EP3005732B1 - Device and method for spatially selective audio playback - Google Patents

Description

The present invention relates to a space-selective audio reproduction, e.g. of different audio signals to different listeners or listener groups located in different locations of a room.

The reproduction of audio signals over several speakers, typically organized as an array, is a common practice. By replicating the signal and recovering the loudspeaker signals by an individual modification such as, the application of a delay and a change in amplitude, generally also described with filtering, the shape of the sound field radiated by a loudspeaker can be purposefully influenced, such as e.g. for the purpose of deliberately sounding certain areas. These techniques are referred to below as beamforming. This technique also allows multiple audio signals to be played back simultaneously with different directional characteristics by producing individual filtered speaker signals for all signals, which are summed up loudly before playback. This allows a room-selective reproduction can be achieved in which several areas, so-called "sound zones" are sonicated with different signals, the mutual influence of the sound reproduction with each other or to other zones, so-called "quiet zones", in which silence should prevail as possible, is minimized.

There are a variety of algorithms for determining beamforming filters. In addition to those applying only amplitude weights and / or delays, there are also methods based on frequency-dependent filtering. These are often based on optimization techniques and allow the flexible specification of a desired radiation behavior, such as a selectable emission direction or the suppression of radiation in definable areas, according to the above "quiet zones". Despite such beamforming algorithms, the effectiveness of space selective sonication, particularly the suppression of audible interference between acoustic zones, is often limited and does not allow for acceptable quality. The main reasons for this are the limitations of the speaker arrays, a desired directional behavior over the the frequency range used, the influence of the playback room, as well as errors resulting from limited robustness of the beamforming filters to speaker fading, signal amplitudes, etc. This limits the possibilities for a room-selective reproduction via physical and signal-processing measures.
It would be desirable to have a concept for space-selective audio reproduction at hand, which makes it possible to achieve a cleaner separation of an audio signal provided for this area from one or more other superimposed reproduced audio signals at a certain area of a public address area.
US 2010/0158263 A1 teaches station-independent frequency band-selective amplification / attenuation of signals to be reproduced in order to achieve a separation of the reproduction which is improved according to the masking aspect.

US 2012/0020480 A1 describes an improvement in the directional characteristic of a loudspeaker array at low frequencies goes. It is proposed to copy or amplify fundamental harmonics from low frequencies into the high frequencies, making use of the psychoacoustic phenomenon that hearing higher harmonics of a signal results in an auditory illusion of hearing the missing fundamental. Accordingly, harmonics are amplified to fundamental frequencies and the fundamental frequencies are again reduced, whereby the better directional characteristic of loudspeaker arrays in higher frequency ranges is utilized. In addition, it is suggested that the masking noise could be used to obscure signal portions of the directionally transmitted audio signal at locations where this audio signal is not supposed to be audible according to the directional broadcast.
EP1699259 describes an audio output device having a measuring means for measuring the levels of a plurality of input audio signals; a sound level adjusting means for adjusting the levels of the input sound signals configured to adjust the gains based on the levels measured by the measuring means and outputting a plurality of adjusted sound signals of equal magnitudes; and an array speaker unit adapted to receive a plurality of tones in accordance with the plurality of matched ones Emitting sound signals respectively outputted to different directivity characteristics by the sound level adjusting means, a first sound being directed toward a first focal point and a second sound being directed toward a second focal point different from the first focus point; wherein the measuring means is configured to divide the plurality of input audio signals into a plurality of frequency bands to measure the levels, and the audio level adjusting means is adapted to adjust and output gains so as to cause the plurality of adjusted audio signals to be equal Having magnitudes for each of the frequency bands based on the measured levels of the respective frequency bands.

The object of the present invention is to provide such a concept.

The object is solved by the subject matter of the appended independent claims.

The core idea of the present invention is to have realized that a better separation of a first audio signal in a first area of a PA area of a plurality of loudspeakers can be achieved by the version of the first area resulting from the space-selective reproduction of the audio signals Calculating a masking threshold depending on the version of the audio signal to be separated from the one or more other audio signals in that area and depending on a comparison of the masking threshold with the version of the one or more other, ie interfering , Audio signals, the output of the audio signals for space-selective playback is influenced to the outputs of the plurality of speakers. The calculation or estimation of the audio signals in this first area can also be illustrated as a simulation of the sound propagation in this first area and thus the element for its execution as a calculator or simulator. The separation of the audio signals to the first area of the PA area already enabled by the room-selective reproduction can thus be improved by evaluating the masking threshold by calculating or simulating the versions of the audio signals resulting from the room-selective reproduction. The influencing of the space-selective reproduction to avoid or reduce the "violation" of the masking threshold at the first area of the public address area can be carried out in different ways, such as by frequency-selective reduction of each interfering other audio signal in frequency ranges where the respective simulated other audio signal exceeds the masking threshold. In addition, it is possible to amplify the actually interesting audio signal at corresponding frequency ranges. In addition, it would also be conceivable to vary a beam shaping of the actually interesting (first) audio signal or both audio signals, depending on the comparison with the masking threshold.

Fig. 1

ein Blockschaltbild einer Vorrichtung zur raumselektiven Wiedergabe zeigt;

Fig. 2

eine Skizze zur Veranschaulichung möglicher Maßnahmen des Anpassers aus Fig. 1 zeigt;

Fig. 3

eine Skizze zur Veranschaulichung einer Maßnahme des Anpassers von Fig. 1 gemäß einem Ausführungsbeispiel veranschaulicht;

Fig. 4

ein Blockschaltbild einer herkömmlichen Vorrichtung zur raumselektiven Wiedergabe zeigt; und

Fig. 5

ein Blockschaltbild einer Implementierungsvariante des Ausführungsbeispiels von Fig. 1 mit Ausgangspunkt zeigt.

Predictive embodiments are the subject of the dependent claims. Preferred embodiments of the present application are explained in more detail below with reference to the drawings, in which

Fig. 1

shows a block diagram of a device for space-selective reproduction;

Fig. 2

a sketch to illustrate possible measures of the fitting out Fig. 1 shows;

Fig. 3

a sketch to illustrate a measure of the adapter of Fig. 1 illustrated according to an embodiment;

Fig. 4

shows a block diagram of a conventional device for space-selective reproduction; and

Fig. 5

a block diagram of an implementation variant of the embodiment of Fig. 1 with starting point shows.

Fig. 1 shows a device for space-selective audio playback according to an embodiment. It is indicated generally by the reference numeral 10. The apparatus 10 comprises an input 12 for at least a first audio signal 14 ₁ and a second audio signal 14 ₂ and an output 16 for a plurality of loudspeakers 18. A beamforming processor 20 of the apparatus 10 is connected between the input 12 on the one hand and the output 16 on the other hand designed to output the first and second audio signals 14 ₁ and 14 ₂ to the speakers 18 for room-selective reproduction via the output 16. The loudspeakers 18 are capable of sonicating a PA area 22, such as an area surrounded or directed by the loudspeakers at their intended speaker locations, or generally an area which is sonicated by at least one of the loudspeakers 18 , The sonication area may be a fictitious space relative to the configurations of fictitious speaker positions of the speakers 18, such as a virtual one PA area without reflective surfaces, or around a real PA area, which reflection effects, such as on walls or the like, may have.

"Space selective" playback of the audio signals 14 ₁ and 14 ₂ on the speakers 18 shall mean that the audio signals are not simply output in the form of superimposed copies to the loudspeakers 18, but that they are as described in the introduction to the present application , are output via the loudspeakers 18 filtered by means of, for example, speaker-specific delays and / or amplitude modifications or in general filtered by a loudspeaker-individual filtering and indeed different for the audio signals 14 ₁ and 14 ₂ , so that there is at least a first area 24 of the public address area, which differs from the second audio signal 14 ₂ compared to the first audio signal 14 _{1 is} less or not at all sonicated. There may also be a second area 26 in which it behaves the other way around, ie the first audio signal 14 ₁ less or not at all irradiates this area 26 compared to the second audio signal 14 ₂ due to the space-selective reproduction via the loudspeakers 18. Afterwards it is pointed out that the juxtaposition of more than two superimposed reproduced audio signals is possible.

Under optimal conditions, it could be that the separation of the first audio signal 14 ₁ at the first area 24 from the other audio signal 14 ₂ goes so far that a listener in this area 24 does not hear the other audio signal 14 ₂ . Unfortunately, however, room selectivity over the rendering through the speakers 18 is limited, which may be due to real reflections or simply a limited overall extent of distribution of the speaker 18 positions. The other elements included in the device 10 are to enhance "space selectivity" in this sense. The details will be discussed below.

Before that, however, it should be mentioned briefly that the audio signals 14 ₁ and 14 _{2 may be present} at the input 12 in any form, such as analog or digital, in separate or in m / coded form or in a parameterized downmix form, uncompressed or compressed The same applies to the loudspeaker signals for the loudspeakers 18 at the output 16. Loudspeaker-individual loudspeaker signals for the loudspeakers 18 can be output via the output 16 separately, in analog or digital, compressed or uncompressed, already amplified , only pre-reinforced or unreinforced Similarly, it would be possible for the loudspeaker signals to be output in compressed form in a downmix, along with spatial cues parameters, such as in MPEG surround or SAOC encoded form. For example, the beamforming processor 20 initially processes the incoming audio signals 14 ₁ and 14 ₂ completely separate from each other to produce a set of loudspeaker signals for the loudspeakers 18 to each of them so that each loudspeaker signal for the respective audio signal has a particular one for the respective loudspeaker position of the respective one Speaker individual filtering, such as delay and / or amplitude modification experienced. Only at the end, for example, the thus obtained from the individual speaker signals loudspeaker signal sets per channel or speakers are superimposed with each other. This is also illustrated once more in the following figures.

Although the area 24 and the optional area 26 in Fig. 1 By way of example, in a circular fashion, ie as two-dimensional regions bounded transversely thereto both in a direction passing through the speakers 18 and in a direction, the term "space selectivity" should of course also be understood broad enough to allow only "angle selectivity" in the sense that the audio signal individual processing within the beamforming processor 20 results in the audio signals 14 ₁ and 14 ₂ being emitted into different solid angle ranges as viewed from the loudspeakers 18. Such angular selectivity may be to influence the far field radiation of the loudspeaker setup be interpreted. In a small distance to the speaker setup (in relation to the size of the speaker setup, ie in the geometric near field) is also a targeted modification of the radiation in a two-dimensional area conceivable.

As will be discussed in more detail below, beamforming processor 20 may be fixed or optimized for space selective playback. In other words, the spatial selectivity of the reproduction of the beamforming processor 20 may be constant. It may be optimized in advance to the area 24 or the areas 24 and 26, ie to the effect that in the area 24 only the first audio signal 14 ₁ and, if provided, in the area 26 only the second audio signal 14 ₂ from a listener in the respective Area is audible. The optimization then defines the aforementioned delays, amplitude modifications and / or filters, such as FIR filters, for the individual channels or speakers 18, and the beamforming processor 20 may be hard-wired, for example, or fixed in software or programmable Hardware implemented to accomplish the space-selective playback via the output 16 to the speakers 18. However, it is also alternatively possible that the beamforming processor is also adjustable in terms of speaker-individual processing (delay, amplitude modulation or filtering) for one or more of the audio signals 14 ₁ , 14 ₂ . In general terms, the beamforming processor 20 can be adjusted or influenced at the output 16 with regard to its space-selective reproduction of the audio signals 14 ₁ , 14 ₂ , as will be described in more detail below. In addition or as an alternative, this setting can also be achieved by audio-signal-specific, frequency-selective modification / influencing of individual or all audio signals which acts on all loudspeakers / channels, as will also be described below. It is the aforementioned controllability of the beamforming processor 20 that uses the components of the apparatus 10 described below to enhance the separation of the first audio signal 14 ₁ in the area 24 from the other audio signal 14 ₂ .

The device 10 comprises, in addition to the components described so far, a calculator 28, a masking threshold calculator 30 and an adjuster 32. The calculator 28 is also connected to the input 12 and is designed to use a propagation model for the audio signals 14 ₁ and 14 _2, respectively to calculate the version of the respective audio signal 14 ₁ or 14 ₂ resulting from the room-selective reproduction in the first area 24, ie the version 34 _{1 of} the audio signal 14 ₁ reproduced at the location 24 and also the version 34 _{2 of} the audio signal 14 reproduced at the location 24 ₂ . The masking threshold calculator 30 receives the socket 34 ₁ and is designed to calculate a masking threshold 36 as a function of this, and the adjuster 32 receives the socket 34 _{2 of} the other audio signal and optionally also the socket 34 _{1 of} the first audio signal 14 ₁ and is designed to in order to influence the output of the first and second audio signals for space selective reproduction via the output 16 to the loudspeakers 18, depending on a comparison of the masking threshold 36 with the version of the second audio signal 34 ₂ , by the adjuster 32 controlling the beamforming processor 20 as appropriate an arrow 38 is indicated. In other words, an output of the adder 32 is connected to a control input of the beamforming processor 20.

Calculators 28, masking threshold calculators 30, and fitters 32 may each be implemented in software, programmable hardware, or in hardware. For example, the calculator 28 may use propagation models that are also for optimization the internal, channel / speaker-individual processing of the audio signals 14 ₁ , 14 ₂ within the beamforming processor 20 could have been used. The calculator 28 calculates or estimates, for example, as will be described in more detail below, the sound events generated at the location 24 by the first audio signal 14 ₁ and the second audio signal 14 ₂ . For example, it can take account of the channel / loudspeaker-individual processing of the audio signals 14 ₁ , 14 ₂ within the beamforming processor 20 and the positions of the loudspeakers 18 and optionally further parameters, such as emission characteristics and / or orientation of the loudspeakers 18. The calculator 28 calculates the sound events, for example, measured or represented in sound pressure, amplitude or the like, and possibly frequency-dependent, ie for different frequencies. In the case of constant / fixed channel / speaker-individual processing of the beamforming processor 20, the calculator 28 may perform the simulation in a constant / fixed manner. The consideration of the adaptation to the channel / speaker-individual processing of the processor 20 is then based on the appropriate design of the propagation model, which the calculator 28 uses to calculate the sockets 34 ₁ , 34 ₂ . The propagation model can thus also take into account the parameters just mentioned. The sockets 34 ₁ and 34 ₂ may in turn be output by the calculator 28 in any form, ie analog or digital, compressed or uncompressed, in the time domain or in the frequency domain or the like.

The Maskierungsschwellenberechner 30 calculates a masking threshold depending on the version 34 _1, ie the audible version of the audio signal 14 ₁ 24 at the location As is indicated by a dotted arrow 40 which Maskierungsschwellenberechner a background audio signal, in addition to the socket 34 ₁ (for example Noise or driving noise) for masking threshold calculation.
The calculation takes into account temporal and / or spectral auditory masking effects. The calculated masking threshold thus indicates, depending on the frequency, how much the socket 34 _{1 of} the audio signal 14 ₁ at the location 24 is able to make other audio signals inaudible to a listener at the location 24 by covering the latter. For example, the masking threshold calculator 30 may be configured to calculate the masking threshold at a frequency resolution that becomes increasingly coarse as the frequency increases, ie, as the frequency bands increase in frequency as the frequency increases, such as in a Bark frequency resolution.

The adjuster 32 compares the masking threshold 36 with the socket 34 _{2 of} the second audio signal 14 ₂ and thus determines, for example, whether the second audio signal 14 ₂ is audible to a person at the location 24, ie if the second audio signal at any frequency is the masking threshold exceeds. If so, the adjuster 32 takes countermeasures and appropriately controls the beamforming processor 20. Several examples of such controls have been previously indicated. Referring to the following figures, this is illustrated once again.

Fig. 2 For example, in a graph plotted against the frequency f, the masking threshold 36, the bezel 34 _1, and the bezel 34 _{2 are shown} in a virtual, thickness-measuring scale. A frequency range 42, in which currently the interfering audio signal 14 ₂ or the version 34 ₂ resulting at the location 24 according to the simulation exceeds the masking threshold 36, is illustrated by way of example. A possible countermeasure would be that the adjuster 32 controls the beamforming processor 20 in such a way that the second audio signal 34 _{2 is} reduced in this frequency range 42, as indicated by an arrow 44. Additionally or alternatively, the adjuster 32 could control the beamforming processor 20 in such a way that the first audio signal 14 _{1 is} amplified in this frequency range 42-or, if appropriate, even beyond this frequency range 42, as indicated by an arrow 46. Reduction 44 and / or gain 46 are preferably made such that the amount of gain / reduction does not have abrupt jumps in time and / or frequency. The extent or the form of reduction and / or amplification is smoothed, for example temporally and / or spectrally.

The previously referring to Fig. 2 explained possible measures of the adapter 32 against audibility of the version 34 ₂ at the location 24 in the space-selectivity sense global measures or channel / speaker-global or for all channels / speakers 18 equally acting measures. It will be shown later that the beamforming processor 20 executes, for example, the gain 46 and / or reduction 44 in advance on the respective incoming audio signal 14 ₁ or 14 ₂ and only then the channel / speaker individual processing of the equally pre-processed audio signals for the space-selective playback. Additionally or alternatively, as already indicated above, the adjuster 32 may be formed to vary the beam shaping itself depending on the aforementioned comparison with the masking threshold 36. To illustrate this, refer to Fig. 3 taken.

Fig. 3 FIG. 12 shows that the beamforming processor 20 has multiple channel / speaker options or modes of individual beamforming processing of the audio signals 14 ₁ and 14 ₂ , which are indicated here by way of example at 48 ₁ -48 _{N in} different modes. One of these, for example the beamforming processing according to FIG. 48 ₁ , could be, for example, an optimal spatial-selective reproduction processing, ie possibly leading in place and frequency to the best suppression of the audio signal 14 ₂ or 34 ₂ at the location 24. However, the other modes 24 ₂ - 48 _N may possibly lead to similarly good separations or even to equally good or even optimal according to other or differently weighted criteria. For example, all modes 48 ₁ - 48 _N could have differences in the quality of suppression for different frequency ranges, and in this case, the adder 32 could be dependent on the comparison with the masking threshold 36 and a location of an interval 42 in which the masking threshold 36 is violated is present, change a currently selected channel / speaker-individual processing mode or change from the same to another, in Fig. 3 For example, an arrow 50 should indicate the selection of a currently selected mode 48 ₁ -48 _N and a double arrow 52 should change that mode currently used by the beamforming processor 20 to another depending on the aforementioned comparison with the masking threshold 36 another might be associated in the beamforming processor 20 with a speaker / channel individual fading between a loudspeaker signal received with the last and a new mode with the new mode.

By calculation 28, masking threshold 30 and adjuster 32 is the device 10 of Fig. 1 thus able to improve the suppression of another audio signal 14 ₂ at a location 24 of the PA area of the loudspeaker setup 18 with respect to a constant, optimized beam shaping separation. Various measures are possible to avoid any degradation of the audio quality of the first and / or the second audio signal at location 24 and / or location 26 by the masking threshold controlled modification. For example, as already mentioned above, the extent of gain 46 and / or reduction 44 can be limited both in terms of its absolute value, ie the strength of the gain 46 and / or magnitude of the reduction 44, but also the change of this severity in time and / or frequency. In the case of using the possibility according to Fig. 3 For example, fading could be used to switch from one mode to the other mode. On this occasion it is worthwhile It should also be pointed out that, in addition to the processing delay resulting from the space selective playback operations in the beamforming processor 20, a delay may be provided to make a processing delay adjustment to the processing delay caused by the series of processing in calculator 28, masking threshold calculator 30 and adjuster 32 is caused. In this way, it is possible for the adjustments made by the adjuster 32 to be timely synchronized to the audio signals 14 ₁ and 14 ₂ from which the adjustment control data was obtained. Such additional delay in the beamforming processor 20 path from processing in the path along the calculator 28, masking threshold calculator 30, and aligner 32 could also be used to facilitate the aforementioned fading transitions between different beamforming modes 48 ₁ -48 _N.

Before describing yet a concrete embodiment of a device for space-selective reproduction in order to describe possible implementations of the elements already mentioned above, it should also be pointed out that in the case of mode switching according to FIG Fig. 3 Also, if necessary, a continuous change of the channel / speaker-individual processing is possible by a corresponding parameter by the modification 52 is not discontinuous, but perhaps continuously changed. As mentioned, behind the channel / loudspeaker-individual processing 48 there is for example a set of delays for each channel / loudspeaker for at least the audio signal 48 ₂ but possibly also both audio signals 14 ₁ and 14 ₂ , and / or corresponding amplitude changes or filter coefficients for FIR. Filter.

Finally, it should be pointed out that more than just two audio signals 14 ₁ and 14 ₂ can be provided. This is indicated by a dashed arrow 54 in FIG Fig. 1 indicated. The foregoing description is readily applicable to this case. Additional audio signals 54 would, for example, be treated as the audio signal 14 ₂ , ie as audio signals whose reproduction at location 24 should be inaudible to a listener at this location 24.

Once again, in other words, the above embodiment makes it possible to improve the perceived quality of a spatial-related replay by incorporating psychoacoustic effects. It exploits that an audio signal audibility of components of another, quieter signal. This effect is called masking . For example, this plays a central role in lossy audio coding. In psychoacoustics, a distinction is made between masking in the time domain and in the frequency domain. In masking in the time domain, a loud signal, the so-called masker, masks other components that appear shortly after or within narrow limits even before this sound event. In the frequency domain masking, a component of a particular frequency masks other components of similar frequency and amplitude. The threshold to which masking occurs depends on the frequency and absolute level of the marker and the distance between the frequencies of the masker and other signal. The masking thresholds and thus the decision as to whether a signal component is masked are determined by psychoacoustic models. Such psychoacoustic models are used by masking threshold calculator 30.

As already announced above, in the following a possible implementation for the embodiment of Fig. 1 described. The technical details of this should be individually based on the individual elements of Fig. 1 be transferable. However, before referring to this implementation Fig. 5 is described with reference to Fig. 4 described the basic setup for space-selective playback, which then according to the above embodiment with the implementation of Fig. 5 is improved. Fig. 4 shows how two audio signals S ₁ (t) and S ₂ (t) via two beamforming filter sets 60 ₁ and 60 ₂ , a summation stage 62 and a speaker array of speakers 18 are processed so that these signals in the areas Z ₁ and Z ₂ , ie the audio signal S ₁ (t) mainly in the area Z ₁ and the audio signal S ₂ (t) mainly in the area Z ₂ . Due to the physical limitations of the setup, however, an ideal separation is not possible, as has already been described above. The components 60 ₁ , 60 _2, and 62 form a simple beamforming processor 64 that, for example, operates constantly and is optimized to perform the aforementioned separation. The beamformer 60 ₁ beamforms the incoming audio signal S ₁ (t) to produce a set of loudspeaker signals for that signal, and the same does beamformer 60 ₂ for the second audio signal S ₂ (t). Both beamformers 60, _1.2 output their loudspeaker signal sets to the summer 62, which individually adds the same loudspeaker signals to the loudspeakers 18.

Fig. 5 now shows how the setup of Fig. 4 according to the embodiment of Fig. 1 can be improved. The device of Fig. 5 is indicated at 10 and otherwise the reference numerals of Fig. 1 taken over to each other in their function corresponding parts to Fig. 1 display. As can be seen, the beamforming processor 20 is of Fig. 5 opposite the starting point of Fig. 4 by way of example only by inserting a Pegelanpassers 66 in the signal path of the interfering audio signal S ₂ modified here exemplarily on the input side of the beam former 60 ₂ , although for all channels / speakers 18 equally acting level adjustment by the level adjuster 66 would also be possible. The level adjuster 66 is controlled by the adjuster 32, with reference to Figs Fig. 2 illustrated reduction 44 perform. Fig. 5 also shows that it is possible to use the in Fig. 1 perform for one of the audio signals performed signal separation of other audio signals for more than one audio signal. In the present case, by means of corresponding propagation models corresponding to the beamformations of the beamformers 60 ₁ and 60 ₂ , the calculator 28 simulates the respective audible version at both locations, namely locations Z1 and Z2, for both audio signals 60 S ₁ and S ₂ . That is why in Fig. 5 a propagation model user ₁ 68 shown, which applies the appropriate propagation models to the audio signal S ₁ and a propagation model 68 users ₂ who undertakes selbiges for the audio signal _S2. For the respective version for which the respective audio signal is provided in the respective location, ie the audible version of the audio signal S ₂ at the location Z ₂ and the audible version of the signal S ₁ at the location Z ₁ , the masking threshold calculator 30 performs a masking threshold calculation and gives the result, ie the respective masking threshold for the location Z ₁ and Z ₂ , ie the masking by the signal S ₁ at location Z ₁ or the masking by the audio signal S ₂ at location Z ₂ , to the control data adaptation or the adjuster 32 further, which in each case reserves the respective disturbing listening versions, ie the audible version of the signal S ₂ at location Z ₁ and the audible version of the signal S ₁ at location Z ₂ .

To face the situation Fig. 4 to improve, the device is after Fig. 5 the masking thresholds of the audibility of the signal S ₂ in zone Z ₁ determined. For this purpose, first the signals resulting from the signals S ₁ (t) and S ₂ (t) in the zone Z _{1 are} determined, such as the magnitudes in the frequency domain. For this purpose, a propagation model is calculated or used, which includes the transfer function of the loudspeaker array of loudspeakers 18. The signals are referred to as S ₁ (t, Z ₁ ) and S ₂ (t, Z ₁ ). As with the psychoacoustic model, the masking thresholds for the audibility of the signal S ₂ (t, Z ₁ ) are determined using the masker S ₁ (t, Z ₁ ). From these Thresholds are determined in a component change values for the magnitudes of the audio signal S ₁ (t) (for certain frequency ranges). In addition to the masking thresholds, other psychoacoustically motivated parameters can be included, such as maximum permissible changes of the signal S ₁ (t) in order to limit the effects of the adjustments by the adjuster 32 to the reproduction of S ₁ (t) in Z ₁ . Optionally, the temporal course of the magnitude change is limited in order to avoid sudden, potentially disturbing changes. The parameters of this timing can also be determined by psychoacoustic parameters.

The same algorithm as just described could be used simultaneously to minimize the influence of S ₁ (t) on the reproduction of S ₂ (t) in zone Z ₂ , as indicated by the fact in FIG Fig. 5 It is indicated that the simulation for calculating the audible versions at location Z _{2 is} performed as well as the calculation of the masking threshold at this location, even though those calculations are performed in Fig. 5 could also be omitted. Accordingly, in Fig. 5 a level adjuster may also be inserted in the signal path of the audio signal S ₁ which is controlled by the adjuster 32 based on a comparison of the masking threshold for the location Z ₂ with the disturbing audio signal S ₁ at the location Z ₂ . Since the adjuster 32 knows about the result of all comparisons, ie the result of the comparison of the masking threshold in Z ₂ with S ₁ at location Z ₂ and the result of the comparison of the masking threshold in Z ₁ with S ₂ at location Z ₁ , the matcher is in capable of making it possible for all locations or areas Z _1/2 to reduce the influence of the respectively interfering signal, ie S ₂ in Z ₁ and S ₁ in Z ₂ , to the desired signal, ie S ₂ in Z ₂ and S ₁ in Z ₁ , to calculate. It may be that the adjuster 32 has to compromise on this, since the disturbances in the individual areas require measures that mean a deterioration in the other area or in the other areas. This trade-off could be influenced by having the matcher 32 prioritize the ranges and associated desired signals so that the negative impact of higher priority signals at their respective destination is realized by other higher priority signals than lower priority signals.

Of course, beyond the number of two audio signals as in the above embodiments, the number of audio signals may also be higher.

The signal flow of the concept or algorithm is in Fig. 5 Thus represented such that from the signals S ₁ (t) and S ₂ (t) by means of an acoustic propagation model, the acoustic Event, such as the sound pressure, the magnitude, etc., is determined in the zone Z ₁ . This propagation model is usually a function of frequency and produces a discrete set of values, each associated with a frequency. In the simplest case, the transfer function of the beamformer 60 ₁ to a point, such as the center of the zone Z ₁ , is used as the propagation model. However, other models such as a weighted average of the magnitude transfer function to a bitmap in Z ₁ may be used. The kernel characteristic of the propagation model is that it translates an input signal S _i (t) to a measure describing the magnitude of the sound incidence resulting from this signal in zone Z ₁ , for each of the considered frequency bands. The division of the audio frequency range into frequency bands can be done differently, but useful are psychoacoustic characteristics oriented divisions, such as Constant-Q or Bark scale. For example, the output values of the psychoacoustic model may be output at a lower frequency than the audio sample rate. This can be done, for example, by sub-sampling or by moving averaging with, for example, decimation. The output values of the masking threshold calculator are in the embodiment of FIG Fig. 5 still raw control data describing a desired level change in the individual frequency bands. These data are also defined over a grid of frequency bands and are usually present at a lower than the audio sampling rate. The raw control data is reworked in the matcher. In this module optional upper and lower limits for the level change of individual frequency ranges can be specified. On the other hand, the timing of the changes can be adjusted, such as by delaying and smoothing the level changes.

The matched control signals of the adaptor are used in the level adjuster to frequency-level level the signal S ₁ (t) before filtering with the loudspeaker-specific beamforming filters in the beamformer 60 ₂ . The level adjuster 66 thus acts as a multi-band equalizer. A function similar to a multiband compressor, or more generally multiband dynamics control, is achieved in conjunction with the timing of the adaptor, but unlike normal use, these units here use a different signal to control the gain values.

As in Fig. 5 In the same way, the signal S ₂ (t) can be adaptively changed in order to reduce the interference of S ₂ (t) into the zone Z ₁ . This is also possible to reduce crosstalk simultaneously. This possibility exists regardless of the details of Fig. 5 of course, more generally for the example of Fig. 1 ,

Optionally, in addition to the above embodiments, a reference signal 40 may be additionally used for extraneous noise such as general background noise level, interior noise in automotive applications, or the like. This signal 40 can be used as an additional input to the masking threshold calculation, as described above. The reference signal 40 is preferably a measured or sensible estimated value for the background noise signal in the "sound zones" 24 or 26 or Z ₁ in Z ₂ .

Furthermore, it is possible to achieve in one (or more) zones only the reduction of the crosstalk from the other sources instead of undisturbed reproduction of a signal.

The above exemplary embodiments thus describe a concept for space-selective reproduction with loudspeaker arrays by psychoacoustic environmental effects or the spatial reproduction of audio signals via a plurality of loudspeakers, which can be arranged, for example, as an array. In particular, it has been described how different audio signals can be radiated into different spatial areas, so that the mutual influence is minimized or significantly reduced. In some embodiments, this has been accomplished by a combination of beamforming algorithms with a psychoacoustic model that modifies the audio signals so that the audibility of the interfering signals is reduced by the psychoacoustic masking by the useful signal.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device. Some or all of the method steps may be performed by a hardware device (or using a hardware device). Apparatus), such as a microprocessor, a programmable computer or an electronic circuit. For some Embodiments, some or more of the most important method steps may be performed by such an apparatus.

Depending on particular implementation requirements, embodiments of the invention may be implemented in hardware or in software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-ray Disc, a CD, a ROM, a PROM, an EPROM, an EEPROM or FLASH memory, a hard disk, or other magnetic disk or optical memory are stored on the electronically readable control signals that can cooperate with a programmable computer system or cooperate such that the respective method is performed. Therefore, the digital storage medium can be computer readable.

Thus, some embodiments according to the invention include a data carrier having electronically readable control signals capable of interacting with a programmable computer system such that one of the methods described herein is performed.

In general, embodiments of the present invention may be implemented as a computer program product having a program code, wherein the program code is operable to perform one of the methods when the computer program product runs on a computer.

The program code can also be stored, for example, on a machine-readable carrier.

Other embodiments include the computer program for performing any of the methods described herein, wherein the computer program is stored on a machine-readable medium.

In other words, an embodiment of the method according to the invention is thus a computer program which has a program code for performing one of the methods described herein when the computer program runs on a computer.

A further embodiment of the method according to the invention is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program is recorded for performing any of the methods described herein.

A further embodiment of the method according to the invention is thus a data stream or a sequence of signals, which represent the computer program for performing one of the methods described herein. The data stream or the sequence of signals may be configured, for example, to be transferred via a data communication connection, for example via the Internet.

Another embodiment includes a processing device, such as a computer or a programmable logic device, that is configured or adapted to perform one of the methods described herein.

Another embodiment includes a computer on which the computer program is installed to perform one of the methods described herein.

Another embodiment according to the invention comprises a device or system adapted to transmit a computer program for performing at least one of the methods described herein to a receiver. The transmission can be done for example electronically or optically. The receiver may be, for example, a computer, a mobile device, a storage device or a similar device. For example, the device or system may include a file server for transmitting the computer program to the recipient.

In some embodiments, a programmable logic device (eg, a field programmable gate array, an FPGA) may be used to perform some or all of the functionality of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor to perform one of the methods described herein. In general, in some embodiments, the methods are performed by any hardware device. This may be a universal hardware such as a computer processor (CPU) or hardware specific to the process, such as an ASIC.

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will be apparent to those skilled in the art be clear. Therefore, it is intended that the invention be limited only by the scope of the appended claims and not by the specific details presented in the description and explanation of the embodiments herein.

Claims (14)

1. Device for spatially selective audio reproduction, comprising
   an input (12) for first and second audio signals (14₁, 14₂);
   an output (16) for a plurality of loudspeakers (18);
   a beamforming processor (20) connected between the input (12), on the one hand, and the output (16), on the other hand, and configured to emit the first and second audio signals (14₁, 14₂) for spatially selective reproduction to the loudspeakers (18) via the output;
   a calculator (28) configured to calculate, by means of a propagation model, for the first and second audio signals (141, 142) a respective version (34₁, 34₂) of the respective audio signal which results from the spatially selective reproduction in a first region (24) of a sonication area (22) of the loudspeakers (18);
   the beamforming processor (20) being configured to achieve emission of the first and second audio signals (141, 142) for spatially selective reproduction to the output by performing beamforming on at least the second audio signal (142);
   characterized in that the device further comprises:

   a masking threshold calculator (30) configured to calculate, via a psychoacoustic model, a masking threshold (36) as a function of the version (34₁) of the first audio signal (14₁); and

   an adaptor (32) configured to influence, as a function of a comparison of the masking threshold (36) with the version (34₂) of the second audio signal (14₂), the emission of the first and second audio signals (14₁, 14₂) for spatially selective reproduction to the loudspeakers (18) via the output (16),

   the beamforming processor (20) comprising several modes for performing beamforming which differ from one another with regard to a quality of suppression of the second audio signal (14₂) at the first region (24) for different frequency domains,

   the adaptor (32) being configured to vary the beamforming by switching from a currently used mode to a different mode as a function of the comparison.
2. Device as claimed in claim 1, further comprising the plurality of loudspeakers (18).
3. Device as claimed in claim 1 or 2, wherein the beamforming processor (20) is configured to perform beamforming (602) on the second audio signal (14₂) so as to obtain a first plurality of loudspeaker signals, and to apply the loudspeaker signals obtained from the second audio signal to the loudspeakers (18) via the output (16).
4. Device as claimed in claim 3, wherein the beamforming processor is configured to subject the first audio signal (14₁) to beamforming (60₁) so as to obtain a second plurality of loudspeaker signals, and to apply the second plurality of loudspeaker signals to the loudspeakers (18) via the output (16) by means of superposition (62) with the first plurality of loudspeaker signals.
5. Device as claimed in claim 4, wherein the beamforming processor (26) is configured to perform the beamforming (60₁, 60₂) on the first and second audio signals differently - for spatially selective reproduction in different regions (24, 26) of the sonication area (22) - so that for each region, one of the audio signals represents a target signal, whereas the respectively other audio signal represents a spurious signal in the respective region.
6. Device as claimed in claim 5, wherein
   the calculator (28) is configured to calculate, by means of the propagation model, for each audio signal and for each of the different regions a respective version of
   the respective audio signal which results from the spatially selective reproduction in the respective region of the sonication area (22) of the loudspeakers (18),
   the masking threshold calculator (30) is configured to calculate a masking threshold (36) for each region of the sonication area as a function of the version, which results from the spatially selective reproduction in the respective region of
   the sonication area (22) of the loudspeakers (18), of that audio signal which represents a target signal for the respective region; and
   the adaptor (32) is configured to influence the emission of the audio signals for spatially selective reproduction to the loudspeakers (18) via the output (16) on the basis of a comparison of the masking threshold (36) for each of the regions with an interference which results from the version (34₂) of that audio signal which represents a spurious signal in the respective region.
7. Device as claimed in claim 6, wherein the number of the audio signals is larger than two.
8. Device as claimed in any of the previous claims, wherein the masking threshold calculator (30) is configured to take into account a background audio signal when calculating the masking threshold as a function of the version (34₁) of the first audio signal (14₁).
9. Device as claimed in any of the previous claims, wherein the adaptor (32) is configured to control the beamforming processor (20) such that within frequency domains in which the version (34₂) of the second audio signal (14₂) exceeds the masking threshold, the second audio signal (14₂) is globally reduced in the spatially selective reproduction.
10. Device as claimed in any of the previous claims, wherein the adaptor (32) is configured to control the beamforming processor (20) such that within frequency domains in which the version (34₂) of the second audio signal (14₂) exceeds the masking threshold, the first audio signal (14₁) is globally amplified in the spatially selective reproduction.
11. Device as claimed in any of the previous claims, wherein the adaptor (32) is configured to limit the change in the emission of the first and second audio signals (14₁, 14₂) with regard to an absolute value and/or with regard to a rate of change of the value of the change.
12. Device as claimed in any of the previous claims, wherein the calculator is configured to take temporal and spectral auditive masking effects into account in the calculation.
13. Method for spatially selective audio reproduction by means of a beamforming processor (20) connected between an input (12) for first and second audio signals (14₁, 14₂) and an output (16) for a plurality of loudspeakers (18), said beamforming processor (20) being configured to emit the first and second audio signals (14₁, 14₂) for spatially selective reproduction to the loudspeakers (18) via the output (16), comprising:

    calculating, by means of a propagation model for the first and second audio signals (14₁, 14₂), a respective version (34₁, 34₂) of the respective audio signal which results from the spatially selective reproduction in a first region (24) of a sonication switch (22) of the loudspeakers (18);

    the beamforming processor (20) being configured to achieve emission of the first and second audio signals (141, 142) for spatially selective reproduction to the output by performing beamforming on at least the second audio signal (14₂);

    characterized by

    as a function of the version (34₁) of the first audio signal (14), calculating a masking threshold (36) via a psychoacoustic model; and

    as a function of a comparison of the masking threshold (36) with the version (34₂) of the second audio signal (14₂), influencing the emission of the first and second audio signals (14₁, 14₂) for spatially selective reproduction to the loudspeakers (18) via the output (16);

    the beamforming processor (20) comprising several modes for performing beamforming which differ from one another with regard to a quality of suppression of the second audio signal (14₂) at the first region (24) for different frequency domains,

    said influencing comprising varying the beamforming by switching from a currently used mode to a different mode as a function of the comparison.
14. Computer program comprising a program code for performing the method as claimed in claim 13, when the program runs on a computer.

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