Apparatus and method for reducing spectral distortion in a system for reproducing virtual sounds through loudspeakers - Patents.com

Abstract

An apparatus (100) for reducing spectral distortion in a system (200) for reproducing virtual sounds through loudspeakers is provided, the apparatus (100) being configured to reduce said spectral distortion by performing adaptive equalization and / or by performing time dynamic equalization.

Description

[Technical field]

[0001] The present invention relates to audio signal coding, processing and decoding, and in particular to an apparatus and method for reducing spectral distortion in a system for reproducing virtual sounds. [Background technology]

[0002] When sound waves are emitted from a speaker to a listener's ear, the sound is modified multiple times, for example by the reflection of the sound waves on walls, so that the sound that reaches the pinna of the ear contains, in addition to e.g. music and speech, also information about the listening environment.

[0003] In addition, sounds arriving from multiple directions are shaped differently in the listener's head and ears. Using this information, the listener's brain can determine the approximate direction and distance of the sound source.

[0004] However, when headphones are used, all such information is usually missing, as the audio is emitted more or less directly to the listener's eardrum, which creates the impression that the sound is generated inside the listener's head, which can be perceived as inconvenient and can result in, for example, spectral coloration, especially when earphones are used for longer periods of time.

[0005] It has been determined that the above-mentioned modifications of the sound waves towards the pinna and eardrum of the listener can be measured and replicated by digital filters, for example by using head-based impulse responses, head-related transfer functions, binaural room impulse responses, and binaural room transfer functions. When such filters are applied to audio signals to be reproduced by headphones or earphones, a spatial sound is created that creates a realistic sound impression.

[0006] Virtual sound, also called virtual sound space (see [7]) or virtual auditory space, is an audio technique in which sounds presented through headphones appear to originate from any desired spatial direction, creating the illusion of one or more virtual sound sources outside the listener's head.

[0007] A head-related transfer function (HRTF) is an acoustic transfer function from a sound source to the two ears. An HRTF contains the location information of the corresponding sound source. A virtual sound from a particular direction can be generated by convolution of the corresponding HRTF with the audio signal when heard through headphones.

[0008] To render spatial sound binaurally, the HRTFs of relevant positions around the listener are measured and stored. HRTFs are frequency dependent and provide the essential psychoacoustic cues for a plausible binaural effect.

[0009] For example, when using speaker boxes instead of headphones to play binaural audio signals, the signal played by one of the speaker boxes reaches both ears, thus generating crosstalk. In order to correctly play back the binaural signal through a pair of speakers, this signal should be pre-filtered to compensate for the crosstalk effect, which significantly impairs the spatial characteristics of the binaural signal, e.g. crosstalk cancellation (CTC) applied before playback shall avoid or at least reduce the crosstalk.

[0010] To achieve crosstalk cancellation, the applied filter matrices introduce spectral distortions, which may be due, for example, to extreme dynamics in the phase / magnitude response of the filters. For example, the spectral dynamics of the crosstalk cancellation filter matrices may reach extreme values ​​in certain frequency bands. This affects the overall timbre, especially the intelligibility, the presence of central source timbre, and the perceived quality of the crosstalk cancellation based playback system.

[0011] The concept of crosstalk cancellation is described in [1] and [2]. TIFF2025506064000103.tif1032 is a signal from two speakers. TIFF2025506064000104.tif1222 shows the transfer function when replayed by two speaker boxes.

[0012] Listener's left ear TIFF2025506064000105.tif44 and right ear The two signals in TIFF2025506064000106.tif45 can be expressed as follows: TIFF2025506064000107.tif1056 signal TIFF2025506064000108.tif45 is the first speaker The signal is fed to the first speaker box (e.g., the left speaker) with TIFF2025506064000109.tif43. TIFF2025506064000110.tif45 is the second speaker TIFF2025506064000111.tif43 is fed to a second speaker box (e.g., Right Speaker).

[0013] signal TIFF2025506064000112.tif44 is a first signal received at a listener's first ear (e.g., the listener's left ear). TIFF2025506064000113.tif45 is a second signal received at the listener's second ear (eg, the listener's right ear).

[0014] First speaker For TIFF2025506064000114.tif43 (e.g. left speaker), crosstalk coefficient TIFF2025506064000115.tif69 is the speaker mentioned above. TIFF2025506064000116.tif43 showing direct path and crosstalk coefficients TIFF2025506064000117.tif69 is the speaker mentioned above. Shows the cross-path of TIFF2025506064000118.tif43.

[0015] Second Speaker For TIFF2025506064000119.tif43 (e.g. right speaker), crosstalk coefficient TIFF2025506064000120.tif610 is the speaker mentioned above. TIFF2025506064000121.tif43 showing direct path and crosstalk coefficients TIFF2025506064000122.tif69 is the speaker mentioned above. Shows the cross-path of TIFF2025506064000123.tif43.

[0016] therefore, TIFF2025506064000124.tif44 describes the correction of the loudspeaker signal to the ipsilateral ear and the crosstalk to the contralateral ear (see [1], [2]). In TIFF2025506064000125.tif44, the coefficient TIFF2025506064000126.tif58 and TIFF2025506064000127.tif58 shows the crosstalk components that should be canceled or at least reduced.

[0017] Before the audio signal is output by the two speakers, two crosstalk-canceled speaker signals are To obtain TIFF2025506064000128.tif1368, the filter matrix C is used to filter the audio signals for the two speakers. TIFF2025506064000129.tif45, When applied to TIFF2025506064000130.tif45, perfect reconstruction of the signal at the listener's ears, i.e. perfect crosstalk cancellation, is achieved. It is obtained by inverting the HRTF matrix H according to TIFF2025506064000131.tif1060, where TIFF2025506064000132.tif44 is Given by TIFF2025506064000133.tif449. Figure 2 shows a schema for such a two-channel crosstalk cancellation system.

[0018] A perfect crosstalk cancellation system would introduce perfect separation of the ear signals without introducing any additional coloration into the binauralized source signals, i.e., when the listener is positioned in the sweet spot. However, in real-world crosstalk cancellation systems, unwanted coloration is generally unavoidable.

[0019] One important factor affecting the spectral distortion is the CTC coefficients in C. Inversion of the matrix H is likely to be an undesirable problem. To achieve sufficient crosstalk cancellation performance, the CTC filter matrix may exhibit extreme spectral dynamics in certain frequency bands.

[0020] In prior art approaches, the dynamics of the filter matrix C is reduced by (frequency-dependent) regularization of the inverse problem (see [3]).

[0021] FIG. 3 shows an example transfer function matrix H, assuming symmetric HRTFs and a total speaker opening angle of 30°.

[0022] FIG. 4 shows an example transfer function matrix C(H) with low regularization applied, where The file is TIFF2025506064000134.tif418.

[0023] FIG. 5 shows an example transfer function matrix C(H) with increased regularization applied, where The file is TIFF2025506064000135.tif417.

[0024] Consider the example of a virtual center component: summation of the direct and crosstalk signals on a single system loudspeaker can cause coloration and reduce their presence (see [4]). Since the input signals to both system channels are correlated, the coloration expected in this case differs from other cases, such as ambient components, where the crosstalk cancelling filters are orthogonal to each other.

[0025] Some approaches apply dynamic adaptation of the crosstalk cancellation signal.

[0026] Some prior art approaches appear to propose pre-processing of the input signal. In US Patent No. 9 532 156 (see [5]) an apparatus and method for audio stage enhancement is provided. A spatial ratio is determined from the center and side components. The digital audio input signal is adjusted based on the spatial ratio to form a pre-processed signal. The center component of the crosstalk cancellation signal is re-adjusted to generate the final digital audio output.

[0027] In US Patent No. 10 063 984 (see [6]) a method is presented for creating a virtual acoustic stereo system with a distortion-free acoustic center. A medial / lateral separation of the CTC input signal is performed in order to apply crosstalk cancellation only to the lateral components and not to distort the medial components. [Prior art documents] [Patent documents]

[0028] [Patent Document 1] U.S. Patent No. 9 532 156 [Patent Document 2] US Patent No. 10 063 984 Summary of the Invention [Problem to be solved by the invention]

[0029] It is an object of the present invention to provide an improved concept for reducing spectral distortions in a system for reproducing virtual sounds. [Means for solving the problem]

[0030] The object of the present invention is solved by an apparatus according to claim 1, a system according to claim 29, a method according to claim 34 and a computer program according to claim 35.

[0031] An apparatus is provided for reducing spectral distortion in a system for reproducing virtual sound through loudspeakers, the apparatus being configured to reduce the spectral distortion by performing adaptive equalization and / or by performing time dynamic equalization.

[0032] Further provided is a system for reproducing virtual sounds via speakers, the system comprising a speaker signal generator for generating two or more audio output signals from one or more audio input signals, the system further comprising an apparatus for reducing spectral distortion as described above, the apparatus being configured to reduce the spectral distortion by performing adaptive equalization and / or time dynamic equalization on at least one of the one or more audio input signals and / or on at least one of the two or more audio output signals and / or on filter information used by the speaker signal generator on the one or more audio input signals or on one or more processed signals dependent on the one or more audio input signals.

[0033] Further provided is a method for reducing spectral distortion in a system for reproducing virtual sounds through loudspeakers, the method comprising reducing the spectral distortion by performing adaptive equalization and / or by performing time dynamic equalization.

[0034] Furthermore, a computer program is provided for carrying out the above-described method when executed on a computer or signal processor.

[0035] Some embodiments aimed at countering spectral distortions may apply signal component specific equalizers, for example to components of the input signal or the crosstalk cancelled speaker signals, to reduce signal coloration while preserving the acquired virtual spatial image at the designated listening position.

[0036] According to some embodiments, it is intended to reduce the spectral distortion through the virtual sound stereo system by jointly equalizing the two speaker signals depending on the applied crosstalk cancellation filters and similarity information of the crosstalk cancellation signals.

[0037] In order to reduce expected spectral distortions while preserving the intended virtual spatial image, according to one embodiment, a correction filter is applied for each output signal frame, which can be derived in advance, for example, from a sum of crosstalk correlation filter matrices. In some embodiments, it can be assumed that different signal components, such as, for example, center, surrounding, and side components, require different correction filters. In some embodiments, a combination of correction filter sets can be determined, for example, and applied depending on the output signal. An advantage is that the applied correction equalizer can be adjusted to improve the timbre of a particular component of the input signal.

[0038] Some embodiments aim to reduce the tonal distortion to an acceptable level while preserving the CTC performance, e.g. "spatial effect", as good as possible. In some embodiments, a dynamic equalizer (CTC-DynEQ) is used to adjust the overall tonal distortion of the processed signal of the two channels, which can operate, e.g. in the QMF domain, e.g. on a per-buffer basis, and can be, e.g., user adjustable.

[0039] In one embodiment, the dynamic equalizer may act on the output signal, for example, by compensating to a variable degree for the expected level of coloration, which may be approximated, for example, by simulating a sum of active CTC filters in the output speaker path.

[0040] According to one embodiment, a set of compensation equalizer magnitude responses can be generated, for example, depending on the expected coloration of three basic cases: center equalizer (EQ), side EQ, and surround EQ.

[0041] In one embodiment, the compensation filter applied may be, for example, user adjustable.

[0042] According to an embodiment, the compensation filter applied may for example be obtained from a combination of these equalizers, for example as a function of an inter-channel similarity metric that may be derived from the processed signal. In an embodiment, for example, weighting of the equalizer components may be performed before and / or during the combination of these equalizers.

[0043] Some embodiments provide dynamic equalization for crosstalk cancellation.

[0044] According to some embodiments, the input signal is taken into account.

[0045] In some embodiments, timbre correction is applied during runtime depending on the input signal components, with the timbre emphasis being specifically tailored to the virtual centre signal component, whereas ambient signals may, for example, be corrected differently.

[0046] According to an embodiment, application of equalization to the input signal and / or the output signal and / or to the crosstalk cancellation filter matrix may for example be performed.

[0047] In one embodiment, the equalization may be determined, for example, by performing a calculation based on the crosstalk cancellation coefficients.

[0048] According to one embodiment, the calculation of the equalizer components may be performed, for example, based on a combination of complex crosstalk cancellation coefficients in the frequency domain.

[0049] In one embodiment, for example, a linear combination of complex crosstalk cancellation coefficients may be used to calculate the equalizer components.

[0050] According to one embodiment, multiple equalizer components for a single correction equalizer may be combined, for example.

[0051] In one embodiment, the equalizer components may be weighted, for example, before combination into a single correction equalizer.

[0052] According to one embodiment, the combination of equalizer components may be updated at a particular time based on, for example, one or more particular characteristics of the signal.

[0053] In one embodiment, the equalizer may be updated in response to information regarding signal similarity, for example.

[0054] According to one embodiment, the equalizer may be updated, for example, depending on signal similarity in one or more frequency bands.

[0055] In one embodiment, the equalizer may be updated based on, for example, the average similarity of multiple frequency bands.

[0056] According to one embodiment, for example, additional weighting may be used before calculating the average.

[0057] In one embodiment, for example, magnitude-based weighting may be used.

[0058] According to one embodiment, the components derived from the signal similarity may be weighted, for example, with a particular weighting function.

[0059] In one embodiment, for example, a sigmoid function may be used as the weighting function.

[0060] According to one embodiment, the magnitude of the frequency bands may be used, for example, to detect the frequency bands that are used to calculate similarity information.

[0061] In one embodiment, a certain number of frequency bands with the greatest magnitude may be used to calculate the similarity information, for example.

[0062] Some embodiments relate to head-related transfer functions and / or crosstalk cancellation filter matrices, for example for two speakers, for example in a mobile device.

[0063] In some embodiments, it is aimed to achieve reduced spectral distortion and / or reduced tonal distortion. According to some embodiments, for example, post-processing of the crosstalk cancelled signal can be performed.

[0064] Signal similarity and / or filter size of the crosstalk cancelled signal based on the addition of crosstalk cancellation coefficients can be determined, for example. Equalization of the middle, side surrounding signals can be provided, for example, to achieve distortion-free center for crosstalk cancellation and / or center enhancement for crosstalk cancellation, for example, by using dynamic equalization.

[0065] In the following, embodiments of the invention are explained in more detail with reference to the drawings. [Brief description of the drawings]

[0066] [Figure 1a] FIG. 1 illustrates an apparatus for reducing spectral distortion according to one embodiment. [Figure 1b] FIG. 1b shows an embodiment in which the device of FIG. 1a interacts with a system for playing virtual sounds through speakers, but the device of FIG. 1a is not part of the system. [Figure 1c] FIG. 1b shows a system for playing virtual sounds through speakers according to one embodiment, the system including the device of FIG. 1a. [Diagram 2] FIG. 1 illustrates a schema for a two-channel crosstalk cancellation system. [Diagram 3] FIG. 13 is a diagram of an exemplary transfer function matrix assuming symmetric head-related transfer functions. [Figure 4] FIG. 2 illustrates an example transfer function matrix with low regularization applied. [Diagram 5] FIG. 1 illustrates an example transfer function matrix with increased regularization applied. [Figure 6] FIG. 2 illustrates the generation of a central equalizer according to one embodiment. [Figure 7] FIG. 1 illustrates the generation of a side equalizer according to an embodiment. [Figure 8] FIG. 2 illustrates the generation of an ambient equalizer according to one embodiment. [Figure 9] FIG. 2 illustrates a sigmoid activation function according to one embodiment. [Figure 10] FIG. 13 illustrates an example of a resulting equalizer according to one embodiment. [Figure 11] FIG. 1 illustrates an average gain across all subbands introduced by an exemplary dynamic equalizer according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] FIG. 1a illustrates an apparatus 100 for reducing spectral distortion in a system 200 for reproducing virtual sounds via speakers according to an embodiment.

[0068] The apparatus 100 is configured to reduce spectral distortion by performing adaptive equalization and / or by performing time dynamic equalization.

[0069] Fig. 1b shows an embodiment in which the apparatus for reducing spectral distortion 100 of Fig. 1a and a system for reproducing virtual sounds via speakers 200 interact with each other, but the apparatus 100 of Fig. 1a is not part of the system 200. In other words, in the embodiment of Fig. 1b, the system 200 does not include the apparatus 100.

[0070] Fig. 1c shows a system 200 for playing virtual sounds through speakers according to one embodiment. In contrast to the embodiment of Fig. 1b, in the embodiment of Fig. 1c, the device 100 of Fig. 1a is part of the system 200. In other words, in the embodiment of Fig. 1c, the system 200 includes the device 100.

[0071] The following specific embodiments relate to the embodiment of FIG. 1a, and to the embodiment of FIG. 1b, and to the embodiment of FIG. 1c.

[0072] According to an embodiment, the apparatus 100 may be configured to reduce spectral distortions, for example by performing adaptive equalization and / or time dynamic equalization on at least one of the one or more audio input signals of the system 200 for reproducing virtual sounds and / or on at least one of two or more audio output signals of the system 200 and / or on filter information applied by the system 200 to the one or more audio input signals or to one or more processed signals dependent on the one or more audio input signals.

[0073] In an embodiment, the apparatus 100 may be configured to determine equalization information dependent on at least two of the audio input signals and / or dependent on at least two of the audio output signals and / or dependent on at least two of the processed signals. The apparatus 100 may be configured, for example, to perform adaptive equalization and / or by performing time dynamic equalization by using the equalization information.

[0074] According to one embodiment, the system 200 for reproducing virtual sound comprises a crosstalk cancellation system 200 for performing crosstalk cancellation to eliminate and / or reduce and / or avoid crosstalk generated by the system 200 when reproducing the virtual sound through speakers. The apparatus 100 is configured, for example, to reduce spectral distortions resulting from performing crosstalk cancellation.

[0075] In one embodiment, the apparatus 100 includes an equalizer. The apparatus 100 may be configured to update the equalizer at certain times, for example.

[0076] According to an embodiment, the apparatus 100 may be configured to determine the similarity information, for example, by determining information regarding the similarity of the at least two audio signals. The apparatus 100 may be configured to perform adaptive equalization and / or time dynamic equalization, for example, using the similarity information. Furthermore, one or more audio input signals of the system 200 may include at least two audio signals, two or more audio output signals of the system 200 may include at least two audio signals, or one or more processed signals may include at least two audio signals.

[0077] In one embodiment, to determine the similarity information, the apparatus 100 may be configured to, for example, determine information regarding a similarity of at least two audio signals in each of one or more frequency bands. The apparatus 100 may be configured to, for example, perform adaptive equalization and / or time dynamic equalization by using the information regarding the similarity of the signals in each of the one or more frequency bands.

[0078] According to an embodiment, to determine the similarity information, the apparatus 100 may be configured to, for example, determine an average of the similarities of at least two audio signals in each of a plurality of frequency bands. The apparatus 100 may be configured to perform adaptive equalization and / or time-dynamic equalization, for example by using the average of the similarities of the signals in each of a plurality of frequency bands.

[0079] In one embodiment, to determine the similarity information, the apparatus 100 may be configured to determine a magnitude-based weighted similarity by performing a magnitude-based weighting of the similarities of the at least two audio signals in each of a plurality of frequency bands. The apparatus 100 may be configured to perform adaptive equalization and / or time-dynamic equalization, for example, by using the magnitude-based weighted similarity.

[0080] According to one embodiment, the apparatus 100 may be configured to perform magnitude-based weighting, for example, by using a weighting function.

[0081] In one embodiment, the weighting function may be, for example, a sigmoid function.

[0082] According to an embodiment, the apparatus 100 may be configured to determine a suitable subset of one or more frequency bands from the plurality of frequency bands, for example, by using a magnitude of each of the plurality of frequency bands of the at least two audio signals to determine the suitable subset. The apparatus 100 may be configured to determine similarity information by determining similarity information for each of the one or more frequency bands of the suitable subset, for example, without determining similarity information for each of the one or more frequency bands of the plurality of frequency bands that are not included in the suitable subset.

[0083] In one embodiment, each frequency of the plurality of frequency bands may be associated with a magnitude that is dependent on the magnitude of one or more frequency bands of the at least two audio signals, for example. Apparatus 100 may be configured to determine a proper subset of the one or more frequency bands such that, for example, a magnitude associated with each frequency band of the one or more frequency bands of the proper subset may be greater than or equal to a magnitude associated with each of the one or more frequency bands of the plurality of frequency bands not included in the proper subset.

[0084] According to an embodiment, the system 200 for reproducing virtual sound may be configured to perform crosstalk cancellation, for example, by using a plurality of crosstalk cancellation coefficients. The device 100 may be configured to reduce spectral distortion, for example, by performing adaptive equalization using a plurality of equalizer components and / or by performing time dynamic equalization. The device 100 may be configured to determine the plurality of equalizer components depending on one or more of the plurality of crosstalk cancellation coefficients.

[0085] In one embodiment, the apparatus 100 may be configured to determine the plurality of equalizer components, for example, by selecting a set of pre-calculated equalizer components from a set of two or more pre-calculated equalizer components as a function of the crosstalk cancellation coefficients.

[0086] In one embodiment, the apparatus 100 may be configured to determine multiple equalizer components at run time, for example, in response to similarity information indicative of information regarding the similarity of at least two audio signals and / or in response to multiple crosstalk cancellation coefficients.

[0087] According to one embodiment, the apparatus 100 may be configured to determine the equalizer components by determining one or more combinations of crosstalk cancellation coefficients, e.g., complex crosstalk cancellation coefficients in the frequency domain.

[0088] In one embodiment, to determine one or more combinations of multiple crosstalk cancellation coefficients to determine the multiple equalizer components, the apparatus 100 may be configured to determine, for example, one or more linear combinations of complex crosstalk cancellation coefficients in the frequency domain.

[0089] According to one embodiment, the apparatus 100 may, for example, be configured to determine a single correction equalizer from multiple equalizer components.

[0090] In one embodiment, the apparatus 100 may be configured to determine a single correction equalizer from the multiple equalizer components, for example, by weighting the multiple equalizer components before combining them to obtain a single correction equalizer.

[0091] According to an embodiment, the apparatus 100 may be configured to, for example, weight a number of equalizer components depending on a similarity value, the similarity value being dependent on the similarity information.

[0092] In one embodiment, the apparatus 100 may be configured to perform adaptive equalization and / or time-dynamic equalization on one or more audio input signals of the system 200, for example to reproduce a virtual sound.

[0093] According to one embodiment, the apparatus 100 may be configured to perform adaptive equalization and / or time dynamic equalization on two or more audio output signals of the system 200, for example to reproduce a virtual sound.

[0094] In one embodiment, the apparatus 100 may be configured, for example, to perform adaptive equalization and / or by performing time dynamic equalization on crosstalk cancellation filter matrices used for crosstalk cancellation by the system for reproducing virtual sound (200).

[0095] FIG. 1c illustrates a system 200 for playing virtual sounds through speakers, according to one embodiment.

[0096] The system 200 of FIG. 1c includes a speaker signal generator 150 that generates two or more audio output signals from one or more audio input signals.

[0097] Furthermore, the system 200 of FIG. 1c comprises the apparatus 100 of FIG. 1a for reducing spectral distortion.

[0098] In the system 200 of FIG. 1c, the apparatus 100 is configured to reduce spectral distortions by performing adaptive equalization and / or time dynamic equalization on at least one of the one or more audio input signals and / or on at least one of the two or more audio output signals and / or on filter information used by the speaker signal generator 150 on the one or more audio input signals or on one or more processed signals that are dependent on the one or more audio input signals.

[0099] According to an embodiment, the system 200 for reproducing virtual sound may comprise a crosstalk cancellation system (not shown) for performing crosstalk cancellation, for example to eliminate and / or reduce and / or avoid crosstalk generated by the system for performing crosstalk cancellation when reproducing the virtual sound via speakers. The apparatus 100 is configured, for example, to reduce spectral distortion resulting from performing crosstalk cancellation.

[0100] In one embodiment, the one or more audio input signals may include, for example, two binaural audio signals.

[0101] According to one embodiment, the system 200 of Fig. 1c includes, for example, a speaker. In another embodiment, the system of Fig. 1c does not include, for example, a speaker.

[0102] In one embodiment, apparatus 100 may be configured to perform adaptive equalization, e.g., by applying an average gain across two or more subbands, e.g., to achieve loudness preservation, and / or to perform time-dynamic equalization. In a particular embodiment, apparatus 100 may be configured to apply an average gain across all subbands, e.g.

[0103] Specific embodiments of the present invention are described below. In an embodiment, a correction equalizer can be applied, for example, in the QMF domain, to the crosstalk-canceled speaker signals, for example, to combat expected coloration. According to an embodiment, the correction filter can be determined / estimated, for example, for the expected magnitude response in the case of, for example, three fundamental signal components, by a summation depending on a complex CTC filter matrix, for example three.

[0104] For example, for the middle component, the middle / center equalizer ( TIFF2025506064000136.tif513 / TIFF2025506064000137.tif517 r ) may be determined, for example, and / or, for example, in the case of the side components, a side equalizer ( TIFF2025506064000138.tif513) may be determined, for example. And / or, for example, in the case of the ambient component, an ambient equalizer ( TIFF2025506064000139.tif514) may, for example, be determined. For example, the terms median equalizer and center equalizer may, for example, be used interchangeably.

[0105] According to one embodiment, a combination of three component equalizers can determine, for example, the equalizer to be applied, which may depend, for example, on signal similarity information about the output signal and / or may depend, for example, on manual adjustment of component weights.

[0106] The determination of the component equalizers according to some embodiments is described below. According to some embodiments, two or more, e.g., three, component equalizers (also referred to as equalizer components) may be determined, for example. The determination of the three component equalizers may be performed, for example, prior to runtime. For example, the component equalizers may be determined, for example, as described below.

[0107] Some embodiments are TIFF2025506064000140.tif48( Phase difference between channels for each TIFF2025506064000141.tif43 ( TIFF2025506064000142.tif48) the expected coloration of a two-channel input signal s with, for example, speaker index QMF bandwidth in TIFF2025506064000143.tif45 Resulting amplitude spectrum per TIFF2025506064000144.tif43 This is based on the finding that the direct path for each speaker can be estimated based on TIFF2025506064000145.tif613. TIFF2025506064000146.tif510 and cross-path Depends on the sum of CTC filters in TIFF2025506064000147.tif510. TIFF2025506064000148.tif676

[0108] Center Equalizer The magnitude response of TIFF2025506064000149.tif517 is, for example, the IPD across all bands (e.g., phantom center image), averaged across both loudspeakers. center (b) Two-channel input signal with s = 0° center It is possible to compensate for the expected coloration of the

[0109] Side Equalizer The magnitude response of TIFF2025506064000150.tif513 is averaged across both speakers, for example: IPD side (b) Two-channel input signal s with =180° side It is possible to compensate for the expected coloration of the

[0110] Ambient Equalizer In the case of TIFF2025506064000151.tif514, the left and right input signals may for example be uncorrelated. The average expected coloration per speaker may for example assume unit power in the input spectrum. TIFF2025506064000152.tif1579TIFF2025506064000153.tif1575TIFF2025506064000154.tif2287In the above formula, i may represent, for example, a speaker index: i=sp.

[0111] In the following, taking into account the similarity of speaker signals according to some embodiments will be described.

[0112] In some embodiments, the speaker signal similarity may be obtained / determined, for example, for each input buffer. For example, the speaker signal similarity may be obtained, for example, during run-time.

[0113] To modulate the frequency response of the resulting compensation equalizer, according to one embodiment, the similarity vector For example, TIFF2025506064000155.tif512 is It can be derived for TIFF2025506064000156.tif32. TIFF2025506064000157.tif615 and TIFF2025506064000158.tif615 may, for example, represent a two-channel complex-valued signal for each buffer and frequency band.

[0114] TIFF2025506064000159.tif511 is, for example, Similarity metric for bands 0 and 1, weighted by TIFF2025506064000160.tif517 It is possible to show a combination of TIFF2025506064000161.tif513. The sigmoid function in TIFF2025506064000162.tif512 is center ,s side ) to the advantage of The intention is to tilt the values ​​in TIFF2025506064000163.tif511.

[0115] In one embodiment, the first two frequency bands ( TIFF2025506064000164.tif43=0,1) amplitudes can be considered, for example. However, in another preferred embodiment, first the two QMF bands with the largest magnitudes can be determined, for example, and selected, for example, for signal similarity estimation and weighting instead, which improves stability.

[0116] Similarity Vector To stabilize TIFF2025506064000165.tif511, for example, a weighting factor that introduces relative weights between inter-channel similarity values. TIFF2025506064000166.tif517 can be used. It may depend, for example, on the distribution of input levels between the two QMF bands across the input channels. A low signal amplitude in one frequency band may, for example, have a disproportionate effect on the resulting similarity vector. If, for example, useful signals are only present in QMF band 1 and band 2 consists only of a low amplitude noise floor, the resulting similarity values ​​may show unpredictable behavior between adjacent input buffers.

[0117] TIFF2025506064000167.tif412 has a slightly reduced range of possible values ​​and can be adjusted between 0 and 1. TIFF2025506064000168.tif1247TIFF2025506064000169.tif869TIFF2025506064000170.tif32170Or, for example, TIFF2025506064000171.tif13114

[0118] In the following, it is described how the resulting equalization is obtained by combining similarity vectors and / or manual adjustment coefficients according to some embodiments.

[0119] According to certain embodiments, the magnitude of the applied equalizer, e.g., a dynamic equalizer, TIFF2025506064000172.tif519 or TIFF2025506064000173.tif523 is, for example, the ambient equalizer Side Equalizer for TIFF2025506064000174.tif519 TIFF2025506064000175.tif519 or Center Equalizer It can be combined with either TIFF2025506064000176.tif523. Coefficients TIFF2025506064000177.tif413, TIFF2025506064000178.tif49, and TIFF2025506064000179.tif49 may, for example, be calculated once per input buffer. They may, for example, be calculated as similarity vectors TIFF2025506064000180.tif56 and / or adjustment parameters TIFF2025506064000181.tif524 and / or TIFF2025506064000182.tif521 and / or TIFF2025506064000183.tif521, which may be a user-adjustable tuning parameter, for example ranging from 0 to 1. The relative weighting of the equalizer components may be adjustable, for example to balance the spatial and temporal impression of the system. TIFF2025506064000184.tif44120TIFF2025506064000185.tif6114TIFF2025506064000186.tif6122

[0120] for example, TIFF2025506064000187.tif513, for example TIFF2025506064000188.tif533, which would result in the following: TIFF2025506064000189.tif6124

[0121] According to an embodiment, the resulting equalizer may be applied to the output speaker signal, for example.

[0122] 6 through 11 visually illustrate examples of the embodiments provided. 6 is a diagram illustrating the generation of a central equalizer (EQ) according to one embodiment, where the x-axis labels indicate the center frequencies of the QMF bands. FIG. 7 is a diagram illustrating the generation of a side equalizer according to one embodiment. FIG. 8 is a diagram illustrating the generation of an ambient equalizer according to one embodiment.

[0123] FIG. 9 illustrates a sigmoid activation function with a signal similarity value of −0.5 and a weight of 0.4 according to one embodiment. 10 illustrates an example of a resulting equalizer according to one embodiment. The ambient EQ is labeled "EQ 90." FIG. 11 illustrates an average gain across all subbands introduced by an exemplary dynamic equalizer (DynEQ) according to one embodiment.

[0124] The inventive concept may for example be used in other domains, for example other frequency domains, for example the FFT domain instead of the QMF domain. Some embodiments may for example be implemented in the Fast Fourier Transform (FFT) domain.

[0125] In one embodiment, the selection of the QMF bands may be used, for example, for signal similarity estimation. In one implementation (e.g., headphone library headphonelib), speaker signal similarity may be based, for example, on the two bands with the largest magnitude. This allows for stability when, for example, signal energy in bands 0 and 1 is low.

[0126] According to an embodiment, the device 100 may be configured to reduce spectral distortions, for example, by performing adaptive equalization in a loudness-preserving manner and / or by performing time-dynamic equalization in a loudness-preserving manner and / or by adjusting one or more audio input signals to ensure loudness preservation. For example, loudness preservation may be ensured, for example, by an applied equalizer. This may be countered by applying a component or applied equalizer and / or a make-up gain factor to the signal, such that the average or root-mean-square (RMS) volume of the output signal is not affected.

[0127] In an embodiment, for example, a different configuration for the component equalizer magnitude response may be used. The above approach for estimating the magnitude of the component correction filter may, for example, be modified. The variation may, for example, be related to the sum of the complex CTC filters, for example, by applying variable weighting to specific frequency regions. According to an embodiment, weighting between the direct and crosstalk components may, for example, be introduced to specifically address coloration by one component. In another embodiment, the equalizer components may, for example, be calculated at run-time.

[0128] According to one embodiment, for example, a (e.g., frequency selective) compression or expansion of the spectral dynamics for a particular frequency region of the components or applied filters can be used. According to another embodiment, the equalizer components may be calculated, for example, at run time.

[0129] In one embodiment, for example, different combinations of component equalizers can be applied. For example, a center equalizer (EQ center ) and Side Equalizer (EQ side The size of the EQ is, for example, amb ) may be summed to create a similarity (corrLR) between the left and right signals. In the intermediate case, for example, where the similarity (corrLR) between the left and right signals is +-0.5, it is not guaranteed that the applied equalizer will match well with the model of the assumed coloration. Variations and / or combinations of the component equalizers can be implemented in any suitable manner, for example. Complex summations of correction EQs can be performed.

[0130] According to one embodiment, for example, a constrained optimization approach can be used: the filters to be applied can be generated for each frequency band with respect to its signal similarity, taking into account, for example, the expected crosstalk cancellation in a sweet spot within this band. Further embodiments are provided below. Embodiment 1: An apparatus (100) for reducing spectral distortion in a system (200) for reproducing virtual sounds through speakers, comprising: An apparatus (100), wherein the apparatus (100) is configured to reduce spectral distortion by performing adaptive equalization and / or by performing time dynamic equalization. Embodiment 2: The apparatus (100) of embodiment 1, wherein the apparatus (100) is configured to reduce spectral distortion by performing adaptive equalization and / or time dynamic equalization on at least one of one or more audio input signals of a system (200) for reproducing virtual sound and / or on at least one of two or more audio output signals of the system (200) and / or on filter information applied by the system (200) to the one or more audio input signals or one or more processed signals dependent on the one or more audio input signals. Embodiment 3: An apparatus (100) configured to determine equalization information in dependence on at least two of the audio input signals and / or in dependence on at least two of the audio output signals and / or in dependence on at least two of the processed signals; 3. The apparatus (100) of embodiment 2, wherein the apparatus (100) is configured to perform adaptive equalization and / or to perform time dynamic equalization by using the equalization information. Embodiment 4: A system (200) for reproducing virtual sound comprises a crosstalk cancellation system (200) for performing crosstalk cancellation to eliminate and / or reduce and / or avoid crosstalk generated by the system (200) when reproducing the virtual sound through speakers, The apparatus (100) of any one of embodiments 2 to 3, wherein the apparatus (100) is configured to reduce spectral distortion resulting from performing crosstalk cancellation. Embodiment 5: The apparatus (100) comprises an equalizer, 5. The apparatus (100) of any one of embodiments 2 to 4, wherein the apparatus (100) is configured to update the equalizer at a particular time. Embodiment 6: An apparatus (100) configured to determine similarity information by determining information regarding the similarity of at least two audio signals, an apparatus (100) configured to perform adaptive equalization and / or time dynamic equalization using the similarity information; The apparatus (100) of any one of embodiments 2 to 5, wherein one or more audio input signals of the system (200) include at least two audio signals, two or more audio output signals of the system (200) include at least two audio signals, or one or more processed signals include at least two audio signals. Embodiment 7: For determining similarity information, an apparatus (100) is configured to determine information relating to similarity of at least two audio signals in each of one or more frequency bands, An apparatus (100) as described in embodiment 6, wherein the apparatus (100) is configured to perform adaptive equalization and / or time dynamic equalization by using information regarding the similarity of signals in each of one or more frequency bands. Embodiment 8: To determine the similarity information, the apparatus (100) is configured to determine an average of similarities of at least two audio signals in each of a plurality of frequency bands; The apparatus (100) of embodiment 6 or 7, wherein the apparatus (100) is configured to perform adaptive equalization and / or time dynamic equalization by using an average of the signal similarity in each of a plurality of frequency bands. Embodiment 9: To determine the similarity information, the apparatus (100) is configured to determine a magnitude-based weighted similarity by performing a magnitude-based weighting of the similarity of at least two audio signals in each of a plurality of frequency bands; The apparatus (100) of any one of embodiments 6 to 8, wherein the apparatus (100) is configured to perform adaptive equalization and / or time dynamic equalization by using magnitude-based weighted similarity. Embodiment 10: The apparatus (100) of embodiment 9, wherein the apparatus (100) is configured to perform magnitude-based weighting by using a weighting function. Embodiment 11: The apparatus (100) of embodiment 10, wherein the weighting function is a sigmoid function. Embodiment 12: The apparatus (100) of any one of embodiments 9 to 11, wherein the apparatus (100) is configured to perform magnitude-based weighting by using the magnitudes of multiple frequency bands to detect which of the multiple frequency bands to use to calculate similarity information. Embodiment 13: The apparatus (100) of any one of embodiments 9 to 12, wherein the apparatus (100) is configured to perform magnitude-based weighting by using a certain number of frequency bands with the largest magnitudes to calculate the similarity information.

[0023] Embodiment 14: An apparatus (100) configured to determine a suitable subset of one or more frequency bands from a plurality of frequency bands by using a magnitude of each of a plurality of frequency bands of at least two audio signals to determine the suitable subset; An apparatus (100) as described in any one of embodiments 6 to 13, wherein the apparatus (100) is configured to determine similarity information by determining similarity information for each of one or more frequency bands of a suitable subset without determining similarity information for each of one or more frequency bands of a plurality of frequency bands that are not included in the suitable subset. Embodiment 15: Each frequency of a plurality of frequency bands is associated with a magnitude that depends on the magnitude of one or more frequency bands of the at least two audio signals; An apparatus (100) as described in embodiment 14, wherein the apparatus (100) is configured to determine a suitable subset of one or more frequency bands such that a magnitude associated with each frequency band of the suitable subset is greater than or equal to a magnitude associated with each of one or more frequency bands of the plurality of frequency bands not included in the suitable subset. Embodiment 16: A system (200) for reproducing virtual sound is configured to perform crosstalk cancellation by using a plurality of crosstalk cancellation coefficients, The apparatus (100) is configured to reduce spectral distortion by performing adaptive equalization using a plurality of equalizer components and / or by performing time dynamic equalization; The apparatus (100) of any one of embodiments 1 to 15, wherein the apparatus (100) is configured to determine a plurality of equalizer components according to one or more of a plurality of crosstalk cancellation coefficients. Embodiment 17: The apparatus (100) of embodiment 16, wherein the apparatus (100) is configured to determine a plurality of equalizer components by selecting a set of pre-calculated equalizer components from a set of two or more pre-calculated equalizer components according to crosstalk cancellation coefficients. Embodiment 18: The device (100) of embodiment 16, further dependent on any one of embodiments 6 to 15, wherein the device (100) is configured to determine multiple equalizer components at run time in response to similarity information indicating information regarding the similarity of at least two audio signals and / or in response to multiple crosstalk cancellation coefficients. Embodiment 19: The apparatus (100) of embodiment 16 or 18, wherein the apparatus (100) is configured to determine a plurality of equalizer components by determining one or more combinations of a plurality of crosstalk cancellation coefficients, the combinations being a plurality of complex crosstalk cancellation coefficients in the frequency domain. Embodiment 20: The apparatus (100) of embodiment 19, wherein to determine one or more combinations of multiple crosstalk cancellation coefficients to determine multiple equalizer components, the apparatus (100) is configured to determine one or more linear combinations of complex crosstalk cancellation coefficients in the frequency domain. Embodiment 21: The apparatus (100) of embodiment 20, wherein the apparatus (100) is configured to determine a single correction equalizer from a plurality of equalizer components. Embodiment 22: The apparatus (100) of embodiment 21, wherein the apparatus (100) is configured to determine a single correction equalizer from the multiple equalizer components by weighting the multiple equalizer components before combining the multiple equalizer components to obtain a single correction equalizer. Embodiment 23: The apparatus (100) of embodiment 20, further dependent on any one of embodiments 6 to 15, wherein the apparatus (100) is configured to weight multiple equalizer components according to a similarity value, the similarity value depending on the similarity information. Embodiment 24: An apparatus (100) described in any one of embodiments 1 to 23, wherein the apparatus (100) is configured to perform adaptive equalization and / or time dynamic equalization on one or more audio input signals of the system (200) to reproduce virtual sound. Embodiment 25: An apparatus (100) described in any one of embodiments 3 to 24, further dependent on embodiment 2, wherein the apparatus (100) is configured to perform adaptive equalization and / or time dynamic equalization on two or more audio output signals of the system (200) to reproduce virtual sound. Embodiment 26: An apparatus (100) described in any one of embodiments 1 to 25, wherein the apparatus (100) is configured to perform adaptive equalization and / or time dynamic equalization on a crosstalk cancellation filter matrix used for crosstalk cancellation by the system (200) for reproducing virtual sound. Embodiment 27: An apparatus (100) described in any one of embodiments 3 to 26, further dependent on embodiment 2, wherein the apparatus (100) is configured to reduce spectral distortion by performing adaptive equalization in a manner that maintains volume, and / or by performing time dynamic equalization in a manner that maintains volume, and / or by adjusting one or more audio input signals to ensure that volume is maintained. Embodiment 28: The apparatus (100) of any one of embodiments 1 to 27, wherein the apparatus (100) is configured to perform adaptive equalization by applying an average gain across two or more subbands and / or to perform time dynamic equalization. Embodiment 29: A system (200) for reproducing virtual sounds through a speaker, the system (200) comprising: a speaker signal generator (150) for generating two or more audio output signals from one or more audio input signals; A system (200) comprising an apparatus (100) for reducing spectral distortion according to any one of embodiments 1 to 28, A system (200), wherein the apparatus (100) is configured to reduce spectral distortion by performing adaptive equalization and / or time dynamic equalization on at least one of one or more audio input signals and / or on at least one of two or more audio output signals and / or on filter information used by a speaker signal generator on the one or more audio input signals or on one or more processed signals dependent on the one or more audio input signals. Embodiment 30: A system (200) for reproducing virtual sound comprises a crosstalk cancellation system for performing crosstalk cancellation to eliminate and / or reduce and / or avoid crosstalk generated by the crosstalk cancellation system when reproducing the virtual sound through a loudspeaker, 30. The system (200) of embodiment 29, wherein the apparatus (100) is configured to reduce spectral distortion resulting from crosstalk cancellation. Embodiment 31: The system (200) described in embodiment 30, wherein the one or more audio input signals include two binaural audio signals. Embodiment 32: A system (200) described in any one of embodiments 29 to 31, wherein the system (200) does not include a speaker. Embodiment 33: A system (200) described in any one of embodiments 29 to 31, wherein the system (200) is equipped with a speaker. Embodiment 34: A method for reducing spectral distortion in a system (200) for reproducing virtual sounds through speakers, comprising: A method, the method including reducing spectral distortion by performing adaptive equalization and / or by performing time dynamic equalization. Embodiment 35: A computer program for carrying out the method according to embodiment 34, when the computer program is run on a computer or signal processor.

[0131] Although some aspects have been described in the context of an apparatus, it will be apparent that these aspects also represent a description of a corresponding method, where a block or device corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

[0132] Depending on the specific implementation requirements, embodiments of the present invention can be implemented in hardware or software, or at least partly in hardware, or at least partly in software. The implementation can be performed using a digital storage medium, such as a floppy disk, DVD, Blu-Ray, CD, ROM, PROM, EPROM, EEPROM or flash memory, on which electronically readable control signals are stored, which cooperate (or can cooperate) with a programmable computer system to execute the respective method. The digital storage medium may therefore be computer readable.

[0133] Some embodiments according to the invention include a data carrier having electronically readable control signals capable of cooperating with a programmable computer system to cause one of the methods described herein to be performed.

[0134] Generally, embodiments of the present invention can be implemented as a computer program product having program code that operates to perform one of the methods when the computer program product is run on a computer. The program code can, for example, be stored on a machine readable carrier.

[0135] Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier.

[0136] In other words, therefore, an embodiment of the inventive methods is a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.

[0137] A further embodiment of the inventive method is therefore a data carrier (or digital storage medium, or computer readable medium) having recorded thereon a computer program for performing one of the methods described herein. The data carrier, digital storage medium, or recording medium is typically tangible and / or non-transitory.

[0138] A further embodiment of the inventive method is therefore a data stream or a sequence of signals representing the computer program for performing one of the methods described herein, The data stream or the sequence of signals can for example be arranged to be transferred via a data communication connection, for example via the Internet.

[0139] A further embodiment comprises a processing means, for example a computer, or a programmable logic device, configured to or adapted to perform one of the methods described herein.

[0140] A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.

[0141] Further embodiments according to the invention comprise an apparatus or a system arranged to transfer (e.g. electronically or optically) a computer program for performing one of the methods described herein to a receiver. The receiver may for example be a computer, a mobile device, a memory device, etc. The apparatus or system may for example comprise a file server for transferring the computer program to the receiver.

[0142] In some embodiments, a programmable logic device (e.g., a field programmable gate array) may be used to perform some or all of the functions 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, the methods are preferably performed by any hardware apparatus.

[0143] The apparatus described herein may be implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0144] The methods described herein may be performed using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0145] The above-described embodiments are merely illustrative of the principles of the present disclosure. It is understood that modifications and variations of the arrangements and details described herein will be apparent to those skilled in the art. It is therefore intended to be limited only by the scope of the appended claims and not by the specific details presented as descriptions and explanations of the embodiments herein.

[0146] literature [1] Masiero, B., Fels, J., & Vorlaender, M. (2011).Review of the crosstalk cancellation filter technique.Proc. of ICSA, 112. [2] Kaiser, F.(2011).Transaural Audio-The reproduction of binaural signals over loudspeakers (Doctoral dissertation, Diploma Thesis, Universitaet fuer Musik und darstellende Kunst Graz / Institut fuer Elekronische Musik und Akustik / IRCAM, March 2011). [3] Choueiri, E.Y.(2008).Optimal crosstalk cancellation for binaural audio with two loudspeakers.Princeton University, 28. [4] Canfield, G.H., & Kuo, S.M.(1997, September).Dual-Channel Audio Equalization and Cross-Talk Cancellation for Correlated Stereo Signals.In Audio Engineering Society Convention 103.Audio Engineering Society. [5] US 9 532 156 B2, Apparatus and Method for Sound Stage Enhancement. [6] US 10 063 984 B2, Method for creating a virtual acoustic stereo system (200) with an undistorted acoustic center. [7] https: / / en.wikipedia.org / wiki / Acoustic_space .

Claims

1. An apparatus (100) for reducing spectral distortion in a system (200) for reproducing virtual sounds through speakers, comprising: the apparatus (100) is configured to reduce the spectral distortion by performing adaptive equalization and / or by performing time dynamic equalization, Apparatus (100).

2. the device (100) is configured to reduce the spectral distortion by performing the adaptive equalization and / or the time dynamic equalization on at least one of one or more audio input signals of the system (200) for reproducing virtual sounds and / or on at least one of two or more audio output signals of the system (200) and / or on filter information applied by the system (200) to the one or more audio input signals or to one or more processed signals dependent on the one or more audio input signals, The apparatus (100) of claim 1.

3. the apparatus (100) is configured to determine equalization information in dependence on at least two of the audio input signals, and / or in dependence on at least two of the audio output signals, and / or in dependence on at least two of the processed signals, the apparatus (100) is configured to perform the adaptive equalization and / or to perform the time dynamic equalization by using the equalization information. The apparatus (100) of claim 2.

4. said system (200) for reproducing virtual sound comprises a crosstalk cancellation system (200) for performing crosstalk cancellation to remove and / or reduce and / or avoid crosstalk generated by said system (200) when reproducing said virtual sound through said loudspeakers, the apparatus (100) is configured to reduce spectral distortion resulting from performing the crosstalk cancellation.

4. Apparatus (100) according to claim 2 or 3.

5. The device (100) comprises an equalizer; The apparatus (100) is configured to update the equalizer at a particular time. An apparatus (100) according to any one of claims 2 to 4.

6. the apparatus (100) is configured to determine similarity information by determining information regarding the similarity of at least two audio signals, the apparatus (100) is configured to use the similarity information to perform the adaptive equalization and / or the time dynamic equalization, the one or more audio input signals of the system (200) comprise the at least two audio signals, the two or more audio output signals of the system (200) comprise the at least two audio signals, or the one or more processed signals comprise the at least two audio signals; An apparatus (100) according to any one of claims 2 to 5.

7. To determine the similarity information, the apparatus (100) is configured to determine information regarding a similarity of at least two audio signals in each of one or more frequency bands, the device (100) is configured to perform the adaptive equalization and / or the time dynamic equalization by using the information on the similarity of the signals in each of the one or more frequency bands.

7. The apparatus (100) of claim 6.

8. To determine the similarity information, the apparatus (100) is configured to determine an average of similarities of at least two audio signals in each of a plurality of frequency bands; the device (100) is configured to perform the adaptive equalization and / or the time dynamic equalization by using an average of the similarity of the signals in each of the plurality of frequency bands.

8. Apparatus (100) according to claim 6 or 7.

9. To determine the similarity information, the apparatus (100) is configured to determine a magnitude-based weighted similarity by performing a magnitude-based weighting of similarities of at least two audio signals in each of a plurality of frequency bands; the apparatus (100) is configured to perform the adaptive equalization and / or the time dynamic equalization by using the magnitude-based weighted similarity. An apparatus (100) according to any one of claims 6 to 8.

10. the apparatus (100) is configured to perform the magnitude-based weighting by using a weighting function; 10. The apparatus (100) of claim 9.

11. the weighting function is a sigmoid function; 11. The apparatus (100) of claim 10.

12. the apparatus (100) is configured to perform the magnitude-based weighting by using magnitudes of the plurality of frequency bands to detect which of the plurality of frequency bands to use to calculate similarity information. An apparatus (100) according to any one of claims 9 to 11.

13. the apparatus (100) is configured to perform the magnitude-based weighting by using a certain number of frequency bands having the greatest magnitudes for calculating the similarity information. An apparatus (100) according to any one of claims 9 to 12.

14. the apparatus (100) is configured to determine the appropriate subset of one or more frequency bands from a plurality of frequency bands by using a magnitude of each of the plurality of frequency bands of the at least two audio signals to determine the appropriate subset; the apparatus (100) is configured to determine the similarity information by determining similarity information for each of the one or more frequency bands of the suitable subset without determining similarity information for each of the one or more frequency bands of the plurality of frequency bands that are not included in the suitable subset. An apparatus (100) according to any one of claims 6 to 13.

15. each frequency of the plurality of frequency bands is associated with a magnitude that is dependent on a magnitude of the frequency band of one or more of the at least two audio signals; the apparatus (100) is configured to determine the suitable subset of the one or more frequency bands such that the magnitude associated with each frequency band of the one or more frequency bands of the suitable subset is greater than or equal to the magnitude associated with each of the one or more frequency bands of the plurality of frequency bands not included in the suitable subset.

15. The apparatus (100) of claim 14.

16. the system for reproducing virtual sound (200) is configured to perform crosstalk cancellation by using a plurality of crosstalk cancellation coefficients; the apparatus (100) is configured to reduce the spectral distortion by performing adaptive equalization using a plurality of equalizer components and / or by performing time dynamic equalization; the apparatus (100) being configured to determine the plurality of equalizer components in response to one or more of the plurality of crosstalk cancellation coefficients. An apparatus (100) according to any one of claims 1 to 15.

17. the apparatus (100) is configured to determine the plurality of equalizer components by selecting a set of pre-calculated equalizer components from a set of two or more pre-calculated equalizer components in response to the crosstalk cancellation coefficients.

17. The apparatus (100) of claim 16.

18. The apparatus (100) is configured to determine the equalizer components at run-time in response to similarity information indicative of the information on the similarity of the at least two audio signals and / or in response to the crosstalk cancellation coefficients.

17. The apparatus (100) of claim 16.

19. the apparatus (100) is configured to determine the plurality of equalizer components by determining one or more combinations of the plurality of crosstalk cancellation coefficients, the combinations being a plurality of complex crosstalk cancellation coefficients in a frequency domain.

19. Apparatus (100) according to claim 16 or 18.

20. To determine the plurality of equalizer components, the apparatus (100) is configured to determine one or more linear combinations of the complex crosstalk cancellation coefficients in the frequency domain to determine the one or more combinations of the plurality of crosstalk cancellation coefficients.

20. The apparatus (100) of claim 19.

21. the apparatus (100) being configured to determine a single correction equalizer from the plurality of equalizer components; 21. The apparatus (100) of claim 20.

22. the apparatus (100) being configured to determine the single correction equalizer from the multiple equalizer components by weighting the multiple equalizer components before combining them to obtain the single correction equalizer.

22. The apparatus (100) of claim 21.

23. The method according to any one of claims 6 to 15, wherein the device (100) is configured to weight the equalizer components according to a similarity value, the similarity value depending on the similarity information.

21. The apparatus (100) of claim 20.

24. the device (100) is configured to perform adaptive equalization and / or by performing time dynamic equalization on one or more audio input signals of the system (200) to reproduce the virtual sound, 24. Apparatus (100) according to any one of claims 1 to 23.

25. The method according to claim 2, further comprising the steps of: (a) providing a virtual sound reproduction system for reproducing a virtual sound by performing an adaptive equalization and / or a time-dynamic equalization on two or more audio output signals of the system; An apparatus (100) according to any one of claims 3 to 24.

26. the device (100) is configured to perform adaptive equalization and / or by performing time dynamic equalization on crosstalk cancellation filter matrices used for crosstalk cancellation by the system (200) for reproducing the virtual sound, 26. Apparatus (100) according to any one of claims 1 to 25.

27. The method according to claim 2, further comprising the steps of: (a) providing a method for reducing the spectral distortion of a signal from a plurality of audio input signals; (b) providing a method for reducing the spectral distortion of a signal from a plurality of audio input signals; (c) providing a method for reducing the spectral distortion of a signal from a plurality of audio input signals; 27. Apparatus (100) according to any one of claims 3 to 26.

28. the apparatus (100) is configured to perform the adaptive equalization and / or to perform the time dynamic equalization by applying an average gain across two or more subbands.

28. Apparatus (100) according to any one of claims 1 to 27.

29. A system (200) for reproducing virtual sounds through speakers, said system (200) comprising: a speaker signal generator (150) for generating two or more audio output signals from one or more audio input signals; The system (200) comprises an apparatus (100) for reducing spectral distortion according to any one of claims 1 to 28, the apparatus (100) is configured to reduce the spectral distortion by performing adaptive equalization and / or time dynamic equalization on at least one of the one or more audio input signals and / or on at least one of the two or more audio output signals and / or on filter information used by the speaker signal generator on the one or more audio input signals or on one or more processed signals dependent on the one or more audio input signals, System (200).

30. said system (200) for reproducing virtual sound comprises a crosstalk cancellation system for performing crosstalk cancellation to remove and / or reduce and / or avoid crosstalk generated by said crosstalk cancellation system when reproducing said virtual sound through said loudspeakers, the apparatus (100) is configured to reduce spectral distortion resulting from performing the crosstalk cancellation.

30. The system (200) of claim 29.

31. the one or more audio input signals include two binaural audio signals; 31. The system (200) of claim 30.

32. The system (200) does not include the speaker.

32. The system (200) of any one of claims 29 to 31.

33. The system (200) comprises the speaker.

32. The system (200) of any one of claims 29 to 31.

34. A method for reducing spectral distortion in a system (200) for reproducing virtual sounds through speakers, comprising: The method includes reducing the spectral distortion by performing adaptive equalization and / or by performing time dynamic equalization. method.

35. 35. A computer program for performing the method according to claim 34 when the computer program is run on a computer or signal processor.

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