position vector s = s ( u , v ) describe.

[0054] The tangent vectors s u and s v are given by the partial derivatives s u = ∂ s ∂ u = ∂ x ∂ u ∂ y ∂ u ∂ z ∂ u or s v = ∂ s ∂ v = ∂ x ∂ v ∂ y ∂ v ∂ z ∂ v .

[0055] In other words, it can be used in a method for determining the delay times τ ( u, v) first the two-dimensional discrete vector field [Δ u τ Δ v τ ] in accordance with the regulations Δ u τ = d ^ u c Δ u or Δ v τ = d ^ v c Δ v , based on tangent vectors s u and s v the reference surface S the transducer arrangement, the standardized directional vectors d̂ and the speed of sound c. The vector field can then be integrated using a numerical integration method. The function obtained by the integration τ ( u, v) then describes the desired delay times.

[0056] The values ​​of the function τ ( u , v ) describe the delay times at the position vectors s(u, v). For each individual combination of the parameters u and v defined s ( u, v ) own position s i . The delays at the driver positions can then be determined by spatial interpolation.

[0057] The calculated time is then executed at the time of the nearest sample determined by the sampling frequency of the overall system.

[0058] In particular, the desired delay times are described by a function τ ( u, v), whose gradient is the two-dimensional vector field [Δ u τ Δ v τ ], where the components Δ u τ and Δ v τ as given above. A wavefront can be thought of as a kind of relief that assigns a height at each intersection point of the grid. Then, the gradient at that point is a vector pointing in the direction of the greatest elevation increase. The magnitude of this vector indicates the greatest gradient at that point.

[0059] The speed of sound c can certainly depend on the location, for example, if a higher temperature prevails at a higher level of the sound propagation range, which influences the speed of sound. The speed of sound can also depend on the location, which is then taken into account in the calculation.

[0060] The numerical integration method may include the composite trapezium method, the Simpson method, the Romberg method, or the more advanced inverse gradient method.

[0061] In case the reference surface S the transducer arrangement using a function s ( u , v ) = [ x ( u, v ) y ( u, v ) z ( u, v )] is parameterized as described above, the normal n to the reference surface is Sthe sound transducer arrangement, which can be used to determine the sound level correction, at the point defined by s = s ( u , v ) described point given by the cross product of s u and s v n = s u × s v , where s u and s v are given by the partial derivatives as described above.

[0062] Embodiments are described below by way of example with reference to figures. Fig. 1 a schematic representation of the wavefront of a virtual sound source of wave field synthesis in a two-dimensional sound transducer arrangement; Fig. 2 a schematic representation of the wavefront of a wavefront shape of a two-dimensional sound transducer arrangement adapted to the audience area according to the invention; Fig. 3 the determination of normal vectors on a curved reference surface of a sound transducer arrangement; Fig. 4 the assignment of the auxiliary grid of a transducer arrangement to an auxiliary grid in the audience area; Fig. 5 the formation of a local directional vector of the wavefront, which originates from a sound transducer from surrounding elementary waves and shows the audience area; Fig. 6 the formation of a normalized direction vector of length one; Fig. 7 an embodiment in which the audience area is divided into individual sub-areas with different signal content; Fig. 8 adapted transducer configuration for a non-variable audience area; Fig. 9 an embodiment with a mechanically curved transducer surface.

[0063] In Fig. 1 a given audience area 3 is shown, which is to be sound-exposed with a planar sound transducer arrangement 1 according to the principle of wave field synthesis (WFS).

[0064] During operation, the sound transducers of the sound transducer arrangement 1 generate elementary waves 8, which overlap to form a common wavefront 4. The common wavefront 4 is configured as if it emanates from a virtual sound source 12. Accordingly, the surface of the wavefront 4 formed from the elementary waves 8 of the sound transducers 9 corresponds to a sphere. For illustrative purposes, the common wavefront 4 is divided into rectangles 105, which represent the proportions of elementary waves 8 generated by approximately the same number of sound transducers of the sound transducer arrangement 1 on the common wavefront 4.

[0065] In the spherical section 4, the respective sub-area 105 assigned to a given number of transducers of the transducer array 1 is approximately the same size. Accordingly, the sound pressure is evenly distributed across the surface of the wavefront 4 at the same time.

[0066] However, the audience areas 106 assigned to these subsections have very different areas, over which the same energy of the assigned spherical wave section is distributed. The sound pressure levels in the various parts of audience area 3 vary accordingly.

[0067] The virtual sound source 12 is in Fig. 1 located behind the sound transducer array 1. The position of the virtual sound source 12 determines both the curvature of the common wavefront 4 and the direction in which it propagates. If the virtual sound source 12 is positioned close to the sound transducer array 1, the coverage area is wide and the curvature of the common wavefront 4 is strong. Accordingly, the surface area of ​​the common wavefront 4 grows rapidly with distance, and the sound pressure level therefore decreases rapidly.

[0068] The further away the virtual sound source 12 is positioned from the WFS transducer array 1, the narrower the radiation angle and the smaller the curvature of the spherical section. At very great distances, a nearly parallel wavefront results, the level of which hardly decreases with distance. However, this narrows the coverage area 10 to such an extent that only a portion of the audience area 5 is supplied. The position of the virtual sound source 12 is therefore a compromise between a wide coverage area and an acceptable sound pressure drop in the rear rows of the audience area 3 to be sounded. As shown in the Fig. 1 As is also clear, the same number of transducers in the transducer array 1 serves a significantly larger portion of the audience area 3 to be sounded with distance, and the sound pressure drops significantly there. Furthermore, it is clear that even surfaces outside the audience area 3 to be sounded are unintentionally impacted by the common wave front 4 throughout the entire coverage area 10.

[0069] It is known that a given audience area can be supplied with sound by several virtual sound sources that have the same signal content. A method for this is described in WO 2015 / 022579 A3. A three-dimensional further development of the method is described in patent application DE 10 2019 208 631 A1. The combination of several wavefronts emanating from different virtual sound sources allows for a very balanced sound level across large audience areas 3. Reflecting surfaces can be deliberately omitted, and the level can be adjusted separately for each individual wavefront. Even in reverberant environments, a high direct sound level with correspondingly good speech intelligibility can be achieved throughout the entire audience area 3.The methods come close to the goal of completely and very uniformly irradiating a given audience area 3 with a two-dimensional sound transducer arrangement 1 according to the principle of wave field synthesis.

[0070] However, due to the different positions of the virtual sound sources, these methods result in a time offset between the individual beams (e.g. sound radiation in a certain solid angle range). This leads to comb filter effects in the frequency response in the boundary region of the beams if the time differences between them are not compensated for. Such temporal compensation is possible because the individual virtual sound sources can be controlled independently of one another. In the boundary regions of the individual beams, however, the offset can only be fully compensated for at one point; at other points, perceptible comb filter effects in the upper playback frequency range are unavoidable if wavefronts with coherent signal content overlap in the transition regions.

[0071] The audience area 3 at the venue is essentially predetermined; in practice, its shape and size can hardly be adapted to the acoustic requirements for high-quality sound reinforcement. The area to be served is rarely a flat rectangle. Often, the area is asymmetrical and rises more sharply in the rear areas to ensure a clear view of the stage. The position of the two-dimensional sound transducer array 1, which can operate according to the principle of wave field synthesis, is also essentially predetermined because the sound source must be located in the stage area.

[0072] Therefore, one task is to generate a closed wavefront without transitions between individual beams using an essentially two-dimensional sound transducer arrangement 1, as is known from wave field systems, which is designed in its shape in the azimuth and elevation planes to ensure a uniform distribution of the sound pressure level across the given audience area 3. This can be achieved if the solid angle Ω of the share of a given number of sound transducers in the wavefront to be generated is adjusted for a given part of the audience area 3 so that it each supplies an equally large part of the audience area 3. The solution to the problem is not possible with discrete virtual sound sources of wave field synthesis.

[0073] Embodiments of methods are described below with reference to the figures Fig. 2 bis 9 explained.

[0074] Fig. 2 shows a sound transducer array 1 with a plurality of transducers. The sound transducer array 1 is used to provide sound to an audience area 3. During operation, the individual transducers 9 of the sound transducer array 1 each emit elementary waves 8, which overlap to form a common wavefront 4.

[0075] The transducers 9 of the transducer arrangement 1 are provided with individual delay times τ j operated, ie the sound transducers 9 emit elementary waves 8 at individual delay times. By operating the sound transducer arrangement 1 with the individual delay times τ j the common wavefront 4 is formed. In particular, the common wavefront 4 can be formed by operating with individual delay times τ j be shaped to fit the geometry of audience area 3.

[0076] The sound transducer arrangement 1 and the audience area 3 are assigned to a common coordinate system 2, in which the positions of the individual sound transducers of the sound transducer arrangement 1 are represented by position vectors s i The exact delay times of the individual transducers can be determined by interpolation from the calculated delay times of the surrounding crossing points of the auxiliary grid if the transducers are not exactly at the origin of a position vector s i are arranged.

[0077] The position vectors s i assigned transducer is connected to the individual delay time τ j driven to emit elementary waves 8. In principle, the individual delay times differ τ j the transducers 9 among themselves, but they can also at least partially agree.

[0078] Determining the delay times τ j is carried out by means of an assignment which assigns to each intersection point of the auxiliary grid 5 a crossing point of an auxiliary grid 6 in the audience area 3. In particular, this assignment assigns the sound transducer 9 with position vector s i a point in the audience area 3 corresponding to a position vector r i to.

[0079] The assignment results in the direction vectors 7, which point from the intersection points of the auxiliary grid 5 in the direction of the assigned intersection points of the auxiliary grid 6 in the audience area 3. The normalized direction vectors in the cuboid 60, starting from the position vectors s i are each regulated by the regulation d ^ i = r i − s i r i − s i certainly.

[0080] The assigned position vectors s i determined delay times τ j of the transducer are then selected so that the local direction 50 of the common wavefront 4 at the position vector r i the direction of the normalized direction vector 61 d̂ i corresponds.

[0081] According to the proposed solution, the normalized direction vectors 61 determine the shape of the common wavefront 4. In particular, local directions 50 of the common wavefront 4 can be determined by the direction vectors 7. The normalized direction vectors 61 are each perpendicular to the common wavefront 4.

[0082] By choosing the appropriate allocation (see Fig. 6 ) - and thus the normalized direction vectors 61 - the common wavefront 4 can be shaped to adapt to the geometry of the audience area 3. This is done by assigning the grid points.

[0083] The wavefront 4 is then shaped such that approximately the same number of transducers of the transducer array 1 are assigned to equally sized sub-areas 106 of the audience area 3. The corresponding sub-areas 105 of the wavefront 4 then have different sizes at the same time. The upper sub-area in the diagram is still significantly smaller than the lower one at this distance. Accordingly, the sound pressure within the same wavefront in this area is significantly higher than in the lower sub-area intended for the nearby audience seats.

[0084] Fig. 3 shows a reference surface 30 S, which models the sound transducer arrangement 1 in a coordinate system 2. On the reference surface 30 SA regular, curved auxiliary grid 5 is arranged on the sound transducer arrangement 1, to which the positions of the individual sound transducers 9 of the sound transducer arrangement 1 are aligned. Using the reference surface 30S, in particular using the auxiliary grid 5, coordinates for the individual sound transducers 9 of the sound transducer arrangement 1 can be determined in 3D space.

[0085] The reference area 30 S is parameterized by a system of curved coordinates using the equation s ( u , v ) = [x(u, v) y(u, v) z ( u, v )], where u and v are real variables.

[0086] A normal 202 n on the reference surface 101 S at s ( u , v ) is by definition a normal to the plane formed by the tangent vectors 201 s u and s v , spanned tangent plane, given by the partial derivatives of s(u, v), where s u = ∂ s ∂ u = ∂ x ∂ u ∂ y ∂ u ∂ z ∂ u s v = ∂ s ∂ v = ∂ x ∂ v ∂ y ∂ v ∂ z ∂ v

[0087] The Normal 31 n on s(u, v) is given by the cross product of s u and s v as n = s u × s v .

[0088] The transducers 9 of the transducer array 1 themselves do not need to be mounted at the intersection points of the auxiliary grid 5; their respective delay and level are interpolated to the intersection points in three-dimensional space. The curvature of the reference surface 30S, as well as of the auxiliary grid 5, can be different in the azimuth plane than in the elevation plane; it is also possible to curvature the auxiliary grid 5 only in one plane.

[0089] In practice, the reference area 30 S The sound transducer array 1 is usually a flat surface, and thus the auxiliary grid 5 is a flat auxiliary grid. This corresponds to the case where the sound transducers 9 are mounted essentially in a two-dimensional arrangement. A flat surface is considered a special case of a curved surface.

[0090] Fig. 4 shows the assignment of the auxiliary grid 5 of a sound transducer arrangement 1 to an auxiliary grid 6 in the audience area 3. The solution approach presented here is not based on the position of a virtual sound source (as in Fig. 1 shown), but rather from the given geometry of the audience area 3 to be sound-covered and the geometry of the sound transducer arrangement 1.

[0091] In principle, the audience area 3 to be sound-treated can be of any shape, flat, curved or even rising. Fig. 4 an irregularly shaped audience area 3 to be sounded is shown, which is in particular not symmetrical and rises more sharply in the rear area on the right than on the left side.

[0092] Using conventional approaches, but also using virtual sound sources of wave field synthesis, the task is to create an audience area such as the one in Fig. 4 The problem of supplying the system with direct sound in a very uniform manner, as shown, can only be solved inadequately because the curvature of the wave fronts of virtual sound sources of wave field synthesis is always a section of a sphere.

[0093] However, with the help of the illustrated assignment of the auxiliary grids 5 and 6, a common wave front 4 can be generated, the shape of which is adapted to the geometry of the audience area 3 to be sound-covered.

[0094] To solve the problem, a coordinate system 2 is determined.

[0095] Coordinate system 2 is assigned to coordinate points distributed over the audience area 3. In Fig. 4 These coordinate points are arranged in the audience area 3 at the intersection points of an auxiliary grid 6, but they can also be distributed in the audience area 3 using other mapping methods.

[0096] In addition, the coordinate system 2 is assigned an auxiliary grid 5, by which the positions of the sound transducers 9 of the sound transducer arrangement 1 can be determined. The auxiliary grid is in Fig. 3 represented as a flat, regular auxiliary grid. In principle, however, the auxiliary grid can also be curved, i.e., have curved lines. In principle, the auxiliary grid 5 can be arranged on a reference surface by which the sound transducer arrangement 1 is modeled.

[0097] The number of coordinate points in audience area 3 corresponds to the number of intersection points of auxiliary grid 6. Thus, each intersection point of auxiliary grid 5 can be assigned a coordinate point of auxiliary grid 6 in audience area 3. The distribution of the coordinate points should be carried out across the entire audience area 3 with the distances between the individual coordinate points as uniform as possible.

[0098] Each intersection point of grid 5 is assigned a coordinate point with the position r ( x, y, z ) in the audience area 3. The connecting line 7 between the intersection points of the auxiliary grid 5 and its assigned coordinate point in the audience area 3 then forms a vector in the coordinate system 2, which is the basis for calculating the running time and level of the audio signal.

[0099] The illustrated flat auxiliary grid 5 of the transducer arrangement 1 is rectangular in shape, with an aspect ratio equal to that of the planned transducer arrangement 1, for example, in the form of a transducer array. It should have at least as many intersection points as the number of transducers 9 provided in the transducer arrangement 1. In principle, the aspect ratio is not defined, so it would also be possible to construct a single line of transducers if this is appropriate for the given spatial situation in the audience area 3.

[0100] The spacing of the grid lines of the auxiliary grid 5 may be different in the horizontal and vertical planes, but should at least correspond to the number of rows and columns of the two-dimensional sound transducer arrangement 1.

[0101] The transducers 9 of the transducer array 1 can be mounted with their acoustic center at the intersection points of the auxiliary grid 5. However, their position can also deviate from these intersection points, with their respective propagation times and levels being determined by interpolation of the values ​​calculated for the surrounding grid points.

[0102] A higher number of grid lines improves the accuracy of interpolation. A lower number of grid lines results in a wavefront composed of flat surfaces rather than a uniformly curved one. The resulting diffraction effects lead to local irregularities in the frequency response.

[0103] In principle, physical transducers 9 do not need to be assigned to all intersection points of the auxiliary grid 5. This allows for interrupted placement in the areas where the woofer-midrange transducers 9 have their sound outlets. Furthermore, all transducers 9 can be distributed slightly irregularly across the area, as described in DE 10 2009 006 762 A1. This reduces unwanted aliasing effects in the audience area 3 because the resulting comb filter effects are statistically somewhat balanced in the frequency response.

[0104] The auxiliary grid 6 placed over the audience area 3 completely encloses it. The shape of the auxiliary grid 6 is adjusted to the audience area 3. In principle, this can be done manually. In practice, however, several hundred to several thousand grid points are necessary to ensure that the distance between the transducers 9 is sufficiently small to achieve a reproduction largely free of audible aliasing effects. The small number of grid lines in the sketches serves to provide clarity in explaining the functional principle.

[0105] It is therefore advantageous to automatically determine the coordinate points in the audience area 3 using a 3D CAD file of the audience area 3 and a suitable mapping process. In this way, areas that should not be directly hit by the common wavefront 4 because they emit unwanted reflections can remain free of assigned grid points. This means that no sound transducers 9 are assigned to them whose wavefronts are directed directly in their direction. The coordinate points are shifted from these areas without changing their number. Surrounding coordinate points are shifted accordingly in order to maintain an even distribution across the audience area 3. Each intersection point of the auxiliary grid 5 in the plane of the two-dimensional sound transducer arrangement 1 should be assigned a reference point in the audience area 3 to be sound-covered.

[0106] A visualization in a 3D CAD file facilitates the shutdown of unoccupied audience areas 3. The calculations remain essentially unchanged; only the transducers assigned to unoccupied audience areas 3 are not supplied with a signal. This results in a lower diffuse-field sound level at the venue, which contributes to better speech intelligibility in the occupied audience areas 3.

[0107] Fig. 5 illustrates by way of example how the local curvature 50 of the wavefront 4, which according to the described method does not have to be a spherical section, arises from the superposition of the elementary waves 8 of the surrounding sound transducers 9. For simplification, the acoustic centers of the sound transducers 9 are mounted on the intersection points of the auxiliary grid in the example.

[0108] The individual transducer 9, shown in black in the sketch, has a non-directional half-space radiation according to the principle of wave field synthesis. The elementary wave 8 generated by it alone cannot therefore form a directional vector. The local directional vector d of the wavefront associated with it only arises at some distance from the transducer array 1 through the superposition of the elementary waves 8 of the surrounding transducers.

[0109] The direction vector 7 d is determined for this crossing point using the rule d = r − s determinable. It is always orthogonal to the local wavefront 50.

[0110] In the exemplary illustration in Fig. 5 lies the vector r described point on an intersection point of the auxiliary grid 6 of the audience area 3.

[0111] In principle, the direction vector 7 d can also be determined without the aid of the auxiliary grid 5 and 6. In this case, the direction vector 7 d starts from a position vector s on a reference surface 30 S, which models the sound transducer arrangement 1, and points to a position vector r in the audience area 3, or to a position vector r, which describes a point on a reference surface R 30 modelling the audience area 3.

[0112] The following describes a method for deriving delay times and levels for the individual sound transducers 9 from given direction vectors 7 so that the superposition of their elementary waves 8 superposes to form a wave front that is consistently directed towards the given audience area 3.

[0113] In Fig. 6 is the exemplary selected direction vector 7 d out of Fig. 4 to the length of the normalized direction vector 61 d̂ which is considered d ^ = d d is defined.

[0114] The desired wavefront generated by the sound transducer arrangement 1, in particular in the form of a curved or planar array, can be locally approximated by a plane wave propagating along (i.e. locally in the direction of) the normalized direction vector 61 d̂ propagates. Each local plane wave can be directed in the desired direction by operating the transducers 9 of the transducer array 1 according to the corresponding delay times of the signal.

[0115] The delay time τ j at any position s ( u , v ) on the reference surface 30 S of the transducer arrangement 1 is determined by the scalar-valued delay function τ ( u, v ) described.

[0116] In vector calculus, the gradient of a scalar-valued function τ of several variables a vector field ∇ τ, whose components are given by partial derivatives of τ are determinable, in particular ∇ τ u v = ∂ τ ∂ u ∂ τ ∂ v

[0117] The deceleration gradient can ∇ τc ( u, v ) can be determined in the following way: The scalar products of the normalized direction vector 61 d̂ and tangent vectors s u and s v or d̂ u and d̂ v are given by d ^ u = d ^ ⋅ s u d ^ v = d ^ ⋅ s v

[0118] The scalars d̂ u and d̂ v can be physically interpreted as the local differentials of the path lengths between the plane wave and the tangential plane of the transducer arrangement 1.

[0119] In the special case of a planar transducer arrangement 1, as shown in Fig. 6 shown are d̂ u and d̂ v equal to those in Fig. 6 illustrated sizes d̂ x and d̂ z , which are the x- and z-components of the vector d̂ represent.

[0120] The relationship between the delay gradient ∇ t ( u, v ) from equation (5) and the components d̂ u and d̂ v is given by the speed of sound c. Therefore, the partial derivatives of the delay function τ be described as ∂ τ ∂ u = d ^ u c and ∂ τ ∂ v = d ^ v c .

[0121] In practice, the distance between the transducers 9 is finite. Therefore, the differential equations in equations (7a) and (7b) must be rewritten as discrete difference equations. The delay differences Δ u τ and Δ v τ in u- respectively v-direction are now given by Δ u τ = d ^ u c Δ u and Δ v τ = d ^ v c Δ v , where Δ u and Δ v the discrete step sizes in u-or in the v-direction. The required delay can be determined by numerical integration of the discrete 2D vector field [Δ u τ Δ v τ ] can be found.

[0122] Several mathematical integration methods are available, such as the composite trapezium, Simpson's method, or more advanced inverse gradient methods. The integration constant can be freely chosen. To satisfy the causality condition and minimize system latency, the minimum delay across all drivers is subtracted from the calculated delays.

[0123] The relative gain factor d̂ n for each position in the sound transducer arrangement 1 is given by the scalar product of normalized direction vector 61 d̂ and normal n according to the equation d ^ n = d ^ ⋅ n , where the normal n is defined as in equation (2).

[0124] By operating the transducers 9 according to the relative amplification factors d̂ n ensures that the sound pressure level at the receiver position r is independent of the angle of the direction vector d to the normal n.

[0125] With increasing slope of the radiation relative to the normal n, the number of transducers 9 in a given solid angle Ω increases, so that the sound pressure level would increase here.

[0126] The compensation according to equation (9) corrects this according to a cosine function of the angle γ in Fig. 4 . With a uniform distribution of the coordinate points r, a very homogeneous distribution of the sound pressure over the entire audience area 3 to be sounded is guaranteed.

[0127] In Fig. 7 It is shown that the audience area 3 to be sound-protected can also be divided into individual sub-areas 701, 702, 703 with different signal content.

[0128] In principle, these sub-areas could then also be assigned to sub-areas of the transducer array 1. However, a significantly more precise sound reinforcement is achieved if the high directivity of the entire array is utilized to direct the signal content to the desired audience areas 3. In each of the sub-areas 701, 702, 703, the number of intersection points 6 then corresponds to the number of intersection points 5 of the auxiliary grid of the transducer array 1.

[0129] With identical signal content, dividing the signal into sub-ranges is not useful if the sub-ranges are not sufficiently spatially separated. With coherent signal content, comb filter effects would occur at the range boundaries.

[0130] Individual sub-areas can also be smaller than the assigned sound transducer 9 area, provided that the intersection points of the auxiliary grid in the audience area 3 are closer together than in the auxiliary grid of the sound transducer arrangement 1. In this case, concave wave fronts are created, the sound pressure level of which is higher in the audience area 3 than at the generating radiator surface itself.

[0131] It is also possible to reduce the size of an auxiliary grid in the audience area 3 to a single point. Then, the two-dimensional sound transducer array 1, using the vector-based method described above, generates the same concave wavefront as would be generated in a two-dimensional sound transducer array 1 based on the principle of wave field synthesis for a virtual sound source at this point.

[0132] Using the coordinates of the grid points 5 on the reference surface of the transducer array 1 and their associated coordinates 6 in the audience area 3, it is also possible to compensate for the sound pressure drop at higher frequencies through airborne sound insulation. For a given humidity, the frequency-dependent attenuation values ​​of the air per meter are precisely known. A corresponding inverse equalization curve can then be assigned to each transducer 9, because the distance to the corresponding audience seat (given by the length of the direction vector d in Fig. 5 ) is known.

[0133] In large audience areas 3, the sound pressure drop at the upper limit of the audio range can exceed ten dB in dry air. In any case, this frequency range must be addressed at a significantly higher level in a planar transducer array 1, because the gain in level due to the improved matching of the synchronously operating loudspeaker array only takes effect at longer wavelengths. The additional compensation of the airborne sound insulation for the distant audience areas 3 can therefore push the system to the limits of its controllability at high signal levels in the upper audio frequency range.

[0134] One solution to this problem is to use the coordinate points r to be arranged closer to one another with increasing distance from the transducer array 1. The far-flung audience areas 3 are then assigned a smaller partial area 106 for the same number of transducers 9. Each halving of the area results in a level increase of 3 dB, by which the control of the assigned transducers 9 would have to be reduced so that the sound pressure level in the entire audience area 3 remains virtually constant. The correspondingly reduced control signal is associated with greater headroom in the assigned amplifiers. This can then be used to further equalize the control signals.

[0135] The localization of the sound source in the described method differs fundamentally from the localization of a virtual point sound source in wave field synthesis. In wave field synthesis, virtual sound sources are located at their virtual point of origin, similar to a real sound source, regardless of the listener's position in the coverage area.

[0136] However, the wavefront tailored to audience area 3 does not originate from defined positions of virtual sound sources. It arises from an extended source of many different starting points in the area behind the transducer surface. The spectator in the front left seat in Fig. 2 will assign the starting point of the wave front in the lower left corner of the transducer arrangement 1, for the viewer in the back right the sound comes from the upper right corner of the transducer arrangement 1. This is not a disadvantage for the reproduction without optical reference to the sound source, a spatial reproduction is according to the Figur 2 but only possible to a limited extent.

[0137] Nevertheless, the method can be assigned to the field of wave field synthesis because the theoretical derivation of wave field synthesis from the Kirchhoff-Helmholtz integral makes it possible to generate any desired shape of the wave front (Jens Ahrens: The Single-layer Potential Approach Applied to Sound Field Synthesis Including Gases of Non-enclosing Distributions of Secondary Sources, Dissertation, Technical University of Berlin, 2010). Weitere Ausgestaltungen

[0138] So far, it has been assumed that the transducers 9 of the transducer array 1 are arranged in a regular grid. In practice, however, the distribution of the transducers 9 can also be irregular. First, the propagation times τ calculated to a sufficiently dense regular grid, after which the travel times to the irregularly placed sound transducers are interpolated.

[0139] Fig. 8 shows a complexly designed audience area 3 with sub-areas 802 and illustrates an assembly of the sound transducer arrangement 1 with sound transducers 9, wherein the assembly is adapted to the complex design of the audience area 3.

[0140] In the illustrated embodiment, the assignment between points on the sound transducer arrangement 1 and points in the audience area 3 is carried out by assigning intersection points of the auxiliary grid 5 of the sound transducer arrangement 1 to intersection points of the auxiliary grid 6 of the audience area 3.

[0141] However, not all intersection points of the auxiliary grid 5 are assigned to sound transducers 9 of the sound transducer arrangement 1; in other words, intersection points of the auxiliary grid 5 remain unpopulated. In particular, unpopulated intersection points are found between populated intersection points.

[0142] In fixed installations, the shape of the transducer array 1 can be adapted to the complex design and / or geometry of the audience area 3. This enables more effective use of the transducers.

[0143] The auxiliary grid 6 in the audience area 3 can, for example, be a rectangle; in particular, it can extend beyond the audience area.

[0144] Irregular shapes of the auxiliary grid 6 may lead to incorrect results in the calculations according to the described procedure.

[0145] Intersecting points of the auxiliary grid 6 in the audience area 3, to which no audience is assigned, ie which in the present case lies outside the partial areas 5a, 5b, 5c of the audience area 3 to be sound-covered, are assigned auxiliary grid points of the auxiliary grid 5 of the sound transducer area, which are not equipped with sound transducers or are switched off.

[0146] Any woofer-midrange transducers used are also aligned to the auxiliary grid 5 of the transducer array 1. Their travel times and levels are calculated based on the nearby grid points. The time shift resulting from any bass offset must be compensated for. The phase position of subwoofers can also be effectively adjusted in this way. According to the procedure, the shortest of all calculated travel times to the individual transducers is subtracted from all calculated travel times, so that the wave front adapted to the audience area 3 is always generated directly.

[0147] A further refinement of the solution involves a device shaped according to the rules of the described method. This device can generate a single wavefront, whose shape is adapted to the given audience area, from a mono signal without electronic time shifting of the signal. This mechanical solution can be advantageous for fixed installations in acoustically challenging environments. Thus, a sound reinforcement system can be installed with reasonable effort that ensures a high direct sound component with correspondingly good speech intelligibility, even under unfavorable acoustic conditions.

[0148] In Fig. 9 a mechanically curved sound transducer arrangement 1 is illustrated as an example.

[0149] By means of the mechanically curved sound transducer arrangement 90, the sound wave described with reference to Fig. 4 described audience area 3 to be sounded is supplied with a tailored common wave front 4.

[0150] The operation of the sound transducers 9 of the sound transducer arrangement 1 is controlled according to the delay times obtained by the described method τ j Mechanically implemented. All transducers are supplied with a coherent signal, i.e., from a mono signal source.

[0151] The mechanical realization is achieved by suitable positioning of the sound transducers 9 on the mechanically curved sound transducer arrangement 90, in particular by a suitable spatial offset, in particular an offset in the propagation direction of the common wavefront, of the sound transducers 9 to one another.

[0152] In order to determine the respective position of the transducers 9 in the adapted transducer area for the audience area 3 to be sounded, a distance S d , starting from the corresponding grid point of a plane auxiliary grid 5 along the extended diagonal of the unit vector 61 d̂ certain cuboid 40 removed.

[0153] Using the known alternating angles α and β In the right-angled triangles of the cuboid 40, the new coordinates for the acoustic center of the respective sound transducer 9 and also its orientation can be determined.

[0154] The delay times calculated according to the described methods for the individual transducers 9 are caused by the mechanical offset of the acoustic centers of the respective transducers 9 along the diagonal S d of the respective cuboids.

[0155] The different signal levels for the individual sound transducers 9 of this two-dimensional sound transducer arrangement 1 can then be approximately realized at a common power amplifier by suitable parallel and series connection of the sound transducers 9 or by connection to different amplifiers, each of which is assigned to sound transducers 9 with approximately the same level values.

[0156] As long as the sound transducers 9 do not have significant dips in their spatial radiation characteristics, they do not need to be aligned in the direction of the diagonals of the cuboid. In this case, the method can also be implemented using a device for transverse displacement of sound transducers, as described in WO 2015 / 004526 / A2. The displacement s y of the acoustic center from the grid point of the original transducer grid is then determined from the quotient S d cos γ .

[0157] A single mechanical device cannot create a spatial sound reinforcement of the audience area 3. It is suitable for ensuring, with manageable effort, a sound reinforcement in which the distribution of the sound pressure level is very uniform throughout the entire audience area 3 and which ensures high speech intelligibility even in acoustically unfavorable rooms.

[0158] In the following, some embodiments of methods and devices for providing sound to a given audience area 3 by means of a sound transducer arrangement 1, which is controlled with individual delay times and levels based on the principle of wave field synthesis, are presented.

[0159] For example, in a variant 1 of a method, the shape of the acoustic common wavefront 4, which is composed by superposition of elementary waves 8 of the sound transducers 9, can be determined from the given geometry of the audience area 3 and the sound transducer arrangement 1 in such a way that, in a common coordinate system 2, each intersection point of a regular, at least partially flat and / or curved grid assigned to the sound transducers is assigned a coordinate point in the audience area 3, whereby a vector results from their connecting line, from which the delay time for the respectively assigned sound transducer 9 can be calculated by mathematical combination, whereby the local curvature of the wavefront, which arises by superposition of the elementary waves 8 of the surrounding sound transducers 9, progresses in the direction of this vector, so that a closed wavefront is created,which can reach the entire audience area 3 and in which a level correction for each sound transducer 9 from its assigned vector is possible, which improves the homogeneity of the sound pressure over the entire audience area 3.

[0160] In one embodiment of variant 1, for example, the coordinate points in the plane of the two-dimensional sound transducer arrangement 1 are intersection points of a flat or curved grid, to which coordinate points in the audience area 3 are assigned in a common coordinate system 2, wherein the connecting lines between the respectively assigned grid points and points in the audience area 3 do not cross or intersect.

[0161] In a further embodiment, the number of grid lines in the plane of the two-dimensional sound transducer array 1 in the horizontal and vertical directions corresponds to the number of sound transducers installed in the rows and columns of the two-dimensional sound transducer array 1. Alternatively, the number of grid lines can be greater than the number of sound transducers 9 in the rows and columns of the two-dimensional sound transducer array 1, whereby the acoustic center of the individual sound transducers 9 can be arranged at the intersection point of the grid lines. The values ​​for delay time and / or level can be determined, for example, by interpolating the values ​​of the surrounding grid points.that the reference points in the audience area 3 can be adapted in all three spatial dimensions to the requirements of the geometry of the audience area 3, whereby care must be taken to ensure that the areas between the individual grid points remain approximately the same size over the entire audience area 3, resulting in a relatively uniform distribution of the sound pressure level over the entire audience area 3.

[0162] In a further embodiment of variant 1 or one of the above variants, the vectors resulting from the difference between the coordinates of the grid point assigned to the respective sound transducer 9 in the plane of the two-dimensional sound transducer arrangement 1 and the respective position of the assigned coordinate point in the audience area 3 are mapped to components of the unit vector d̂ to create a mathematical basis for determining the time differences between neighboring transducers.

[0163] In principle, not all intersection points of the auxiliary grid need to be assigned physical transducers 9 that radiate the same frequency range. This makes it possible, for example, to interrupt the configuration in the areas where the woofer-midrange transducers 9 have their sound outlets or to place tweeters in front of the woofer-midrange transducers, with the time lag differences caused by the mechanical offset being compensated for by interpolation at the intersection points of the auxiliary grid.

[0164] In a further embodiment of the variants described above, the influence of the angle that the synthesized wavefront takes at a given grid point to the plane of the sound transducer arrangement 1 on the signal level perceived at the associated point in the audience area 3 is compensated by compensating the level of the sound transducer associated with the respective point with the cosine function of the angle in question, the value of this cosine function corresponding to the value of the component d ^ n of the unit vector d̂ corresponds.

[0165] In principle, several auxiliary grids in the audience area, each with the same number of points as the grid in the plane of the two-dimensional sound transducer arrangement 1, can also be assigned to the intersection points of the flat or curved grid in the plane of the two-dimensional sound transducer arrangement 1, whereby sub-areas within the audience area can, for example, be supplied simultaneously with different signal content.

[0166] The reference points in the audience area 3 can be distributed more closely with increasing distance from the two-dimensional sound transducer arrangement 1, for example with the intention of making the areas between the reference points smaller with the distance from the two-dimensional sound transducer arrangement 1, so that the associated sound transducers 9 of the two-dimensional sound transducer arrangement 1 can be controlled with a lower level while the sound pressure in the respective area remains unchanged, whereby more headroom is available for compensating the treble drop due to the airborne sound insulation in these areas.

[0167] The influence of airborne sound insulation on the signal at the audience seat for the individual sound transducers 9 can be compensated by equalizing their respective input signal with the inverse equalization of the influence of airborne sound insulation at a given air humidity according to the distance || d|| of the associated vector can be compensated.

[0168] In principle, individual audience areas 3 can be temporarily excluded from the sound system. For example, if they are not occupied during an event, this improves the direct sound component in the remaining audience areas 3.

[0169] In a device for providing sound to a given audience area 3, the propagation times with which the individual sound transducers 9 of the two-dimensional sound transducer arrangement 1 radiate according to one of the method variants described above are not realized by electronic delay of the signal content, but by the mechanical positioning of the sound transducers, which are controlled with coherent signals, wherein the signal levels for the respective sound transducer 9 correspond to the values ​​determined for the original crossing points of the grid.

[0170] The following describes additional embodiments and aspects of the invention that may be used individually or in combination with any of the features, functionality, and details described herein.

[0171] A first aspect relates to a method for providing sound to at least one audience area (3) by means of at least one sound transducer arrangement (1) with a plurality of sound transducers (9), wherein the individual sound transducers (9) of the at least one sound transducer arrangement (1) each emit elementary waves (8) which are superimposed to form a common wave front (4), dadurch gekennzeichnet, that a) the at least one sound transducer arrangement (1) and the at least one audience area (3) are geometrically linked to one another by a coordinate system (2) and b) between the physical positions of the individual sound transducers (9) in the at least one sound transducer arrangement (1) and position vectors s i for determining coordinates in the area of ​​the at least one sound transducer arrangement (1) there is a spatial assignment, and further c) an assignment of points of the coordinate system (2) to points in the at least one audience area (5) according to a position vector r i where d) in the coordinate system (2) there are direction vectors, in particular normalized direction vectors (61) d ^ i = r i − s i r i − s i and where e) depending on the spatial assignment of the position vectors s i and the transducer (9) delay times τ j for the sound transducers (1) are determined, with which elementary waves (8) are radiated by the sound transducers (9), where e) the delay times τ j the sound transducer (9) is selected in such a way that the local direction (50) of the common wavefront (4) corresponds to the direction of the direction vector, in particular the normalized direction vector (61) d̂ i corresponds.

[0172] According to a second aspect with reference to the first aspect, the method dadurch gekennzeichnet, dass the sound transducers (9) of the at least one sound transducer arrangement (1) are arranged in or on a plane or in or on an at least partially curved or planar surface (30), in particular in a grid-like manner, wherein the position of the acoustic centers of the sound transducers can deviate from the intersection points of the auxiliary grid (5) insofar as the associated change in delay time and level is corrected by spatial interpolation or other methods.

[0173] According to a third aspect with reference to the first aspect, the method dadurch gekennzeichnet, dass the sound transducers (9) of the at least one sound transducer arrangement (1) are arranged in a three-dimensional area, in particular a space, in particular such that at least a subset of the sound transducers (9) of the at least one sound transducer arrangement (1) is arranged on a reference surface (30) and the positions of the remaining sound transducers (9) of the at least one sound transducer arrangement (1) can be determined by an offset (91) in the three-dimensional area.

[0174] According to a fourth aspect with reference to the first to third aspects, the method dadurch gekennzeichnet, dass the operation of the transducers (9) with delay time τ j by means of a computer system and / or mechanically, in particular by spatial offset (91) of the sound transducers (9) of the at least one sound transducer arrangement (1) relative to one another.

[0175] According to a fifth aspect with reference to the first to fourth aspects, the method dadurch gekennzeichnet, dass the at least one audience area (3) has at least partially a concave and / or at least partially a convex shape.

[0176] According to a sixth aspect with reference to the first to fifth aspects, the method dadurch gekennzeichnet, dass the at least one public area (3) can be described as a continuous area.

[0177] According to a seventh aspect with reference to the first to sixth aspects, the method dadurch gekennzeichnet, dass the at least one public area (3) can be described as a discontinuous area which is composed of at least two connected areas.

[0178] According to an eighth aspect with reference to the first to seventh aspects, the method dadurch gekennzeichnet, dass the position vectors s i create a regular grid.

[0179] According to a ninth aspect with reference to the first to eighth aspects, the method characterized in that the position vectors r i a regular grid (6) on an area assigned to at least one public area (3).

[0180] According to a tenth aspect with reference to the first to ninth aspects, the method characterized in that the assignment that each position vector si the point in at least one audience area (3) corresponding to the position vector r i assigns, can be determined by means of connecting lines from the at least one sound transducer arrangement (1) into the audience area (3).

[0181] According to an eleventh aspect with reference to the first to tenth aspects, the method characterized in thatthe levels at which the sound transducers (9) of the at least one sound transducer arrangement (1) are operated are adjusted so that the sound pressure in at least one audience area (3) is homogeneous.

[0182] According to a twelfth aspect with reference to the eleventh aspect, the method characterized in that the levels at which the sound transducers (9) of the at least one sound transducer arrangement (1) are operated can be determined by means of a relative amplification factor, based on the rule d̂n = d̂ i - ni where no the normal to the reference surface (30) S at the position vector s i which is assigned to the sound transducer (9).

[0183] According to a thirteenth aspect with reference to the first to twelfth aspects, the method characterized by the fact that the at least one audience area (3) has at least two sub-areas which are provided with different signal content.

[0184] According to a fourteenth aspect with reference to the first to thirteenth aspects, the method characterized by that the common wavefront (4) is shaped such that it is adapted to the geometry of the at least one audience area (3) by assigning the grid points and then shaping the common wavefront (4) such that substantially the same number of sound transducers (9) of the sound transducer arrangement (1) is assigned to equally sized sub-areas (106) of the at least one audience area (3).

[0185] According to a fifteenth aspect with reference to the first to fourteenth aspects, the method characterized bythat sub-areas of the at least one audience area (3) are assigned sub-areas of the sound transducer arrangement (1), to which a different audio content can be assigned simultaneously, wherein a directivity of the sound transducer device (1) is used to align signal contents to predetermined parts of the at least one audience area (3), wherein in each of the sub-areas (701, 702, 703) the number of crossing points (6) then corresponds to the number of crossing points (5) of the auxiliary grid of the sound transducer arrangement (1).

[0186] A sixteenth aspect relates to a method for determining delay times τ j for operating sound transducers (9) of at least one sound transducer arrangement (1) with a plurality of sound transducers (9) j for generating elementary waves (8) according to the delay times τ j for sound reinforcement of at least one audience area (3), comprising the following steps Determination of a coordinate system (2) by which ∘ the at least one sound transducer arrangement (1) is approximately represented as a two-dimensional reference surface (30) S the at least one sound transducer arrangement (1) and ∘ the at least one audience area (3) are approximately described, determination of position vectors s on the reference surface (30) S the at least one sound transducer arrangement (1), from which the positions of the sound transducers (9) of the at least one sound transducer arrangement (1) can be determined, determining an assignment which is assigned to each position vector s on the reference surface (30) S the at least one sound transducer arrangement (1) a position vector r corresponding to a point in at least one audience area (3), determining direction vectors, in particular standardized direction vectors (61) d starting from the position vectors s, where the normalized direction vectors (61) d starting from the position vectors s in the direction of the position vector assigned to the position vector s r shows; and determination of delay times τ j for sound transducer j, so that the elementary waves (8) generated by the sound transducers (9) during operation according to the delay times τ j to form a common wavefront (4), whereby the normalized direction vectors (61) d each describe local propagation directions (50) of the common wavefront (4).

[0187] According to a seventeenth aspect with reference to the sixteenth aspect, the method comprises determining relative gain factors d̂n for at least a subset of the position vectors s according to the rule d ^ n = d ^ ⋅ n , where n is a normal to the reference surface (30) S the sound transducer arrangement (1) is at the point determined by the position vector s and d the normalized direction vector (61) starting from the position vector s.

[0188] According to an eighteenth aspect with reference to the sixteenth or seventeenth aspect, the method characterized in that the position vectors s describe the positions of the sound transducers (9).

[0189] According to a nineteenth aspect with reference to the sixteenth to eighteenth aspects, the method characterized in that each position vector s on the reference surface (30) S the at least one sound transducer arrangement (1) a position vector r on a reference surface R of the at least one public area (3) and the determination of the direction vector, in particular the standardized direction vector (61) d for at least one position vector s by means of a connecting line (7) between the position vector s and the position vector r, in particular according to the calculation rule d ^ = r − s r − s

[0190] According to a twentieth aspect with reference to the nineteenth aspect, the method characterized in that the connecting lines (7) for determining the normalized direction vectors (61) d Do not cross or cut in pairs.

[0191] According to a twenty-first aspect with reference to the sixteenth to twentieth aspects, the method characterized in that the assignment between the position vector s and the position vector r is carried out automatically, in particular using a 3D CAD file of the at least one audience area (3).

[0192] According to a twenty-second aspect with reference to the sixteenth to twenty-first aspects, the method characterized in that the position vectors r are evenly distributed on the reference surface R of the at least one audience area (3) and thereby correspond to evenly distributed points in the at least one audience area (3).

[0193] According to a twenty-third aspect with reference to the sixteenth to twenty-second aspects, the method characterized in that the reference area R of the at least one public area (3) is described by an auxiliary grid (6) on which the position vectors r are at least partially intersection points.

[0194] According to a twenty-fourth aspect with reference to the sixteenth to twenty-third aspects, the method characterized in that the reference surface (30) S the at least one sound transducer arrangement (1) is described by an auxiliary grid (5) on which the position vectors s are at least partially crossing points.

[0195] According to a twenty-fifth aspect with reference to the sixteenth to twenty-fourth aspects, the method characterized in that the reference surface (30) S the at least one sound transducer arrangement (1) by means of the coordinates s(u,v) = [x(u, v) y(u, v) z(u, v)]is parameterized, where u and v are real, continuous variables or discrete variables and thus in particular the position vectors in the form s = s(u, v) are writable.

[0196] According to a twenty-sixth aspect with reference to the sixteenth to twenty-fifth aspects, the method characterized in that the normal n to the reference surface (30) S the sound transducer arrangement (1) at the point defined by the s = s(u, v) described point is given by the cross product of s u and sv as n = s u × s v , where s u and s v are given by the partial derivatives s u = ∂ s ∂ u = ∂ x ∂ u ∂ y ∂ u ∂ z ∂ u or s v = ∂ s ∂ v = ∂ x ∂ v ∂ y ∂ v ∂ z ∂ v .

[0197] According to a twenty-seventh aspect with reference to the twenty-sixth aspect, the method characterized in that to determine the respective delay times τ jfirst a scalar-valued function of delay times τ ( u, v ) for a finite set of position vectors of the form s = s ( u, v ) and the determination of the delay times τ j for the transducers (9) with position vector s i at least partly by interpolation of at least two values ​​of the form τ ( u, v ) takes place.

[0198] According to a twenty-eighth aspect with reference to the twenty-seventh aspect, the method characterized in that the scalar-valued function of delay times τ ( u, v ) by numerical integration of the discrete 2D vector field [Δ u τ Δ v τ ] is determined, where the delay differences Δ u τ in u-direction or Δ v τ in v- Direction is given by Δ u τ = d ^ u c Δ u or Δ v τ = d ^ v c Δ v , where Δ u and Δ vdescribe discrete step sizes in the u-direction and v-direction, respectively, where c describes the speed of sound and where d̂ u and d̂v by the scalar products d ^ u = d ^ ⋅ s u or d ^ v = d ^ ⋅ s v are given, where d the normalized direction vector (61) starting from the position vector s = s ( u , v ) describes and s u and s v Tangent vectors to the reference surface (30) S starting from the position vector s = s ( u , v ), in particular where s u and s v are given by the partial derivatives s u = ∂ s ∂ u = ∂ x ∂ u ∂ y ∂ u ∂ z ∂ u or s v = ∂ s ∂ v = ∂ x ∂ v ∂ y ∂ v ∂ z ∂ v .

[0199] According to a twenty-ninth aspect with reference to the twenty-seventh or twenty-eighth aspect, the method characterized in thatthe numerical integration method includes the composite trapezium method, the Simpson method, the Romberg method or the more advanced inverse gradient method.

[0200] A thirtieth aspect relates to a computer program product for determining delay times τ j for operating sound transducers (2) i at least one sound transducer arrangement (1) with a plurality of sound transducers (2) i for generating elementary waves (3) according to the delay times τ i for sound reinforcement of at least one audience area (5) characterized in that the computer program product comprises means for executing at least one instruction for determining delay times τ j for sound transducer j according to at least one of claims 1 to 15 or 16 to 29.

[0201] A thirty-first aspect relates to a device for providing sound to at least one audience area (3), which device comprises at least one sound transducer arrangement (1) with a plurality of sound transducers (9), wherein the at least one sound transducer arrangement (1) is operable according to a method according to at least one of claims 1 to 15.

[0202] According to a thirty-second aspect with reference to the thirty-first aspect, the at least one sound transducer arrangement (1) and the at least one audience area (3) are geometrically linked to one another by a coordinate system (2) and a distinction is made between the physical positions of the individual sound transducers (9) in the at least one sound transducer arrangement (1) and position vectors si for determining coordinates in the area of ​​the at least one sound transducer arrangement (1) there is a spatial assignment, and furthermore an assignment of points of the coordinate system (2) to points in the at least one audience area (5) according to a position vector r i wherein in the coordinate system (2) direction vectors, in particular normalized direction vectors (61) d ^ i = r i − s i r i − s i result, characterized by a means for controlling the sound radiation of the sound transducers (9), which depends on the spatial assignment of the position vectors si to the transducers (9) delay times τ j for the sound transducers (1), with which elementary waves (8) are radiated by the sound transducers (9), wherein the delay times τ jthe sound transducer (9) is selected in such a way that the local direction (50) of the common wavefront (4) corresponds to the direction of the direction vector, in particular the normalized direction vector (61) d̂ i and means for assigning each sound transducer (9) to a point in the at least one audience area (3) according to a position vector r i , so that normalized direction vectors (61) d ^ i = r i − s i r i − s i and a means of determining the delay time τ j the sound transducer (9) so that the local direction (50) of a common wavefront (4) corresponds to the direction of the normalized direction vector (61) d̂ i corresponds, wherein in particular the individual sound transducers (9) of the at least one sound transducer arrangement (1) each emit elementary waves (8) which are superimposed to form a common wave front (4) and the at least one sound transducer arrangement (1) and the at least one audience area (3) are assigned to a common coordinate system (2) in which the positions of the individual sound transducers (9) of the at least one sound transducer arrangement (1) and the sound transducers are each determined with a delay time τ j operable to emit elementary waves (8).

[0203] According to a thirty-third aspect with reference to the thirty-first or thirty-second aspect, the device characterized bythat the different propagation times for the sound transducers (9) of the sound transducer arrangement (1) are realized using a mechanical or geometric positioning of the sound transducers (9) which are controlled with coherent signals, wherein in particular the signal levels for the respective sound transducer (9) can correspond to the values ​​determined for the original crossing points of the grid. Reference symbol

[0204] 1Sound transducer arrangement 2Common coordinate system 3Audience area 4Wavefront formed from elementary waves 5Auxiliary grid on the reference surface of the sound transducer arrangement 6Auxiliary grid in the audience area 7Directional vector 8Elementary waves 9Sound transducer 10Supply area of ​​the wavefront 105Partial areas of the wavefront 106Partial areas of the audience area 12Virtual sound source 30Curved transducer surface 31Normal 40Cuboid for vector determination 50Local direction of the common wavefront 60Normalized cuboid with diagonal one 61Normalized direction vector 701, 702, 703Partial areas of the audience area 801Used intersection points 802Fixed audience areas 90Mechanically curved transducer arrangement 91Spatial offset

Claims

1. A method for providing sound to an audience area using a plurality of sound transducers, the method comprising the steps of: arranging the plurality of sound transducers in a predefined spatial configuration; establishing a coordinate system defining spatial relationships between the plurality of sound transducers and a plurality of target points within the audience area; calculating, for the plurality of sound transducers, a plurality of delay times based on a plurality of distances between the plurality of sound transducers and corresponding target points from the plurality of target points, such that a plurality of elementary waves emitted by the plurality of sound transducers combine to form a common wavefront aligned with a desired propagation direction within the audience area;Determining a plurality of output levels for the plurality of transducers based on the coordinate system and a geometry of the audience area such that a substantially uniform sound pressure level is achieved across the audience area; and outputting the plurality of waveforms from the plurality of transducers with corresponding delay times from the plurality of delay times and a corresponding output level from the plurality of output levels to project the common wavefront into the audience area.

2. The method of claim 1, wherein each acoustic transducer of the plurality of acoustic transducers is associated with a position vector defining its acoustic center in the coordinate system.

3. The method of claim 1 or 2, wherein calculating the plurality of delay times comprises determining the plurality of delay times such that a local direction of the common wavefront corresponds to a normalized direction vector.

4. The method according to any one of the preceding claims, wherein calculating the plurality of delay times comprises correcting the plurality of delay times by spatial interpolation when the acoustic center of a sound transducer deviates from an origin of its position vector.

5. The method of any preceding claim, wherein determining the plurality of output levels comprises applying a plurality of relative gain factors to the plurality of acoustic transducers based on a plurality of angles between the desired propagation direction and a plurality of lines connecting the plurality of acoustic transducers to the plurality of target points.

6. A system for delivering sound to an audience area, the system comprising: a plurality of sound transducers arranged in a predefined spatial configuration; and a signal processor configured to: calculate a plurality of delay times for the plurality of sound transducers based on a plurality of distances between the plurality of sound transducers and corresponding target points from the plurality of target points such that a plurality of wavelets emitted by the plurality of sound transducers combine to form a common wavefront aligned with a desired propagation direction within the audience area;Determining a plurality of output levels for the plurality of transducers based on a coordinate system defining spatial relationships between the plurality of transducers and a plurality of target points within the audience area, and a geometry of the audience area, such that a substantially uniform sound pressure level is achieved across the audience area; and outputting the plurality of waveforms from the plurality of transducers with corresponding delay times and output levels to project the common wavefront into the audience area.

7. The system of claim 6, wherein each of the plurality of transducers is associated with a position vector defining its acoustic center in the coordinate system.

8. The system of claim 6 or 7, wherein the signal processor is further configured to calculate the plurality of delay times such that a local direction of the common wavefront corresponds to a normalized direction vector.

9. The system of any preceding claim, wherein the signal processor is further configured to correct the plurality of delay times by spatial interpolation when the acoustic center of a sound transducer deviates from an origin of its position vector.

10. The system of any preceding claim, wherein the signal processor is further configured to determine the plurality of output levels by applying a plurality of relative gain factors to the plurality of acoustic transducers based on a plurality of angles between the desired propagation direction and a plurality of lines connecting the plurality of acoustic transducers to the plurality of target points.

11. A computer program product comprising program code instructions stored on a non-transitory computer-readable storage medium, the program code instructions configured to cause one or more processors to perform a method for providing sound to an audience area using a plurality of sound transducers arranged in a predefined spatial configuration, the method comprising the steps of: establishing a coordinate system defining spatial relationships between the plurality of sound transducers and a plurality of target points within the audience area;Calculating, for the plurality of transducers, a plurality of delay times based on a plurality of distances between the plurality of transducers and corresponding target points from the plurality of target points, such that a plurality of wavelets emitted by the plurality of transducers combine to form a common wavefront aligned with a desired propagation direction within the audience area; Determining a plurality of output levels for the plurality of transducers based on the coordinate system and a geometry of the audience area, such that a substantially uniform sound pressure level is achieved across the audience area;and outputting the plurality of elementary waves from the plurality of transducers with corresponding delay times from the plurality of delay times and corresponding output levels from the plurality of output levels to project the common wavefront into the audience area; 12. The computer program product of claim 11, wherein each acoustic transducer of the plurality of acoustic transducers is associated with a position vector defining its acoustic center in the coordinate system.

13. The computer program product of claim 11 or 12, wherein calculating the plurality of delay times comprises determining the plurality of delay times such that a local direction of the common wavefront corresponds to a normalized direction vector.

14. The computer program product of any preceding claim, wherein calculating the plurality of delay times comprises correcting the plurality of delay times by spatial interpolation when the acoustic center of a sound transducer deviates from an origin of its position vector.

15. The computer program product of any preceding claim, wherein determining the plurality of output levels comprises applying a plurality of relative gain factors to the plurality of acoustic transducers based on a plurality of angles between the desired propagation direction and a plurality of lines connecting the plurality of acoustic transducers to the plurality of target points.

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