EP4122223A1

EP4122223A1 - Acoustic transducer arrangement and method for operating an acoustic transducer arrangement

Info

Publication number: EP4122223A1
Application number: EP21717765.8A
Authority: EP
Inventors: Michael Hlatky; Philippe Robineau
Original assignee: Holoplot GmbH
Current assignee: Holoplot GmbH
Priority date: 2020-03-20
Filing date: 2021-03-19
Publication date: 2023-01-25
Also published as: US20230135696A1; DE102020203659A1; WO2021186065A1

Abstract

The invention relates to an acoustic transducer arrangement (1) based on the principle of wave field synthesis, characterized in that at least one first acoustic transducer (11) is coupled to an acoustic low pass filter unit (5). The invention relates to a method for operating a two-dimensional acoustic transducer arrangement.

Description

The invention relates to a sound transducer arrangement having the features of claim 1 and a method for operating a sound transducer arrangement having the features of claim 27.

The principle of wave field synthesis is known for the reproduction of audio signals (see e.g. Berkhout, AJ (1988): A holographic approach to acoustic control. Journal of the Audio Engineering Society, Vol. 36, No. 12, December 1988, pp.977- 995.).

According to the Huygens principle, sound wave fronts are reconstructed from a large number of elementary waves. Each elementary wave emanates from the acoustic center of a sound transducer, which is controlled by its assigned amplifier. The superposition of elementary waves is also the basis of the beamforming principles, with which sound waves can be radiated preferentially in a desired direction (see e.g. Schröder, Jaeckel, Evaluation of beamforming Systems, 4th Berlin Beamforming Conference 2012.4th)

In principle, these elementary waves should synthesize the wave fronts in the entire audible transmission range. In order that the sound wave fronts synthesized from the elementary waves can be emitted with the same amplitude in every direction, the functional principle requires an undirected caluman radiation of the individual sound transducers. In order to avoid unwanted interferences in the reproduction area, which manifest themselves in aliasing effects, the individual sound transducers should theoretically be arranged at a distance of less than half a wavelength of the emitted signal - also for the upper transmission range (e.g. more than 4 kFIz).

For the reproduction area, ie an interior and / or exterior area, a source-free volume is required in wave field synthesis, ie all reflections should be avoided. However, because a complete acoustic control of the playback room can hardly be realized in practice, the wave fronts must be aligned both in the azimuth and in the elevation plane. In this way, the occurrence of reflections can largely be avoided in that the reflective surfaces of the reproduction room are not unintentionally hit by the synthesized wavefronts. With horizontal rows of sound transducers around the audience, as implemented, for example, in a system at the TU Berlin

(http://www.fouraudio.com/de/referenz/wellenfeldsvnthese-an-der-tu-berlin.htmn, this is not possible. In the elevation plane there are arranged cylindrical waves.

From WO 2015/036845 A1 it is known to build larger, two-dimensional sound transducer surfaces in modules based on the principle of wave field synthesis. With a two-dimensional sound transducer arrangement (e.g. DE 2005 10001395 A2) based on the principle of wave field synthesis, however, the requirement for aliasing-free reproduction in the entire transmission range leads to a disproportionately high effort, because the total number of sound transducers quadruples when their distance from one another is reduced. In practice, such radiator surfaces are built up in such a way that a largely closed wave front can be generated up to the range of speech reproduction, i.e. up to around 4 kFIz. The audio frequencies above are of less importance for the localization of the sound source, so that direction-dependent aliasing effects are permitted here.

Dynamic loudspeakers are common as sound transducers. However, with the corresponding diaphragm diameter, their natural resonances are several octaves above the lower limit frequency of the audio range to be reproduced, which is required for high-quality reproduction. The sensitivity and resilience of dynamic loudspeakers are also far below the values that are standard for larger sound transducers.

In such a two-dimensional arrangement, the efficiency of the individual sound transducers improves as the wavelength of the signal increases, because they work increasingly synchronously as the frequency decreases. The upstream air can therefore no longer evade the membrane movement unhindered in all directions, which is why a larger air mass is now upstream of the membrane. Compared to a single sound transducer, the load of the column of air to be moved results in a significantly improved adaptation to the radiation resistance of the air, because the membrane is no longer almost empty works, but finds a work resistance. This leads to a significant increase in level towards lower frequencies. However, it cannot compensate for the driver's steeper sound pressure drop below its natural resonance. That is why the use of different sound converters with the appropriate division of the frequency ranges to be emitted is an advantageous solution.

Such a division of the reproduction range into individual frequency ranges leads to only minor irregularities in the vertical directional characteristic of the system in the horizontal WFS sound transducer rows, for example in the Flörsaal TU Berlin (see Anselm Goertz, Michael Makatsch, Christoph Moldrzyk, Stefan Weinzierl: Zur Entzerrung von Loudspeaker signals for wave field synthesis (Equalization of loudspeaker signals for wave field synthesis systems), 25th TONMEISTERTAGUNG - VDT INTERNATIONAL CONVENTION, November 2008).

Complex challenges arise in a flat or spatial arrangement of sound transducers based on the principle of wave field synthesis. The assembly of the various sound transducers is not possible in one plane because the wave front has to be reconstructed in all three spatial dimensions without major gaps in the distance between the high-frequency transducers. Therefore the acoustic centers of the elementary waves, from which the wave front to be synthesized is composed, do not lie in a common plane.

1 shows a schematic sectional view of a sound transducer arrangement. Here, three first sound transducers 11 are shown, which are designed here as conical sound transducers by way of example. A plurality of second sound transducers 12 is arranged between the first sound transducers 11. In the embodiment shown, these are designed as spherical transducers, which are often used for the high-frequency range. As is known from coaxial loudspeakers, the second sound transducers 12 can also be arranged in the area of the diaphragm of the sound transducers 11, provided that they do not hinder its sound exit. The arrangement of several tweeters in front of the diaphragm of woofer is known in principle.

B. Elementary waves 311, 312 each emanate from the first sound transducers 11 and the second sound transducers 12 and have their point of origin in the acoustic centers 211, 212 of the first sound transducers 11 and second sound transducers 12.

In the case of calotte sound transducers, such as the second sound transducers 12 shown here, the acoustic centers 212 are approximately on the front side of the dome. In the case of cone sound transducers, such as the first sound transducers 11 shown here, the acoustic centers 211 of the elementary waves 311 are in the rear part of the cone, slightly in front of the front of the dust protection cap (Sven Franz, Christina Imbery, Menno Müller, Jörg Bitzer: “Determination of the frequency-dependent acoustic center of a loudspeaker in the time domain "; Institute for Flörtechnik und Audiologie Oldenburg). The exact position depends on the frequency. With regard to the superposition of the elementary waves from the first and second sound transducers 11, 12, the position of the acoustic centers in the transition area of their working frequencies is decisive.

As can be seen from FIG. 1, the arrangement and construction of the first and second sound transducers 11, 12 result in a geometric offset of the associated acoustic centers. In particular, the acoustic centers of the first and second sound transducers 11, 12 do not lie on one plane. With regard to the main propagation direction of the respective sound transducers 11, 12, the first sound transducers 11 are located behind the second sound transducers 12.

This geometric offset cannot simply be compensated for over time in the case of wave field synthesis and it also leads to problems with the superposition of the elementary waves in the beamforming process. In the illustration of FIG. 1, it becomes clear that elementary waves 311 of the first conical sound transducer 11 offset to the rear can be adapted in terms of time so that a common front line 4 is formed with the elementary waves 312 of the second dome sound transducer 12. Then, however, the radius of the elementary waves 311 of the cone sound transducers 311 is greater than the radius of the elementary waves 312 of the dome sound transducers 12. This results in an inhomogeneous distribution of the wave fronts.

The superposition of inhomogeneous wavefronts inevitably leads to direction-dependent irregularities in the frequency response, especially in the crossover area unwanted side loops. Such side loops should, however, be avoided as far as possible if the control of the playback area is to be dispensed with. They could generate unwanted reflections, which would counteract the freedom from source of the playback room, which is inherent in wave field synthesis. Such reflections are easy to localize especially in the mid-range, in which the crossover frequency is usually located, which is why they would permanently falsify the spatial reproduction.

The object is to improve the radiation characteristics of a sound transducer arrangement; in particular, it should be possible to compensate for a geometric offset of sound transducers in a sound transducer arrangement.

This object is achieved by an object with the features of claim 1.

In this case, at least one first sound transducer in the sound transducer arrangement is coupled to an acoustic low-pass filter device.

For example, the acoustic center of the first sound transducer can be arranged behind the acoustic centers of the high-frequency transducers in relation to the front of the sound transducer arrangement.

The acoustic center of the first sound transducer and the low-pass filter device can, for example, in one embodiment be shifted into a plane with the acoustic centers of Flochton sound transducers as second sound transducers. This makes it possible to ensure a homogeneous superposition of elementary waves even in the transition area of the transmission frequencies, although the chassis of the sound transducers themselves are mounted in different planes. In such a "loudspeaker system", the sound waves no longer emanate from the loudspeaker itself. It only builds up air pressure in the chamber, not a wave. The sound wave is created at the exit of the air duct from the oscillating column of air.

An acoustic low-pass filter device uses the spring action of a volume of air in series with the mass of air (1,293 g / 1) in a duct. The volume can then be the chamber volume plus the volume of the membrane cone. Air can only come out of the duct, so the acoustic center is then at the outlet of this duct. The acoustic low pass causes, among other things, a 90 degree phase shift at the outlet of the air duct, which is taken into account when driving high-frequency loudspeakers.

The at least one acoustic low-pass filter device can be placed in front of, i.e. in particular in the main direction of propagation of the elementary wave that can be generated by the at least one first sound transducer. The filter device can, however, also assume other positions relative to the coupled sound transducer, e.g. be offset or positioned laterally. However, in one embodiment, the outlet of the air duct with its oscillating air mass, which as the acoustic center is the starting point of the elementary wave of the at least one first sound transducer together with a loudspeaker chassis and the acoustic low-pass, end in the plane of the acoustic centers of the sound transducers.

The acoustic low-pass filter device can be or comprise a mechanical device. As such, it can have a resilient volume of air in an air chamber. The air chamber can be located in front of the coupled sound transducer.

A cavity, in particular the volume of the membrane cone, of the coupled sound transducer can also be part of the air chamber of the acoustic low-pass filter device and / or part of the sound transducer can be part of the boundary of the air chamber. In particular, a cone of the sound transducer can be part of the air chamber or make it up entirely. The cone can, however, also have an air-conducting connection with a further air chamber to the air chamber of the acoustic low-pass filter device. A conical volume of the at least one first sound transducer can be part of the resilient air volume or correspond to it. The acoustic low-pass filter device can have a neck or a comparable constriction of the air outlet which comprises an oscillating air mass.

The neck of the acoustic low-pass filter device does not have to be designed as a tube. Rather, it can deviate from a straight line and one in approximately circular or polygonal cross-section or any shape. A straight tube can also have a cross section that deviates from a circular cross section.

The opening of the neck into the surroundings can be integrated in a plate in front of the respective at least one first sound transducer; an opening in such a plate can also be designed as an opening of the neck into the surroundings or can be designed as the neck itself.

It should be noted that part of the upstream air is relatively rigidly connected to the air in the duct and must therefore be added to the oscillating mass. The corresponding calculation bases for this are known from the orifice correction for bass reflex tubes.

The at least one first sound transducer can be designed as a mid-range sound transducer, as a low-mid-range sound transducer and / or a low-frequency sound transducer. It can be a dynamic loudspeaker, in particular a cone sound transducer, but can also be implemented using a different transducer principle.

A plurality of first sound transducers can be arranged in a pattern in one embodiment. This pattern can in particular be a one-, two- or three-dimensional grid pattern in which the first sound transducers are arranged regularly or almost regularly (e.g. a slight offset due to aliasing is possible). The grid pattern does not necessarily have to be arranged in one plane, so that grid arrangements in a surface with curvatures are also conceivable. For example, sound transducers of a similar construction type or a similar transmission range (e.g. mid-range, low-mid range, or low-range sound transducers) can assume an analogous position.

Further sound transducers of the sound transducer arrangement can be arranged relative to one another in a second pattern, in particular a grid pattern. Further sound transducers can, for example, tweeter sound transducers, in particular dome Be a transducer. These further sound transducers also do not necessarily have to be arranged in a planar pattern.

The first and second patterns can be superimposed to form a common pattern or represent an overlay of two grid patterns. In one embodiment, the second sound transducers can also be mounted in the oscillating air mass, in which case their influence on the limit frequency of the acoustic low-pass must be taken into account.

The at least one acoustic low-pass filter device can be designed as a Helmholtz resonator or have a Helmholtz resonator. A Helmholtz resonator has an air volume of any shape that is connected to the environment via a comparatively small-volume neck. The air in the throat can be seen as an inert mass. The entire volume of air forms an elastic volume, so that there is a spring-mass system. Such a spring-mass system can, for example, be coupled to a sound transducer by placing it in front of the sound transducer. The Helmholtz resonator thus serves as a low-pass filter device.

In a further embodiment, the acoustic low-pass device can be designed so that the numerical value of the ratio of the area of the outlet opening to the product of the volume of its air chamber and the length of its neck ^ is between 100 and 5000, the area and the volume in square or cubic meters , and the length of the neck is given in meters.

If a plurality of first sound transducers of the sound transducer arrangement are coupled to acoustic low-pass filter devices, the acoustic centers of the first sound transducers with coupled low-pass filter devices can lie on a surface, in particular a plane.

Furthermore, the acoustic center of the at least one first sound transducer with a coupled low-pass filter device and a second sound transducer of the sound transducer arrangement can lie on a surface, in particular a two-dimensional plane. The area can in particular be spanned by the acoustic centers of the first and second sound transducers - using the low-pass filter device. Accordingly, the acoustic centers of the first sound transducers and acoustic low-pass filter devices coupled therewith and the acoustic centers of second sound transducers of the sound transducer arrangement can be arranged in one area, in particular one plane.

The acoustic center of the at least one first sound transducer can be positioned by means of the coupled acoustic low-pass filter device, in particular it can be displaced along the direction of sound propagation. This can be used to set the spatial radiation characteristic of the sound transducer arrangement, in particular for a homogeneous structure of the elementary waves of wave field synthesis or a related beamforming method.

The direction of displacement of the first acoustic center of the at least one first sound transducer can be collinear to the direction of propagation of an elementary wave generated by the at least one first sound transducer. The direction of propagation of the elementary wave is determined by the vector, which is perpendicular to the plane that delimits the space in which the transducer emits.

In particular, the acoustic center of the at least one first sound transducer can be shifted by means of the coupled acoustic low-pass filter device in such a way that it is on the level of a second sound transducer that the shifted acoustic center is on the level of the fleas of the acoustic center of a second sound transducer, the level of the Fleas of the acoustic center of a sound transducer is described by the plane which runs through the acoustic center of the sound transducer and is perpendicular to the vector of the direction of propagation of the elementary waves generated by the sound transducer.

Conversely, the acoustic center of the first sound transducer can also be shifted by means of the coupled acoustic low-pass filter device in such a way that the acoustic center of a second sound transducer lies on the level of the fleas of the shifted acoustic center. In a further embodiment, the additional phase rotation of a signal of the at least one first sound transducer, which is created by coupling with an acoustic low-pass filter device, can be compensated for by adapting the control, in particular by delaying the control of the at least one second sound transducer, so that the elementary waves of the Superimpose sound transducers in the sound transducer arrangement to form a common wavefront.

In one embodiment, the cutoff frequency of the at least one acoustic low-pass filter device can be tuned above, in particular one to two octaves above, a crossover frequency of a transmission range of the respective at least one first sound transducer. Accordingly, the transmission range of the at least one first sound transducer does not have to be significantly changed by coupling to one of the acoustic low-pass filter devices.

Furthermore, second sound transducers can be aligned differently, especially for the flochtone area, deviating from the main axis of the sound transducer arrangement, which is perpendicular to the two-dimensional sound transducer surface, with the aim of enhancing the reproduction for distant listeners who are far away from the main axis in the direction of emission of the sound transducer. Arrangement are located to linearize. The main axis of the transducer arrangement can relate to a local area in the case of curved surfaces.

The described embodiments also relate to a modular sound transducer system which comprises, for example, at least two sound transducer arrangements which are arranged such that the radiating surfaces of the respective sound transducer arrangements are arranged in one plane, are part of a curved surface or approximate a curved surface. The described embodiments relate to a module in the modular sound transducer system or to the modular sound transducer system as a whole.

A module in a sound transducer system can in particular be designed as a three-way module or have such a module. This can be the first transducer that is available as a Conical transducers are designed and can be used for the transmission of the medium frequency spectrum. These are each coupled to an acoustic low-pass filter device.

Furthermore, the module can have dome sound transducers that can be used for audio transmission of the upper frequency spectrum. These can be mounted in groups on circuit boards in such a way that their distance from one another is less than the distance between the midrange speakers. In particular, in such a way that their distance from one another is less than the shortest wavelength of the frequency range to be transmitted without perceptible aliasing effects. At the upper limit of the transmission range, there are wavelengths of approx. 2.15 cm. In practice, a distance of 4-12 cm, in particular 8 cm, between Flochton transducers is usually sufficient to ensure transmission without noticeable aliasing effects.

Furthermore, the module can have at least one bass sound transducer, which is arranged behind the flochtone sound transducers and mid-tone sound transducers, and the sound pressure of which can be implemented as a double-ventilated bandpass.

In the following, the context and embodiments are explained with reference to the drawings. These show:

1 shows a sectional view of a sound transducer arrangement according to the prior art;

2 shows a schematic sectional view of a sound transducer arrangement in which first sound transducers are each coupled to an acoustic low-pass filter device;

3 shows a sectional view of a sound transducer arrangement in which first sound transducers are each coupled to an acoustic low-pass filter device and the elementary waves generated by the first and second sound transducers are superimposed to form a common, homogeneous wave front; 4 shows a first sound transducer of a sound transducer arrangement, which is coupled to an acoustic low-pass filter device;

5 schematically shows a grid pattern in which the first and second sound transducers of a sound transducer arrangement are arranged relative to one another;

6 shows a sectional view of a sound transducer arrangement in which the first sound transducers are each coupled to an acoustic low-pass filter device, resulting in a homogeneous wave front.

7 shows a sectional view of a sound transducer arrangement in which first sound transducers are each coupled to an acoustic low-pass filter device and with second sound transducers with adapted alignment;

8 shows a perspective illustration of an exemplary embodiment of a sound transducer module;

9 shows a perspective illustration of an embodiment of a modular sound transducer system;

10 shows a further embodiment of a sound transducer arrangement.

FIG. 2 schematically shows a sectional view of a sound transducer arrangement 1 or a sound transducer module 7 (as shown by way of example in FIG. 8). These and all of the following embodiments show embodiments for sound transducer arrangements and methods for operating sound transducer arrangements.

First sound transducers 11 are shown, with each of which an acoustic low-pass filter device 5 is coupled. The detail shows four first sound transducers 11, but the number is only to be understood as an example.

The acoustic low-pass filter device 5 is shown here in each case directly in front of the first sound transducers 11, ie in particular in the positive propagation direction 3111 of the elementary wave 311 generated by the respective first sound transducers 11. This positioning is only to be understood as an example; a different, for example offset or lateral positioning of the acoustic low-pass filter device 5 with reference to the coupled first sound transducer 11 is also possible.

The first sound transducers 11 shown in FIG. 2 are arranged equidistantly on a straight line. In further embodiments, first sound transducers 11 of an area of a sound transducer arrangement 1, a sound transducer module 7 or even the entire sound transducer arrangement 1 are arranged relative to one another in a first pattern 611, in particular a grid pattern. This pattern can be a one-, two-, or three-dimensional pattern, in particular also such a grid pattern (see e.g. Fig. 5).

Furthermore, FIG. 2 shows second sound transducers 12, the positions of which alternate with those of the first sound transducers 11 along the straight line. This special arrangement is also only provided as an example. The second sound transducers 12 could be arranged in a second pattern 612, in particular a grid pattern. Further sound transducers of the sound transducer arrangement shown in extracts could also be arranged in a second pattern. In one embodiment, first pattern 611 and second pattern 612 can be superimposed to form a common pattern 6, as is shown by way of example in FIG. 5.

Second sound transducers 12, to which reference is made below, can be second sound transducers 12 of the sectional view shown, but also second sound transducers 12 on a different position of the sound transducer arrangement 1 shown in detail in FIG Have spatial proximity in the sound transducer arrangement to the first sound transducers 11.

The elementary waves 311 generated by the first sound transducer 11 have their apparent origin in an acoustic center 211, which is shown by way of example in FIG. 2 as a point. The acoustic center 211 of a first sound transducer 11 can be determined, for example, by the design of the first sound transducer 11. This is how the acoustic center of a cone sound transducer lies for example in the rear part of the cone, roughly at the front of the dust protection cap.

The acoustic centers 211 of the first sound transducers 11 can be positioned by means of the coupled acoustic low-pass filter device 5, in particular along an axis. This is explained by way of example with reference to FIGS. 3 and 4. The location of the displaced acoustic center 211 can be regulated and determined, for example, by the type or construction of the acoustic low-pass filter device 5 and / or by the placement of the acoustic low-pass filter device 5 in relation to the coupled first sound transducer 11.

In particular, the acoustic center 211 of a first sound transducer 11 can be shifted collinearly to the direction of propagation 3111 of the elementary wave 311 generated by the first sound transducer 11 by means of the coupled acoustic low-pass filter device 5.

By coupling to the acoustic low-pass filter device 5, the acoustic center 211 of the first sound transducers 11 can be positioned such that the radii of curvature of the elementary waves 312, 311 generated by coupled first sound transducers 11 and second sound transducers 12 are adapted or correspond and thus the generation a homogeneous wave front 4 through the transducer arrangement 1 or the transducer module 7 is made possible.

For example, the acoustic centers 212 of second sound transducers 12 and the acoustic centers 211 of first sound transducers 11 with coupled acoustic low-pass filter device 5 can be positioned on a common surface, in particular on a convex or concave plane.

The acoustic center 211 of a first sound transducer 11 can be shifted by means of the coupled acoustic low-pass filter device 5 such that the shifted acoustic center 211 lies on the plane of the fleas of the acoustic center 212 of a second sound transducer 12, the plane of the fleas of the acoustic center of a sound transducer is described by the plane that runs through the acoustic center of the sound transducer and perpendicular to the Vector of the direction of propagation of the elementary waves generated by the sound transducer.

The cut-off frequency of an acoustic low-pass filter device 5 determines the frequency range that is attenuated by the filter device; specifically, the sound above the cut-off frequency is attenuated and below the cut-off frequency it is passed through almost unhindered.

In one embodiment, the cutoff frequency of the acoustic low-pass filter device 5 is tuned above the operating range or above, in particular one to two octaves above, the crossover frequency of a transmission range of the first sound transducer 11 coupled to the acoustic low-pass filter device 5.

The cut-off frequency can in particular be tuned in such a way that the reproduction frequency range of the first sound transducer 11 is not significantly changed by coupling to an acoustic low-pass filter device 5; in particular, the acoustic low-pass filter device 5 has no undesirable audible effect on the transmission range of the coupled first sound transducer 11.

If the cut-off frequency of the acoustic low-pass filter 5 is close to the upper limit of the transmission range of the respective first sound transducer 11 for the lower transmission range, harmonics of the first sound transducer 11 cannot reach the audience, whereby the distortion factor of the first sound transducer 11 can be reduced.

The first sound transducers 11 can be, for example, mid-range sound transducers, low-mid-range sound transducers and / or low-frequency sound transducers. These can be implemented, for example, as dynamic loudspeakers, in particular as cone sound transducers, as shown in FIGS. 3 and 4. The second sound transducers 12 can be Flochton sound transducers which are implemented as dome sound transducers (FIG. 3). The acoustic low-pass filter devices 5 can in particular have resonators (ie an air system made up of a mass and a resilient air volume), as is shown in FIGS. 3 and 4. FIG. 3 shows a sectional view of a sound transducer arrangement 1 or a sound transducer module 7, which as a special embodiment of the object of FIG.

2 is to be understood. In particular, descriptions of FIG. 2 can also be found on FIG.

3 transferred. FIG. 3 is also to be understood as an embodiment applied to the object of FIG. 1.

The first sound transducers 11 are shown in FIG. 3 by way of example as cone loudspeakers which are usually used for the mid-tone to low-frequency range.

An acoustic low-pass filter device 5 is coupled to each of the first sound transducers 11. This is placed directly in front of the first sound transducers 11 in FIG. 3 and is shown as a mechanical device, which is described in more detail with reference to FIG. 4.

The illustrated mechanical acoustic low-pass filter device 5 each have a resilient air volume 53 in an air chamber 51. In the embodiment shown by way of example in FIG. 3, the air chamber 51 consists of the cone 511 of the cone sound transducer 11 and a further air chamber 512. The resilient air volume 53 therefore consists of the cone volume 531 and possibly another air volume 532. The air chamber 51 could, however, also correspond to the cone 511 or comprise or contain another air chamber of the first sound transducer 11. A part, in particular a wall, of the first sound transducer 11 could be part of the delimitation of the air chamber 51. The air chamber 51 could, however, also be built independently of the first sound transducer 11; in particular, the air chamber 51 could not have any boundaries in common with the first sound transducer 11.

In the embodiment shown in FIG. 3, the air chambers 51 of the acoustic low-pass filter devices 5 are partially delimited by a plate 55 which is attached in front of the first sound transducers 11.

The embodiment of the acoustic low-pass filter device shown in FIG. 3 furthermore has a neck 52 which comprises an oscillating volume of air 54. In FIG. 3, the necks 52 of the three acoustic low-pass filter devices 5 are aligned such that their openings 521 into the surroundings lie in one plane. In the form shown, openings 551 in the plate 55, which partially delimit the air chambers 51, are part of the delimitation of the necks 52. This construction is only to be understood as an example.

By coupling with the acoustic low-pass filter devices 5, the acoustic center of the first sound transducer 11 is shifted approximately at the level of the openings in the necks 52. A comparison of the acoustic centers 211 of the first sound transducers 11 in FIG. 1 with the acoustic centers 211 of the first sound transducers

11 with the coupled acoustic low-pass filter device 5 in FIG. 3 shows that the acoustic centers of the first sound transducers 11 have been shifted as a result of the coupling with the acoustic low-pass filter devices 5. In particular, the acoustic centers have been shifted along the directions of propagation of the elementary waves 311 generated by the respective first sound transducers 11. The displaced acoustic centers 211 of the first sound transducers 11 lie on a surface.

FIG. 3 also shows second sound transducers 12, which are shown by way of example as dome sound transducers which are usually used for the high-frequency range. The calotte sound transducers are here, for example, attached to the plate 55, which represents the delimitation of the air chambers 51 of the acoustic low-pass filter device 5. The plate can also be the carrier board of the second sound transducer.

The first sound transducers 11 and second sound transducers 12 are arranged in a common grid pattern 6; in particular, in the arrangement shown in FIG. 3, a first sound transducer 11 is followed by three second sound transducers

12 in a repetitive manner. This arrangement is only to be understood as an example. The second sound transducers 12 can also be mounted in the area of the opening of the air duct if their influence on the oscillating air mass is taken into account when dimensioning the acoustic low-pass filter. In the embodiment shown in FIG. 3, the openings 521 of the necks 52 of the acoustic low-pass filter devices 5 and the domes 721 of the dome sound transducers lie approximately on one surface. Since the displaced acoustic centers (displaced by the acoustic low-pass filter devices 5) are approximately at the level of the opening of the necks 52 and the acoustic centers 212 of the dome sound transducers are on their domes 721, the acoustic centers 211 of the first sound transducers 11 are also located coupled low-pass filter devices 5 and the acoustic centers 212 of the second sound transducer 12 in approximately one area.

In particular, by coupling with the acoustic low-pass filter devices 5, the acoustic centers 211 of the first sound transducers 11 have been shifted to the plane in which the second sound transducers 12 have their acoustic centers 212.

The radii of curvature of the elementary waves 311, 312 of the first sound transducers 11 and the second sound transducers 12 are adjusted to one another by the displacement of the acoustic centers, which is shown by a comparison with the radii of curvature of the elementary waves 311, 312 in FIG.

As part of a coupling with an acoustic low-pass filter device 5, a phase shift of the signals from the first sound transducer 11 is brought about. This additional phase shift of the signal from the first sound transducers 11 can be compensated for by an adapted control of the second sound transducers 12, in particular by a delay in the control of the second sound transducers 12, so that the elementary waves 311, 312 overlap to form a common, homogeneous, synthesized wavefront 4. This is illustrated by a comparison of the wavefront in FIG. 3 with the wavefront in FIG. 1.

4 shows a single first sound transducer 11 from a sound transducer arrangement 1, which is coupled to an acoustic low-pass filter device 5. The first sound transducer 11 is shown here as an example of a cone sound transducer.

An acoustic low-pass filter device 5 is coupled to the first sound transducer 11. In the mechanical embodiment, this is an acoustic one Low-pass filter device is shown, which is placed immediately in front of the first sound transducer 11.

In the acoustic low-pass filter device 5, a resilient air volume 53 is coupled to an oscillating air volume 54; the former corresponds to a feather. The resilient 53 and the oscillating air volume 54 form a mass-spring system. The resilient air volume 53 is encompassed by an air chamber 51 and the oscillating air volume 52 is encompassed by a short neck 52. This corresponds to a Helmholtz resonator.

In FIG. 4, the air chamber 51, which comprises the resilient air volume 53, consists of the cone 511 of the cone sound transducer 11 and a further air chamber 512. The resilient air volume 53 thus consists of the cone volume 531 and a further air volume 532.

Part of the delimitation of the neck 52 of the acoustic low-pass filter device 5 shown in Fig. 4 is an opening 551 in a plate 55 in front of the first sound transducer 11, i.e. the opening 551 in a plate 55 is integrated in the neck 52. The opening 551 in the plate 55 could also correspond to the opening 521 of the neck 52 into the surroundings. The opening in the plate 551 could, however, also correspond entirely to the neck 52. However, the neck 52 could also have been formed in a different way.

If several, e.g. all mid-range sound transducers, all low-mid-range sound transducers and / or all low-frequency sound transducers, are coupled in a sound transducer arrangement 1 with an acoustic low-pass filter device 5, a plate 55 in front of the sound transducer arrangement 1 can have several openings 551 which each serve as openings 521 of the necks 52 of the various acoustic low-pass filter devices 5 or are integrated into the necks 52 of the acoustic low-pass filter devices 5.

In the embodiment shown, the neck 52 is designed as a tube, in particular the neck 52 has a circular cross-section. However, it could also have a different cross-section, for example a polygonal cross-section. The opening of the neck but can also have a different shape, which can be determined in particular by the design of the sound transducer arrangement as a whole or results from the design.

The acoustic center of the first sound transducer 11 migrates through coupling with the acoustic low-pass filter device 5 to the end of the flale 52 of the acoustic low-pass filter device 5, in which the oscillating air volume 54 determines the upper limit frequency of the acoustic low-pass filter device 5.

In the example shown in FIG. 4, the acoustic center of the first sound transducer 11 is shifted by means of the coupled acoustic low-pass filter device 5 in the direction of propagation 3111 or the elementary wave 311 generated by the first sound transducer 11.

The calculation of the cut-off frequency of the acoustic low-pass can be done in the same way as the calculation of the resonance frequency of a Flelmholz resonator. The value of the cutoff frequency of the acoustic low-pass filter device should be at least a third to an octave higher than the electrical crossover frequency of an electronic crossover of the corresponding sound transducer.

The resonance frequency is calculated according to the following formula / = where c is the

Speed of sound, S is the cross-section of the opening of the flale, L is the length of the neck and V is the volume of the resilient air mass. In addition, the orifice opening correction must be taken into account, because part of the upstream air must be included in the oscillating mass.

The calculation of the cut-off frequency of this acoustic low-pass filter device can be carried out analogously to the calculation of the resonance frequency of a Helmholtz resonator. This is calculated according to the formula where c is the

Speed of sound in m / s, S the area of the outlet opening of the neck in m ² , L the length of the neck in m and V the volume of the resilient air mass in m ³ . In addition, the orifice opening correction must be taken into account, because part of the upstream air must be included in the oscillating mass. The formula then changes to twice the diameter of the opening of the neck multiplied is added to the length of the neck of the moving air mass. This results in somewhat lower values for the cutoff frequency.

The upper end of the working range of a mid-range transducer is typically between 1 and 4 kHz. With the cutoff frequency of the coupled acoustic low-pass above the transmission range of the mid-range loudspeaker, there is, for example, a ratio of the area of the outlet opening to the product of the volume and length ae of the neck - between 100 and 5000. VL

5 shows schematically a pattern 6 in which sound transducers of a sound transducer arrangement are arranged. A plurality of first sound transducers 11, which are arranged in a first grid pattern 611, and further sound transducers which are arranged in a second grid pattern 612 are shown.

In the form shown, the first grid pattern 611 and the second grid pattern 612 overlap to form a common grid pattern 6.

The first sound transducers 11 can be, for example, mid-range sound transducers, low-mid-range sound transducers and / or low-frequency sound transducers. These could, for example, have been implemented as cone sound transducers. As shown in FIG. 5, the first pattern can be a grid pattern, but other regular arrangements of the sound transducers are also possible. The pattern can also be a one-, two- or three-dimensional pattern. The low-pass filter devices 5, which are coupled to the first sound transducers 11, are only shown here with their mouth opening for reasons of clarity. A second sound transducer 12 can also be mounted inside the mouth opening if its influence is included in the calculation of the low pass. In the first pattern 611, for example, sound transducers of a similar construction type or a similar working area can assume analogous positions.

The further sound transducers can be, for example, high-frequency sound transducers, low-frequency sound transducers and / or mid-tone sound transducers. For example, further sound transducers can be implemented as spherical sound transducers.

In the second pattern 612, further sound transducers of a similar construction type or a similar work area can assume similar or repetitive positions. However, their position can also deviate from the regular grid if the runtimes and levels for your control are interpolated accordingly to the coordinates of the regular grid. As described in DE 10 2009 006 762 A2, aliasing effects in the upper playback frequency range can be reduced in this way.

The first and the second pattern can represent a superposition of two grid patterns or combine to form a common grid pattern. In this grid pattern, sound transducers of a similar type (e.g. cone or dome loudspeakers) or a similar designated transmission range (e.g. high-frequency, mid-range and / or low-frequency transducers) can take up analogue positions.

The invention is to be explained in the following on the basis of a further exemplary embodiment. Other designs, also with a different division of the frequency ranges, are possible.

FIG. 6 shows, similar to the embodiment according to FIG. 3, a sectional view of a sound transducer arrangement 1 or a sound transducer module 7. The descriptions from FIG. 3 can be transferred to the illustration shown here.

In addition, the directional characteristics 3121 of the second sound transducers, which are shown here as spherical sound transducers as in FIG. 3, are shown in FIG. 6. The directions of propagation of the elementary waves generated by the first and second sound transducers run parallel to one another. Tweeter transducers can only emit evenly in all directions if their diaphragm diameter is smaller than the wavelength of the sound to be generated. At 16 kHz this is only 2.15 cm. With such a small membrane area, however, only a small amount of sound pressure can be generated at the lower end of its reproduction range. A compromise must always be found here between uniform spatial radiation, maximum sound pressure and the lower limit frequency of the transmission range. A crossover frequency that is as low as possible to the mid-range transducers enables a greater distance between the individual mid-range transducers, because aliasing effects in the crossover area must be avoided here. This greater distance then also enables larger diaphragm diameters, which then enables more efficient reproduction at the lower end of the reproduction frequency range of the mid-tone transducers.

The radiation characteristic of high-frequency transducers is not constant in all directions; at certain frequencies, significant drops in radiation are unavoidable depending on the direction. This is shown in FIG. 6 by the irregular shape of the directional characteristics 3121. As a matter of principle, these problems increase with the diaphragm diameter. For listeners far from the transducer arrangement, the solid angle of neighboring transducers is almost the same. At the frequencies concerned, this leads to a non-linearity in the frequency response of the reproduction that is dependent on the respective position of the listener in the reproduction area.

This non-linearity cannot be compensated for by equalizing the overall signal, because this would result in an overemphasis on the relevant frequency in other places. With reference to FIG. 7, it is explained how the described effect can be reduced.

FIG. 7 shows a sectional view of a structure comparable to FIG. 6. In contrast to the structure in FIG. 6, the mounting directions of the second sound transducers 12 are changed. In particular, second sound transducers 12, which can be used in the exemplary structure for the high-frequency range, are oriented differently, deviating from the main axis 81 of the system. The aim of this is to linearize the reproduction for distant listeners who are far away from the main axis in the emission direction of the sound transducer arrangement 1.

In the embodiment shown by way of example, the high-tone transducers 12 are not mounted parallel on a plate, but rather at a slight incline, as a result of which the angles of inclination of the high-tone transducers are slightly different and in particular deviate from the main axis 81 of the system.

This randomly distributed, slight deviation in the mounting direction of the high-frequency sound transducers 12 can reduce the effect described with reference to FIG. 6. Although, as in the scenario represented by FIG. 6, the radiation characteristic of high-frequency transducers 12 is not constant in all directions, as shown by the irregular shape of the directional characteristics 3121, not all high-frequency loudspeakers are now aligned in the same way when viewed from a specific audience position. In this way it can be avoided that an extended area of the sound transducer arrangement is mechanically exactly in the direction towards the listener in which the radiation of a certain frequency is significantly reduced.

Fig. 8 shows an example of the structure of the sound transducer module, which is shown here as a three-way module, based on the principle of wave field synthesis

The upper frequency spectrum of the audio transmission range is realized in the exemplary structure with spherical transducers 72. Cone sound converters 71 are used for the middle frequency spectrum and the bass range is designed as a double-ventilated band pass 731, 732.

The dome sound transducers shown in FIG. 8 have a very small overall depth. They are mounted in groups on printed circuit boards, which they connect to the amplifiers on the rear of the modules via connectors. Their distance from one another is selected so that reproduction is largely free of aliasing effects right into the forman area of the vowels. They guarantee in their Working area a half-space radiation without deep breaks in the directional polar pattern. In principle, however, the solution according to the invention is not limited to the use of dynamic sound transducers.

At the upper frequency limit of their working range, the diaphragm diameter of the diaphragm diameter of high-frequency transducers is in the range of the emitted wavelength. Here they are therefore relatively well adapted to the working resistance of the air and the phase position of the signal can differ significantly between neighboring transducers. Therefore, an improvement in the efficiency due to better adaptation compared to each individual sound transducer is not to be expected here.

In contrast, the phase differences between neighboring transducers are small at the lower frequency limit of their working range. The wavelength of the signal is several times larger than its membrane diameter. The advantage here is that the group is better adapted to the load resistance of the transmission medium compared to the individual sound transducer. The efficiency increases significantly compared to that of the same single radiator, and the weight of the air column that now weighs on the dome shifts its natural resonance significantly downwards. The otherwise necessary coupling of the sound transducer about an octave above its natural resonance can be shifted down to the area close to its open-air resonance.

The improved efficiency then contributes to the fact that the sound transducer arrangement 1 can generate higher maximum sound pressure levels than is possible with conventional PA loudspeakers. Because of the distributed arrangement of the transducers, the problem does not arise that the air in front of the small membrane area of a high-frequency transducer has to be compressed into the range of non-linearity in order to still generate the high sound pressure often used at live events in a large audience area. This limits the theoretically possible maximum sound pressure level of conventional loudspeaker systems.

In front of the larger total area of the generating drivers in the flat sound transducer arrangement 1 according to the principle of wave field synthesis, the remains Sound pressure in front of each individual sound transducer is much lower, so that with the appropriate design of the amplifiers and drivers in the audience area, a significantly higher sound pressure can be generated without the non-linearity of the compression curve of the air leading to non-linearities in the perceived audio signal.

In addition, the improved efficiency in the flat sound transducer arrangement 1 significantly facilitates the selection of the sound transducers for the adjacent frequency range. Their distance from one another should in turn be less than the wavelength at the upper limit of their transmission range. This can also be implemented in practice because of the relatively deep coupling of the high-frequency transducers 72.

The diaphragm diameter of the cone loudspeakers used remains below the emitted wavelength in their entire frequency range. At the lower end of the band, the wavelength of the signal is more than a power of ten larger than each individual membrane, so that it would be completely mismatched here if it did not work in the group with the neighboring transducers. In the bass range, the improved adaptation of the group therefore results in a very significant increase in efficiency, comparable to the better adaptation of the drivers in horn loudspeakers.

However, drivers with the diaphragm diameter, which results from their relatively small distance from one another, are not sufficient to generate the extreme sound pressure in the deep bass range, which is now considered to be indispensable in the PA sector. The natural resonance of dynamic loudspeakers with a corresponding diameter is usually well above 100 Hz if they have the high sensitivity required in the PA area. Below the natural resonance, the sound pressure curve falls significantly more steeply than the increase can compensate for through the efficiency of the group.

The two-way modules could be supplemented with external subwoofers as usual. However, an integration of the sub-bass range in a wave field synthesis sound transducer area has significant advantages if a larger number of modules are combined to form a sound transducer area. In addition to better customization, lets With a sufficiently large wall surface, you can also achieve a clear directional effect down to the deep bass range.

The wavelengths of the signal in the deep bass range are so large that the membrane deflections during wave field synthesis are largely synchronized even over several modules. Despite its large diameter, each individual membrane is much smaller in its entire working range than the wavelength of the signal generated. This is why the efficiency in the bass range also benefits from the arrangement of the individual sound transducers in the modular structure of a two-dimensional radiator surface.

The exemplary structure is therefore designed as a three-way module 7. The volume required for the bass transducer 73 can only be arranged behind the transducers for the medium and high frequency ranges 71, 72. The problem arises that the sound pressure generated has to find its way to the front of the flat sound transducer arrangement 1. The continuity of the upstream radiator surface may only be disturbed as little as possible because this creates diffraction effects with corresponding side lobes in the directional characteristic.

As can be seen in FIG. 8, the exemplary solution is therefore designed as a double-ventilated acoustic band-pass filter device 731, 732. The two channels leading to the front interrupt the structure of the high-tone transducers 72 and mid-tone transducers 71 only to a tolerable extent, but the functional principle of the double-ventilated ones enables an efficiency with which the bass range does not counteract the high sound pressure of the upstream sound transducers. Arrangement 1 for the mid and high range falls. In principle, it would also be possible to arrange tweeters in the area of the openings of the double-ventilated bandpass system if they are included in the calculation of the system. However, the air movement in the ducts in the example shown is so strong that audible turbulence noises are to be expected. The high efficiency of the double ventilated bandpass 731, 732 bass transducer is inherently linked to the restricted bandwidth and a non-linearity of the phase response.

With the emitted wavelength of several meters, both openings in the front can be viewed almost as a common acoustic center. This enables a correction over time without creating an inhomogeneous field in the transition area. However, a time correction at the large wavelengths in the range increases the latency of the system significantly. This becomes a problem with every live performance. Here it must be weighed whether a low latency of the system or a linear phase response has priority. Compromises or different setups are possible here.

Basically, one can speak of a two-dimensional sound transducer arrangement if the individual sound transducers are not only arranged in a row (linear). For example, a slight offset of individual sound transducers perpendicular to the linear extension can usually be neglected.

When speaking of a three-dimensional sound transducer arrangement, in addition to the planar arrangement, the arrangement of individual sound transducers perpendicular to the surface is also important. The entire surface can also be bent or curved.

In this sense, the embodiments described above can be referred to as three-dimensional sound transducer arrangements, for example according to FIG. 8. With these Embodiments, it depends on the relative distance between the individual sound transducers.

In FIG. 9, a modular sound transducer system is shown as an example, in which a multiplicity of sound transducer arrangements - as described above - are used as modules. In principle, the sound transducer system can have more columns and / or more rows.

In FIG. 10, an arrangement of several second sound transducers 12 is shown, which are also mounted in the air duct of the acoustic low-pass filter device of the first sound transducer 11. As a result, the air duct with the oscillating air mass 54 is divided into several sub-areas. The total air mass in the air duct remains unchanged. However, there is no longer a single acoustic center of the acoustic low-pass filter device, but rather several air outlets 56. Each of these air outlets 56 forms the starting point of an elementary wave 57 according to Huygens' principle.

In the schematic illustration, these elementary waves 57 each have the same radius, that is to say they have the same time delay as the elementary wave that emanates from the acoustic center of the first sound transducer 58. It is clearly visible that these elementary waves 57 diverge significantly from the elementary wave 59 of one of the second sound transducers 12 in the acoustic center of the first sound transducer 11 with increasing deviation from the center line. However, they remain distributed symmetrically around this elementary wave 59. This means that the pressure maximum of the wavefront of the elementary waves 57 emanating from the multiple acoustic centers (ie acoustic centers at the air outlets of the distributed channels of the acoustic low-pass filter device) is in phase with the one elementary wave 59. The wavefront formed together thus remains homogeneous. A common synthesized wavefront 4 is created. List of reference symbols

I transducer arrangement

I I first sound transducer 12 second sound transducer

211 acoustic center of the first transducer

212 acoustic center of the second transducer

311 Elementary wave of the first transducer

312 Elementary wave of the second transducer

3111 Direction of propagation of the elementary wave of the first sound transducer. 3121 Directional characteristic of the second sound transducer

4 synthesized wavefront

5 acoustic low pass filter device

51 Air chamber of the acoustic low-pass filter device

52 Neck / constriction of the acoustic low-pass filter device 521 Opening of the flals

53 springy air volume

54 oscillating air mass

511 cone

512 more air chambers

531 cone volume

532 more air volume

55 plate

551 opening in the plate

56 air outlets

57 Elementary wave of the acoustic centers at the air outlets of the acoustic low-pass filter device

58 common acoustic center of the first and second transducers

BO 59 Elementary wave of the second transducer in the acoustic center of the acoustic low pass of the first transducer

6 patterns

611 first sample

612 second pattern

7 Three way module

71 mid-range transducers

711 Chamber volume of the mid-range transducer

72 dome transducers

721 Dome of the dome sound transducer

73 bass transducer

731 front channel of the bandpass filter 7311 front volume of the bandpass filter

732 rear channel of the bandpass filter 7321 rear volume of the bandpass filter

8 Direction to a distant listener 81 Main axis of the transducer arrangement

9 elementary waves of the second transducer

Bl

Claims

1. Sound transducer arrangement based on the principle of wave field synthesis or a beamforming method, in particular for aligning at least one sound wave front, characterized in that at least one first sound transducer (11) is coupled to an acoustic low-pass filter device (5).

2. Sound transducer arrangement (1) according to claim 1, characterized in that the at least one acoustic low-pass

Filter device (5) has a mechanical device.

3. Sound transducer arrangement (1) according to claim 1 or 2, characterized in that the at least one acoustic low-pass

Filter device (5), a resilient air volume (52) in an air chamber (51) in front of the respective first sound transducer (11).

4. Sound transducer arrangement (1) according to claim 3, characterized in that a conical volume (511) of the at least one first sound transducer (11) is part of the air chamber (51) or corresponds to this.

5. Sound transducer arrangement (1) according to at least one of the previous ones

Claims, characterized in that the at least one acoustic low-pass filter device (5) has an oscillating air mass (54) in a neck or a comparable narrowing of the air outlet (52).

6. Sound transducer arrangement (1) according to claim 5, characterized in that an opening (551) in a plate (55) in front of the respective at least one first sound transducer (11) as an opening (54) of the Neck (52) of the at least one acoustic low-pass filter device (5) or as the neck (52) itself.

7. Sound transducer arrangement (1) according to at least one of claims 5 to 6, characterized in that the neck (53) of the at least one acoustic low-pass filter device (5) has a circular cross-section.

8. Sound transducer arrangement (1) according to at least one of claims 5 to 7, characterized in that the neck (53) of the at least one acoustic low-pass filter device (5) has a polygonal cross section or an opening in the sound transducer arrangement (1 ), which is arranged in front of the at least one first sound transducer (11).

9. Sound transducer arrangement (1) according to at least one of the preceding claims, characterized in that the at least one first sound transducer (11) is designed as a mid-range sound transducer, as a low-mid-range sound transducer and / or low-frequency sound transducer.

10. Sound transducer arrangement (1) according to at least one of the preceding claims, characterized in that a plurality of first sound transducers (11) of the same or different design are arranged in a first pattern (611) relative to one another, in particular in a grid pattern.

11. Sound transducer arrangement (1) according to claim 10, characterized in that further sound transducers (12), in particular tweeter sound transducers, are arranged in a second pattern (612) relative to one another, in particular in a grid pattern.

12. Sound transducer arrangement (1) according to claim 10 and 11, characterized in that the first pattern (611) and the second pattern (612) represents a superposition of two grid patterns (6).

BB

13. Sound transducer arrangement (1) according to at least one of the preceding claims, characterized in that the at least one acoustic low-pass filter device (5) has a Helmholtz resonator (5).

14. Sound transducer arrangement (1) according to claim 13, characterized in that the at least one Helmholtz resonator (5) has the property that the numerical value of the ratio of the area of the outlet opening (54) to the product of the volume of its air chamber (51) and the length of its neck

(53) is between 100 and 5000, with the area and volume in

Square or cubic meters, and the length of the neck is given in meters.

15. Sound transducer arrangement (1) according to at least one of the previous ones

Claims, characterized in that the acoustic centers (211) of the first sound transducers (11) and the respective acoustic low-pass filter devices (5) coupled therewith and the acoustic centers (212) of second sound transducers (12) of the sound transducer arrangement (1) are arranged in a surface, in particular a plane.

16. Sound transducer arrangement (1) according to at least one of the previous ones

Claims, characterized in that the first acoustic center (211) of the respective first sound transducer (11) can be displaced by the at least one acoustic low-pass filter device (5), in particular for setting the spatial radiation characteristics of the sound transducer arrangement (1) for a homogeneous Structure of the elementary waves (312, 311) of the sound transducer arrangement.

17. Sound transducer arrangement (1) according to claim 16, characterized in that the direction of displacement of the first acoustic

Center (211) of the at least one first sound transducer (11) is collinear to the direction of propagation of an elementary wave (311) generated by the at least one first sound transducer (11).

18. Sound transducer arrangement (1) according to claim 16 or 17, characterized in that the displaced acoustic center (211) of the at least one first sound transducer (11) at the level of the height of a second sound transducer (12) of the sound transducer arrangement ( 1) and / or that the acoustic center (212) of a second sound transducer (12) of the sound transducer arrangement (1) lies at the level of the level of the displaced acoustic center (211).

19. Sound transducer arrangement (1) according to at least one of the preceding claims, characterized in that a control of at least one second sound transducer (12), in particular a tweeter sound transducer of the sound transducer arrangement (1) is set up to an additional phase rotation of a signal of the at least one first sound transducer (11), (5) and (211), which is created by coupling with the acoustic low-pass filter device (5), so that the elementary waves (311, 312) overlap to form a common wavefront (4) .

20. Sound transducer arrangement (1) according to at least one of the previous ones

Claims, characterized in that the cutoff frequency of the at least one acoustic low-pass filter device (5) can be tuned above a crossover frequency of a transmission range of the respective at least one first sound transducer (11).

21.Sound transducer arrangement (1) after at least one of the previous ones

Claims, characterized in that the outlet of an air duct with its oscillating air mass, which as the acoustic center is the starting point of the elementary wave of the at least one first sound transducer together with a loudspeaker chassis and the acoustic low-pass, is in the plane of the acoustic centers of second sound transducers, in particular of high-frequency transducers. Transducers ends.

22. Sound transducer arrangement (1) according to at least one of the preceding claims, characterized in that the acoustic low-pass filter device (5) is designed as a function of the fact that at least one second sound transducer is the cutoff frequency of the at least one first sound transducer (11) and the the upstream acoustic low-pass filter device (5) if it is wholly or partially mounted in the area of the air outlet of the acoustic low-pass filter device (5).

23. Sound transducer arrangement (1) according to at least one of the preceding claims, characterized in that the second sound transducer (12), in particular for the high frequency range, can be aligned differently from the main axis of the system, with the aim of reproducing for distant listeners (8), which are far away from the main axis (81) in the radiation direction of the array, to be linearized.

24. Sound transducer arrangement (1) according to at least one of the preceding claims, characterized in that the sound transducer arrangement (1) has at least one three-way module (7) which has dome tweeter sound transducers (72) which are used for audio transmission of the upper frequency spectrum can be used, and which are mounted in groups on printed circuit boards in such a way that their distance from one another is less than the distance between the mid-range loudspeakers in order to ensure reproduction largely free of aliasing effects and - which has at least one bass transducer (73) which is arranged behind the high-frequency sound transducers (72) and mid-range sound transducers (71), and the sound pressure of which can be implemented as a double-ventilated bandpass (731, 732).

25. Modular sound transducer system, characterized by at least two sound transducer arrangements (1) according to at least one of claims 1 to 25 as modules.

26. Modular sound transducer system according to claim 23, characterized in that the at least two sound transducer arrangements (1) are arranged such that the radiating surfaces of the respective sound transducer arrangements are arranged in one plane, are part of a curved surface or approximate a curved surface.

27. A method for operating a sound transducer arrangement (1) according to the principle of wave field synthesis, characterized in that the signal of the at least one first sound transducer system (11), (5) and (211), the sound transducer arrangement (1) with each of an acoustic low-pass filter device (5) is filtered.

28. The method according to claim 27, characterized in that the at least one acoustic low-pass filter device (5) displaces the acoustic center (211) of the respective at least one first sound transducer (11).

29. The method according to any one of claims 27 or 28, characterized in that the control of at least one second sound transducer (12), in particular Flochton sound transducer, the sound transducer arrangement (1) is adapted, in particular delayed to an additional phase rotation of a signal of the at least one first sound transducer (11) which is created by coupling the at least one first sound transducer (11) to the at least one acoustic low-pass filter device (5), so that the elementary waves (311, 312) superimpose to form a common wavefront (4) .

30. The method according to at least one of claims 27 to 29, characterized in that at least one second sound transducer (12), in particular Flochton sound transducer, the sound transducer arrangement (1) in Area of its free air resonance is coupled, and not as usual an octave above its natural resonance, whereby the improved adaptation of the sound transducers in the sound transducer arrangement (1) to the load resistance of the air in a sound transducer arrangement (1) is used according to the principle of wave field synthesis .

31. The method according to at least one of claims 27 to 30, characterized in that a temporal correction between the low-frequency range and the low-mid-range is carried out in the low-bass range in order to improve the phase response, with different setups either the one phase response that is as linear as possible or one as possible may prefer low system latency or a compromise between the two.