APPARATUS AND METHOD FOR DERIVING A DIRECTIONAL INFORMATION AND COMPUTER PROGRAM PRODUCT Description . Technical Field Embodiments of the present invention relate to an apparatus for deriving a directional information from a plurality of microphone signals or from a plurality of components of a microphone signal. Further embodiments relate to systems comprising such an apparatus. Further embodiments relate to a method for deriving a directional information from a plurality of microphone signals. 2. Background of the Invention Spatial sound recording aims at capturing a sound field with multiple microphones such that at the reproduction side, a listener perceives the sound image as it was present at the recording location. Standard approaches for spatial sound recording use conventional stereo microphones or more sophisticated combinations of directional microphones, e.g., such as the B-format microphones used in Ambisonics (M.A. Gerzon. Periphony, Widthheight sound reproduction, J . Audio Eng. Soc, 21(1):2-10, 1973). Commonly, most of these methods are referred to as coincident-microphone techniques. Alternatively, methods based on a parametric representation of sound fields can be applied, which are referred to as parametric spatial audio coders. These methods determine one or more downmix audio signals together with corresponding spatial side information, which are relevant for the perception of spatial sound. Examples are Directional Audio Coding (DirAC), as discussed in V. Pulkki, Spatial sound reproduction with directional audio coding, J . Audio Eng. Soc, 55(6):503—516, June 2007, or the so-called spatial audio microphones (SAM) approach proposed in C. Faller, Microphone front-ends for spatial audio coders. In 125th AES Convention, Paper 7508, San Francisco, Oct. 2008. The spatial cue information is determined in frequency subbands and basically consists of the direction-of-arrival (DOA) of sound and, sometimes, of the diffuseness of the sound field or other statistical measures. In a synthesis stage, the desired loudspeaker signals for reproduction are determined based on the downmix signals and the parametric side information. In addition to spatial audio recording, parametric approaches to sound field representations have been used in applications such as directional filtering (M. Kallinger, H. Ochsenfeld, G. Del Galdo, F. Kuech, D. Mahne, R. Schultz-Amling, and O. Thiergart, A spatial filtering approach for directional audio coding, in 126th AES Convention, Paper 7653, Munich, Germany, May 2009) or source localization (O. Thiergart, R. Schultz-Amling, G. Del Galdo, D. Mahne, and F. Kuech, Localization of sound sources in reverberant environments based on directional audio coding parameters, in 128th AES Convention, Paper 7853, New York City, NY, USA, Oct. 2009). These techniques are also based on directional parameters such as DOA of sound or the diffuseness of the sound field. One way to estimate directional information from the sound field, namely the direction of arrival of sound, is to measure the field in different points with an array of microphones. Several approaches have been proposed in the literature J . Chen, J. Benesty, and Y. Huang, Time delay estimation in room acoustic environments: An overview, in EURASIP Journal on Applied Signal Processing, Article ID 26503, 2006 using relative time delay estimates between the microphone signals. However, these approaches make use of the phase information of the microphone signals, leading inevitably to spatial aliasing. In fact, as higher frequencies are being analyzed, the wavelength becomes shorter. At a certain frequency, termed aliasing frequency, the wavelength is such that the identical phase readings correspond to two or more directions, so that an unambiguous estimation is not possible (at least without additional a priori information). There exists a large variety of methods to estimate the DOA of sound using arrays of microphones. An overview of common approaches is summarized in J. Chen, J . Benesty, and Y. Huang, Time delay estimation in room acoustic environments: An overview, in EURASIP Journal on Applied Signal Processing, Article ID 26503, 2006. These approaches have in common, that they exploit the phase relation of the microphone signals to estimate the DOA of sound. Often, the time difference between different sensors is determined first, and then the knowledge of the array geometry is exploited to compute the corresponding DOA. Other approaches evaluate the correlation between the different microphone signals in frequency subbands to estimate the DOA of sound (C. Faller, Microphone front-ends for spatial audio coders, in 125th AES Convention, Paper 7508, San Francisco, Oct. 2008 and J. Chen, J . Benesty, and Y. Huang, Time delay estimation in room acoustic environments: An overview, in EURASIP Journal on Applied Signal Processing, Article ID 26503, 2006). In DirAC the DOA estimate for each frequency band is determined based on the active sound intensity vector measured in the observed sound field. In the following the estimation of the directional parameters in DirAC is briefly summarized. Let P(k, n) denote the sound pressure and U(k, n) the particle velocity vector at frequency index k and time index n. Then, the active sound intensity vector is obtained as I a (k, n) = Re{ ( ,ri)U*(k, n)} ( 1) The superscript * denotes the conjugate complex and Re{ } is the real part of a complex number. p0 represents the mean density of air. Finally, the opposite direction of Ia(k, n) points to the DOA of sound: I a ( ) DOA , n ) = Additionally, the diffuseness of the sound field can be determined, e.g., according to (3) In practice, the particle velocity vector is computed from the pressure gradient of closely spaced omnidirectional microphone capsules, often referred to as differential microphone array. Considering Fig. 2, the x component of the particle velocity vector can, e.g., be computed using a pair of microphones according to Ux (k, n ) = K{k) [Pi (fe, n) - i ¾( , n)] , (4) where K(k) represents a frequency dependent normalization factor. Its value depends on the microphone configuration, e.g. the distance of the microphones and/or their directivity patterns. The remaining components Uy(k, n) (and U (k, n)) of U(kn) can be determined analogously by combining suitable pairs of microphones. As shown in M. Kallinger, F. Kuech, R. Schultz-Amling, G. Del Galdo, J . Ahonen, and V. Pulkki, Analysis and Adjustment of Planar Microphone Arrays for Application in Directional Audio Coding, in 124th AES Convention, Paper 7374, Amsterdam, the Netherlands, May 2008, spatial aliasing affects the phase information of the particle velocity vector, prohibiting the use of pressure gradients for the active sound intensity estimation at high frequencies. This spatial aliasing yields ambiguities in the DOA estimates. As can be shown, the maximum frequency fmax, where unambiguous DOA estimates can be obtained based on active sound intensity, is determined by the distance of the microphone pairs. Additionally, the estimation of directional parameters such as diffuseness of a sound field are also affected. In case of omnidirectional microphones with a distance d, this maximum frequency is given by (5) where c denotes the speed of sound propagation. Typically, the required frequency range of applications exploiting the directional information of sound fields is larger than the spatial aliasing limit fmax to be expected for practical microphone configuration. Notice that reducing the microphone spacing d, which increases the spatial aliasing limit fmax, is not a feasible solution for most applications, as a too small d significantly reduces the estimation reliability at low frequencies in practice. Thus, new methods are needed to overcome the limitations of current directional parameter estimation techniques at high frequencies. 3. Summary of the Invention It is an objective of embodiments of the present invention to create a concept, which allows for a better determination of a directional information above a spatial aliasing limit frequency. This objective is solved by an apparatus according to claim 1, systems according to claims 15 and 16, a method according to claim 18 and a computer program according to claim 19. Embodiments provide an apparatus for deriving a directional information from a plurality of microphone signals or from a plurality of components of a microphone signal, wherein different effective microphone look directions are associated with the microphone signals or components. The apparatus comprises a combiner configured to obtain a magnitude from a microphone signal or a component of the microphone signal. Furthermore, the combiner is configured to combine (e.g. linearly combine) direction information items describing the effective microphone look direction, such that a direction information item describing a given effective microphone look direction is weighted in dependence on the magnitude value of the microphone signal, or of the component of the microphone signal, associated with the given effective microphone look direction, to derive the directional information. It has been found that the problem of spatial aliasing in directional parameter estimation results from ambiguities in the phase information within the microphone signals. It is an idea of embodiments of the present invention to overcome this problem by deriving a directional information based on magnitude values of the microphone signals. It has been found that by deriving the directional information based on magnitude values of the microphone signals or of components of the microphone signals, ambiguities, as they may occur in traditional systems using the phase information to determine the directional information do not occur. Hence, embodiments enable a determination of a directional information even above a spatial aliasing limit, above which a determination of the directional information is not (or only with errors) possible using phase information. In other words, the use of the magnitude values of the microphone signals or of the components of the microphone signals is especially beneficial within frequency regions where spatial aliasing or other phase distortions are expected, since these phase distortions do not have an influence on the magnitude values and, therefore, do not lead to ambiguities in the directional information determination. According to some embodiments, an effective microphone look direction associated to a microphone signal describes the direction where the microphone from which the microphone signal is derived has its maximum response (or its highest sensitivity). As an example, the microphone may be a directional microphone possessing a non isotropic pick up pattern and the effective microphone look direction can be defined as the direction where the pick up pattern of the microphone has its maximum. Hence, for a directional microphone the effective microphone look direction may be equal to the microphone look direction (describing the direction towards which the directional microphone has a maximum sensitivity), e.g. when no objects modifying the pick-up pattern of the directional microphone are placed near the microphone. The effective microphone look direction may be different to the microphone look direction of the directional microphone if the directional microphone is placed near an object that has the effect of modifying its pick-up pattern. In this case the effective microphone look direction may describe the direction, where the directional microphone has its maximum response. In the case of an omnidirectional microphone, an effective response pattern of the omnidirectional microphone may be shaped, for example, using a shadowing object (which has an effect of the effect of modifying the pick-up pattern of the microphone), such that the shaped effective response pattern has an effective microphone look direction which is the direction of maximum response of the omnidirectional microphone with the shaped effective response pattern. According to further embodiments, the directional information may be a directional information of a sound field pointing towards the direction from which the sound field is propagating (for example, at certain frequency and time indices). The plurality of microphone signals may describe the sound field. According to some embodiments, a direction information item describing a given effective microphone look direction maybe a vector pointing into the given effective microphone look direction. According to further embodiments, the direction information items may be unit vectors, such that direction information items associated with different effective microphone look directions have equal norms (but different directions). Therefore, a norm of a weighted vector linearly combined by the combiner is determined by the magnitude value of the microphone signal or the component of the microphone signal associated to the direction information item of the weighted vector. According to further embodiments, the combiner may be configured to obtain a magnitude value, such that the magnitude value describes a magnitude of a spectral coefficient (as a component of the microphone signal) representing a spectral sub-region of the microphone signal of the component of the microphone signal. In other words, embodiments may extract the actual information of a sound field (for example analyzed in a time frequency domain) from the magnitudes of the spectra of the microphones used for deriving the microphone signals. According to further embodiments, only the magnitude values (or the magnitude information) of the microphone signals (or of the microphone spectra) are used in the estimation process for deriving the directional information, as the phase term is corrupted by the spatial aliasing effect. In other words, embodiments create an apparatus and a method for directional parameter estimation using only the magnitude information of microphone signals or components of the microphone signals and the spectrum, respectively. According to further embodiments, the output of the magnitude based directional parameter estimation (the directional information) can be combined with other techniques which also consider phase information. According to further embodiments, the magnitude value may describe a magnitude of the microphone signal or of the component. 4. Short Description of the Figures Embodiments of the present invention will be described in detail using the accompanying figures, in which: Fig. 1 shows a block schematic diagram of an apparatus according to an embodiment of the present invention; Fig. 2 shows an illustration of a microphone configuration using four omnidirectional capsules; providing sound pressure signals P (k, n) with i = 1, . . . , 4; Fig. 3 shows an illustration of a microphone configuration using four directional microphones with cardioid pick up patterns; Fig. 4 shows an illustration of a microphone configuration employing a rigid cylinder to cause scattering and shadowing effects; Fig. 5 shows an illustration of a microphone configuration similar to Fig. 4, but employing a different microphone placement; Fig. 6 shows an illustration of a microphone configuration employing a rigid hemisphere to cause scattering and shadowing effects; Fig. 7 shows an illustration of a 3D microphone configuration employing a rigid sphere to cause shadowing effects; Fig. 8 shows a flow diagram of a method according to an embodiment; Fig. 9 shows a block schematic diagram of a system according to an embodiment; Fig. 10 shows a block schematic diagram of a system according to a further embodiment of the present invention; Fig. 11 shows an illustration of an array of four omnidirectional microphones with spacing of d between the opposing microphones; Fig. 12 shows an illustration of an array of four omnidirectional microphones, which are mounted on the end of a cylinder; Fig. 13 shows a diagram of a directivity index DI in decibels as a function of ka, which represents a diaphragm circumference of an omnidirectional microphone divided by the wavelength; Fig. 1 shows logarithmic directional patterns with G.R.A.S. microphone; Fig. 15 shows logarithmic directional patterns with AKG microphone; and Fig. 16 shows diagram results for direction analysis expressed as root-mean-square error (RMSE). Before embodiments of the present invention will be described in more detail using the accompanying figures, it is to be pointed out that the same or functionally equal elements are provided with the same reference numbers and that a repeated description of elements provided with the same reference numbers is omitted. Hence, descriptions provided for elements with the same reference numbers are mutually exchangeable. 5. Detailed Description of Embodiments of the Present Invention 5.1 Apparatus According to Fig. 1 Fig. 1 shows an apparatus 00 according to an embodiment of the present invention. The apparatus 100 for deriving a directional information 101 (also denoted as d(k, n)) from a plurality of microphone signals 103^0 103N (also denoted as to PN) or from a plurality of components of a microphone signal comprises a combiner 105. The combiner 105 is configured to obtain a magnitude value from a microphone signal or a component of the microphone signal, and to linearly combine direction information items describing effective microphone look directions being associated with the microphone signals 103i to 103N or the components, such that a direction information item describing a given effective microphone look direction is weighted in dependence on the magnitude value of the microphone signal, or of the component of the microphone signal, associated with the given effective microphone look direction to derive the directional information 101. A component of an i-th microphone signal Pj may be denoted as P (k, n). The component Pj(k, n) of the microphone signal i may be a value of the microphone signal R,· at frequency index k and time index n. The microphone signal Pj may be derived from an i-th microphone and may be available to the combiner 05 in the time frequency representation comprising a plurality of components Pj(k, n) for different frequency indices k and time indices n. As an example, the microphone signals Pi to P may be Sound Pressure Signals, as they can be derived from B-Format microphones. Therefore, each component Pj(k, n) may correspond to a time frequency tile (k, n). The combiner 105 may be configured to obtain the magnitude value such that the magnitude value describes a magnitude of a spectral coefficient representing a spectral sub-region of the microphone signal Pj. This spectral coefficient may be a component P;(k, n) of the microphone signal Pj. The spectral sub-region may be defined by the frequency index k of the component Pj(k, n). Furthermore, the combiner 105 may be configured to derive the directional information 101 on the basis of a time frequency representation of the microphone signals, for example, in which a microphone signal Pj is represented by a plurality of components Pi(k, n), each component being associated to a time frequency tile (k, n). As described in the introductory part of this application, by obtaining the directional information (k, n) based on the magnitude values of the microphone signals Pi to or of components of a microphone signal a determination of the directional information d(k, n) even with higher frequency for the microphone signals to P , e.g. for components Pj(k, n) to P (k, n) having a frequency index above a frequency index of the spectral aliasing frequency fma , can be achieved, since spatial aliasing or other phase distortions cannot occur. In the following a detailed example of an embodiment of the present invention is given, which is based on a combination of the magnitudes of the microphone signals (directional magnitude combination), and how it can be performed by the apparatus 100 according to Fig. 1. The directional information d(k, n), also denoted as DOA estimate, is obtained by interpreting the magnitude of each microphone signal (or of each component of a microphone signal) as a corresponding vector in a two-dimensional (2D) or threedimensional (3D) space. Let dt(k, n) be the true or desired vector which points towards the direction from which the sound field is propagating at frequency and time indices k and n respectively. In other words, the DOA of sound corresponds to the direction of dt(k, n). Estimating dt(k, n) so that the directional information from the sound field can be extracted is the goal of embodiments of the invention. Let further bl 5 b2, . . . , be vectors (e.g. unit norm vectors) pointing into the look direction of the N directional microphones. The look direction of a directional microphone is defined as the direction, where the pick-up pattern has its maximum. Analogously, in case of scattering/shadowing objects are included in the microphone configuration, the vectors bi, b2, . . . , point in the direction of maximum response of the corresponding microphone. The vectors bi, b2, . . . , may be designated as direction information items describing effective microphone look directions of the first to the N-th microphone. In this example, the direction information items are vectors pointing into corresponding effective microphone look directions. According to further embodiments, a direction information item may also be a scalar, for example an angle describing a look direction of a corresponding microphone. Furthermore, in this example the direction information items may be unit norm vectors, such that vectors associated with different effective microphone look directions have equal norms. It should also be noted, that the proposed method may work best if the sum of the vectors bj, corresponding to the effective microphone look directions of the microphones, equals zero (e.g. within a tolerance range), i.e., = o. i-1 (6) In some embodiments the tolerance range may be ±30%, ±20%, ±10%, ±5%» of one of the direction information items used to derive the sum (e.g. of the direction information item having the largest norm of the direction information item having the smallest norm, or of the direction information item having the norm closest to the average of all norms of the direction items used to derive the sum). In some embodiments effective microphone look directions may not be equally distributed with regard to a coordinate system. For example, assuming a system in which a first effective microphone look direction of a first microphone is EAST (e.g. 0 degrees in a 2- dimensional coordinate system), a second effective microphone look direction of a second microphone is NORTH-EAST (e.g. 45 degrees in the 2-dimensional coordinate system), a third microphone look direction of a third microphone is NORTH (e.g. 90 degrees in the 2-dimensional coordinate system), and a fourth effective microphone look direction of a fourth microphone is SOUTH-WEST (e.g. -135 degrees in the 2-dimensional coordinate system), having the direction information items being unit norm vectors would result in: b = [ 1 0]T for the first effective microphone look direction; b = [1/ 1 2 ] for the second effective microphone look direction; b3= [0 l ] for the third effective microphone look direction; and b4= [— 1 2 - 1/ 2 ] for the fourth effective microphone look direction. This would lead to a non-zero sum of the vectors of: As in some embodiments, it is desired to have a sum of the vectors being zero, a direction information item being a vector pointing into an effective microphone look direction may be scaled. In this example, the direction information item b4 may be scaled, such as: b4= [-(l + l /V2) -(1 + 1 ) ] resulting in a sum bSUmof the vectors being equal to zero: bsum= bi+b2+b 3+b4= [0 0] . In other words, according to some embodiments, different direction information items being vectors pointing into different effective microphone look directions may have different norms, which may be chosen such that a sum of the direction information items equals zero. The estimate d of the true vector dt(k, n), and therefore the directional information to be determined can be defined as N (7) where P ,(k, n) denotes the signal of the i-th microphone (or of the component of the microphone signal R,· of the i-th microphone) associated to the frequency tile (k, n). The equation (7) forms a linear combination of the direction information items b to of a first microphone to a N-th microphone weighted by magnitude values of components Pi(k, n) to PN , n) of microphone signals P to P derived from the first to the N-th microphone. Therefore, the combiner 105 may calculate the equation (7) to derive the directional information 101 (d(k, n)). As can be seen from eq. (7) the combiner 105 may be configured to linearly combine the direction information items to weighted in dependence on the magnitude values being associated to a given time frequency tile (k, n) in order to derive the directional information d(k, n) for the given time frequency tile (k, n). According to further embodiments, the combiner 105 may be configured to linearly combine the direction information items b to weighted only in dependence on the magnitude values being associated to the given time frequency tile (k, n). Furthermore, from equation (7) it can be seen that the combiner 105 may be configured to linearly combine for a plurality of different time frequency tiles the same directional information items b to (as these are independent from the time frequency tiles) describing different effective microphone look directions, but the direction information items may be weighted differently in dependence on the magnitude values associated to the different time frequency tiles. As the direction information items b to b may be unit vectors a norm of a weighted vector being formed by a multiplication of a direction information item b and a magnitude value may be defined by the magnitude value. Weighted vectors for the same effective microphone look direction but different time frequency tiles may have the same direction but differ in their norms due to the different magnitude values for different time frequency tiles. According to some embodiments, the weighted values may be scalar values. The factor k shown in eq. (7) may be chosen freely. In the case that k = 2 and that opposing microphones (from which the microphone signals Pi to P are derived from) are equidistant, the directional information d(k, n) is proportional to the energy gradient in the center of the array (for example in a set of two microphones). In other words the combiner 105 may be configured to obtain squared magnitude values based on the magnitude values, a squared magnitude value describing a power of a component P (k, n) of a microphone signal P . Furthermore, the combiner 105 may be configured to linearly combine the direction information items to such that a direction information item b is weighted in dependence on the squared magnitude value of the component P (k, n) of the microphone signal associated with the corresponding look direction (of the i-th microphone). From d (k, n) the directional information expressed with azimuth f and elevation 3 angles is easily obtained considering that (8) In some applications, when only 2D analysis is required, four directional microphones, e.g., arranged as in Fig. 3, can be employed. In this case, the direction information items may be chosen as: b = [1 o o]T T (10) 4 = fo - 1 o T ( 12) so that (7) becomes dx = R , h) - \P2 (k n)\ K (13) dy = \P (k, n)\ - \P (k, n)\ (14) This approach can analogously be applied in case of rigid objects placed in the microphone configuration. As an example, Fig. 4 and 5, illustrate the case of a cylindrical object placed in the middle of an array of four microphones. Another example is shown in Fig. 6, where the scattering object has the shape of a hemisphere. An example of a 3D configuration is shown in Fig. 7, where six microphones are distributed over a rigid sphere. In this case, the z component of the vector d(k, n) can be obtained analogously to (9) - (14): 5 = [0 0 1] T (15) yielding dz = \P5 (k, n ) \ - \P k , n)\ . (17) A well known 3D configuration of directional microphones which is suitable for application in embodiments of this invention is the so-called A-format microphone, as described in P.G. Craven and M.A. Gerzon, US4042779 (A), 1977. To follow the proposed directional magnitude combination approach, certain assumptions need to be fulfilled. If directional microphones are employed, then for each microphone the pick up patterns should be approximately symmetric with respect to the orientation or look direction of the microphones. If the scattering/shadowing approach is used, then scattering/shadowing effects should be approximately symmetric with respect to the direction of maximum response. These assumptions are easily met when the array is constructed as in the examples shown in Figs. 3 to 7. Application in DirAC The above discussion considers the estimation of the directional information (the DOA) only. In the context of directional coding information about the diffuseness of a sound field may additionally be required. A straightforward approach is obtained by simply equating the estimated vector d(k, n) or determined directional information with the opposite direction of the active sound intensity vector Ia(k, n): I &(k, n ) = -d(k, n). (18) This is possible as d(k, n) contains information related to the energetic gradient. Then, the diffuseness can be computed according to (3). 5.2. Method According to Figure 8 Further embodiments of the present invention create a method for deriving a directional information from a plurality of microphone signals or from a plurality of components of a microphone signal, wherein different effective microphone look directions are associated with the microphone signals. Such a method 800 is shown in a flow diagram in Fig. 8. The method 800 comprises a step 801 of obtaining a magnitude from a microphone signal or a component of the microphone signal. Furthermore, the method 800 comprises a step 803 of combining (e.g. linearly combining) direction information items describing the effective microphone look directions, such that a direction information item describing a given effective microphone look direction is weighted in dependence on the magnitude value of the microphone signal or of the component of the microphone signal associated with the corresponding effective microphone look direction, to derive the directional information. The method 800 may be performed by the apparatus 100 (for example by the combiner 105 of the apparatus 100). In the following, two systems according to embodiments may be described for acquiring the microphone signals and deriving a directional information from these microphone signals using Figs. 9 and 10. 5.3 Systems According to Fig. 9 and Fig. 10 As commonly known, the use of the pressure magnitude to extract directional information is not practical when using omnidirectional microphones. In fact, the magnitude differences due to the different distances traveled by the sound to reach the microphones is normally too small to be measured, so that most known algorithms mainly rely on the phase information. Embodiments overcome the problem of spatial aliasing in directional parameter estimation. The systems described in the following make use of microphone arrays adequately designed so that there exists a measurable magnitude difference in the microphone signals which is dependent on the direction of arrival. (Only) This magnitude information of the microphone spectra is then used in the estimation process, as the phase term is corrupted by the spatial aliasing effect. Embodiments comprise extracting directional information (such as DOA or diffuseness) of a sound field analyzed in a time-frequency domain from only the magnitudes of the spectra of two or more microphones, or of one microphone subsequently placed in two or more positions, e.g., by making one microphone rotate about an axis. This is possible when the magnitudes vary sufficiently strong in a predictable way depending on the direction of arrival. This can be achieved in two ways, namely by 1. employing directional microphones (i.e., possessing a non isotropic pick up pattern such as cardioid microphones), where each microphone points to a different direction, or by 2. realizing for each microphone or microphone position a unique scattering and/or shadowing effect. This can be achieved for instance by employing a physical object in the center of the microphone configuration. Suitable objects modify the magnitudes of the microphone signals in a known way by means of scattering and/or shadowing effects. An example for a system using the first method is shown in Fig. 9. 5.3.1 System Using Directional Microphones According to Fig. 9 Fig. 9 shows a block schematic diagram of a system 900, the system comprises an apparatus, for example the apparatus 100 according to Fig. 1. Furthermore, the system 900 comprises a first directional microphone 901 having a first effective microphone look direction 903] for deriving a first microphone signal 103] of the plurality of microphone signals of the apparatus 100. The first microphone signal 103 is associated with the first look direction 903 ! . Furthermore, the system 900 comprises a second directional microphone 90 2 having a second effective microphone look direction 9032 for deriving a second microphone signal 1032 of the plurality of microphone signals of the apparatus 100. The second microphone signal 1032 is associated with the second look direction 9032. Furthermore, the first look direction 903 1 is different from the second look direction 9032. For example, the look directions 903 , 9032 may be opposing. A further extension to this concept is shown in Fig. 3, where four cardioid microphones (directional microphones) are pointed towards opposing directions of a Cartesian coordinate system. The microphone positions are marked by black circuits. By applying directional microphones it can be achieved that magnitude differences between the directional microphones 901 1, 90 12 are large enough to determine the directional information 101. An example of a system using the second method to achieve a strong variation of magnitudes of different microphone signals for omnidirectional microphones is shown in Fig. 10. 5.3.2 System Using Omnidirectional Microphones According to Fig. 10 Fig. 10 shows a system 1000 comprising an apparatus, for example, the apparatus 100 according to Fig. 1, for deriving a directional information 101 from a plurality of microphone signals or components of a microphone signal. Furthermore, the system 1000 comprises a first omnidirectional microphone l OO for deriving a first microphone signal 103] of the plurality of microphone signals of the apparatus 100. Furthermore, the system 1000 comprises a second omnidirectional microphone 1001 2 for deriving a second microphone signal 1032 of the plurality of microphone signals of the apparatus 100. Furthermore, the system 1000 comprises a shadowing object 1005 (also denoted as scattering object 1005) placed between the first omnidirectional microphone 1001 1 and the second omnidirectional microphone 1001 2 for shaping effective response patterns of the first omnidirectional microphone 1001 and of the second omnidirectional microphone 1001 2, such that a shaped effective response pattern of the first omnidirectional microphone lOO comprises a first effective microphone look direction 1003j and a shaped effected pattern of the second omnidirectional microphone 1001 2 comprises a second effective microphone look direction 10032. In other words, by using the shadowing object 1005 between the omnidirectional microphones 1001 , 1001 a directional behavior of the omnidirectional microphones 1001 , 1001 2 can be achieved such that measurable magnitude differences between the omnidirectional microphones 1001 1, 10012 even with a small distance between the two omnidirectional microphones OO , 1001 2 can be achieved. Further optional extensions to the system 1000 are given in Fig. 4 to Fig. 6, in which different geometric objects are placed in the middle of a conventional array of four (omnidirectional) microphones. Fig. 4 shows an illustration of a microphone configuration employing an object 1005 to cause scattering and shadowing effects. In this example in Fig. 4 the object is a rigid cylinder. The microphone positions of four (omnidirectional) microphones lOO to 10014 are marked by the black circuits. Fig. 5 shows an illustration of a microphone configuration similar to Fig. 4, but employing a different microphone placement (on a rigid surface of a rigid cylinder). The microphone positions of the four (omnidirectional) microphones lOO to 1001 4 are marked by the black circuits. In the example shown in Fig. 5 the shadowing object 1005 comprises the rigid cylinder and the rigid surface. Fig. 6 shows an illustration of a microphone configuration employing a further object 1005 to cause scattering and shadowing effects. In this example, the object 1005 is a rigid hemisphere (with a rigid surface). The microphone positions of the four (omnidirectional) microphones l OO to 1001 are marked by the black circuits. Furthermore, Fig. 7 shows an example for a three-dimensional DOA estimation (a threedimensional directional information derivation) using six (omnidirectional) microphones 1001]. to 1001 distributed over a rigid sphere. In other words, Fig. 6 shows an illustration of a 3D microphone configuration employing an object 1005 to cause shadowing effects. In this example, the object is a rigid sphere. The microphone positions of the (omnidirectional) microphones 1001 to 1001 6 are marked by the black circuits. From the magnitude differences between the different microphone signals generated by the different microphones shown in Figs. 2 to 7 and 9 to 10, embodiments compute the directional information following the approach explained in conjunction with the apparatus 100 according to Fig. 1. According to further embodiments, the first directional microphone 901 or the first omnidirectional microphone 1001 1 and the second directional microphone 9012 or the second omnidirectional microphone 1001 2 may be arranged such that a sum of a first direction information item being a vector pointing in the first effective microphone look direction 903 1, 1003] and of a second direction information item being a vector pointing into the second effective microphone look direction 9032, 10032 equals 0 within a tolerance range of +/- 5 %, +/- 10 %, +/- 20 % or +/- 30 % of the first direction information item or the second direction information item. In other words, equation (6) may apply to the microphones of the systems 900, 1000, in which b is a direction information item of the i-th microphone being a unit vector pointing in the effective microphone look direction of the i-th microphone. In the following, alternative solutions for using the magnitude information of the microphone signals for directional parameter estimation will be described. 5.4 Alternate Solutions 5.4.1 Correlation Based Approach An alternative approach to exploit solely the magnitude information of microphone signals for directional parameter estimation is proposed in this section. It is based on correlations between magnitude spectra of the microphone signals and corresponding a priori determined magnitude spectra obtained from models or measurements. Let Sj(k, n) = |P;(k, n)|K denote the magnitude or power spectrum of the i-th microphone signal. Then, we define the measured magnitude array response S(k, n) of the N microphones as S k , n ) = [S k , n), S 2 k , n), S N (k, n)} T . (19) The corresponding magnitude array manifold of the microphone array is denoted by SM( P, k, n). The magnitude array manifold obviously depends on the DOA of sound f if directional microphones with different look direction or scattering/shadowing with objects within the array are used. The influence on the DOA of sound on the array manifold depends on the actual array configuration, and it is influenced by the directional patterns of the microphones and/or scattering object included in the microphone configuration. The array manifold can be determined from measurements of the array, where sound is played back from different directions. Alternatively, physical models can be applied. The effect of a cylindrical scatterer on the sound pressure distribution on its surface is, e.g., described in H. Teutsch and W. Kellermann, Acoustic source detection and localization based on wavefield decomposition using circular microphone arrays, J . Acoust. Soc. Am., 5(120), 2006. To determine the desired estimate of the DOA of sound, the magnitude array response and the magnitude array manifold are correlated. The estimated DOA corresponds to the maximum of the normalized correlation according to (20) Although we have presented only the 2D case for the DOA estimation here, it is obvious that the 3D DOA estimation including azimuth and elevation can be performed analogously. 5.4.2 Noise Subspace Based Approach An alternative approach to exploit solely the magnitude information of microphone signals for directional parameter estimation is proposed in this section. It is based on the well known root MUSIC algorithm (R. Schmidt, Multiple emitter location and signal parameter estimation, IEEE Transactions on Antennas and Propagation, 34(3):276-280, 1986), with the exception that in the example shown only the magnitude information is processed. Let S(k, n) be the measured magnitude array response, as defined in (19). In the following the dependencies on k and n are omitted, as all steps are carried out separately for each time frequency bin. The correlation matrix R can be computed with R = E{ , where (·)H denotes the conjugate transpose and E{·} is the expectation operator. The expectation is usually approximated by a temporal and/or spectral averaging process in the practical application. The eigenvalue decomposition of R can be written as (22) where , are the eigenvalues and N is the number of microphones or measurement positions. Now, when a strong plane wave arrives at the microphone array, one relatively large eigenvalue l is obtained, while all other eigenvalues are close to zero. The eigenvectors, which correspond to the latter eigenvalues, form the so-called noise subspace Qn. This matrix is orthogonal to the so-called signal subspace Qs, which contains the eigenvector(s) corresponding to the largest eigenvalue(s). The so-called MUSIC spectrum can be computed with (23) where the steering vector s( 0. 12. Apparatus according to one of the preceding claims, wherein the combiner is configured to derive the directional information (d(k, n)) on the basis of the magnitude values and independent from phases of the microphone signals (P to PN) or of the components (Pj(k, n)) of the microphone signal (P ) in a first frequency range; and wherein the combiner is further configured to derive the directional information in dependence on the phases of the microphone signals (Pi to PN) or of the components (Pi(k, n)) of the microphone signal (P ) in a second frequency range. 13. Apparatus according to one of the preceding claims, wherein the combiner is configured such that the direction information item (b ) is weighted solely in dependence on the magnitude value. 14. Apparatus (100) according to one of the preceding claims, wherein the combiner (105) is configured to linearly combine the direction information items (b to N) . 15. System (900) comprising: an apparatus (100) according to one of the preceding claims, a first directional microphone (901 having a first effective microphone look direction (9030 for deriving a first microphone signal (1030 ° f e plurality of microphone signals, the first microphone signal (1030 being associated with a first effective microphone look direction (9030; d a second directional microphone (9012) having a second effective microphone look direction (9032) for deriving a second microphone signal (1032) of the plurality of microphone signals, the second microphone signal (1032) being associated with the second effective microphone look direction (903 ); and wherein the first look direction (9030 is different from the second look direction (9032) . 16. System (1000) comprising: an apparatus according to one of claims 1 to 14, a first omnidirectional microphone (10010 f deriving a first microphone signal (103i,) of the plurality of microphone signals; a second omnidirectional microphone (1001 2) for deriving a second microphone signal (1032) ; and a shadowing object (1005) placed between the first omnidirectional microphone (1001 ) and the second omnidirectional microphone (1001 2) for shaping effective response patterns of the first omnidirectional microphone (1001 and of the second omnidirectional microphone (1001 ), such that a shaped effective response pattern of the first omnidirectional microphone (10010 comprises a first effective microphone look direction (10030 and a shaped effective response pattern of the second omnidirectional microphone (1001 2) comprises a second effective microphone look direction (10032), being different from the first effective microphone look direction (10030. System according to one of claims 15 or 16, wherein the directional microphones (901 1, 9012) or the omnidirectional microphones (lOOl 1001 2) are arranged such that a sum of direction information items being vectors pointing in the effective microphone look directions (903 \ , 9032, 1003 l 10032) equals zero within a tolerance range of ± 30 % of the norm of one of the direction information items. Method (800) for deriving a directional information from a plurality of microphone signals or from a plurality of components of a microphone signal, wherein different effective microphone look directions are associated with the microphone signals or the components, the method comprising: obtaining (801) a magnitude value from the microphone signal or a component of the microphone signal; and combining (803) direction information items describing the effective microphone look directions, such that a direction information item describing a given effective microphone look direction is weighted in dependence on the magnitude value of the microphone signal or of the component of the microphone signal associated with the given effective microphone look direction, to derive the directional information. 19. Computer program having a program code for, when running on a computer, performing the method according to claim 18.