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For generating a low-frequency channel for a low-frequency loudspeaker arranged at a predetermined low-frequency loudspeaker position, a plurality of audio objects are initially provided, each audio object having an object position and an object description associated with it. Hereafter, a calculati

For generating a low-frequency channel for a low-frequency loudspeaker arranged at a predetermined low-frequency loudspeaker position, a plurality of audio objects are initially provided, each audio object having an object position and an object description associated with it. Hereafter, a calculation of an audio object scaling value is performed for each audio object on the basis of the object description, so that an actual amplitude state at least comes close to a target amplitude state at a reference playback position. Thereafter, each object signal is scaled with an associated audio object scaling value so as to then sum the scaled object signals. From the composite signal obtained there, a low-frequency channel is subsequently derived for the low-frequency loudspeaker, and is provided to the respective low-frequency loudspeaker. Due to the scaling of the individual object signals of the audio objects, this approach is independent of an actual situation of a multichannel playback system with regard to the number and density of the loudspeakers as well as with regard to the size of the presentation area actually present.

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1. An apparatus for generating a low-frequency channel for a low-frequency loudspeaker, comprising: a first provider for providing a plurality of audio objects, the plurality of audio objects comprising at least a first audio object and a second audio object, each audio object having an object signa

1. An apparatus for generating a low-frequency channel for a low-frequency loudspeaker, comprising: a first provider for providing a plurality of audio objects, the plurality of audio objects comprising at least a first audio object and a second audio object, each audio object having an object signal and an object description associated with the object signal;a calculator for calculating an audio object scaling value for each audio object in dependence on the object description associated with the object signal so that at least a first audio object scaling value for the first audio object and a second audio object scaling value for the second audio object is obtained;a scaler for scaling each object signal with an associated audio object scaling value so as to obtain at least a first scaled object signal for the first audio object and a second scaled object signal for the second audio object;a summer for summing at least the first scaled object signal and the second scaled object signal so as to obtain a composite signal; anda second provider for providing the low-frequency channel for the low-frequency loudspeaker on the basis of the composite signal. 2. The apparatus as claimed in claim 1, wherein the low-frequency loudspeaker is arranged at a predetermined loudspeaker position, the predetermined loudspeaker position differing from a reference playback position, and wherein the second provider for providing the low-frequency channel is configured to calculate a loudspeaker scaling value for the low-frequency loudspeaker in dependence on the predetermined loudspeaker position, so that a low-frequency signal at the reference playback position has a loudness which corresponds to a loudness of the composite signal within a predetermined tolerance range, andwherein the provider is further configured to scale the composite signal with the loudspeaker scaling value so as to generate the low-frequency channel. 3. The apparatus as claimed in claim 2, wherein several low-frequency loudspeakers are provided, and wherein the second provider is further configured to calculate the loudspeaker scaling values such that for each low-frequency loudspeaker, a loudspeaker scaling value in accordance with the following equation is obtained: (a1+a2+ . . . +an)·s=LSref,wherein LSref is a reference loudness at a reference playback position, wherein s is the composite signal, wherein al is the loudspeaker scaling value of a first low-frequency loudspeaker, wherein a2 is a loudspeaker scaling value of a second low-frequency loudspeaker, and wherein an is a loudspeaker scaling value of an nth low-frequency loudspeaker. 4. The apparatus as claimed in claim 3, wherein the loudspeaker scaling value of a low-frequency loudspeaker depends on a distance of the low-frequency loudspeaker from the reference playback position. 5. The apparatus as claimed in claim 1, wherein each object signal is a low-frequency signal having an upper cutoff frequency smaller than or equal to 250 Hz. 6. The apparatus as claimed in claim 1, wherein the composite signal has an upper cutoff frequency higher than 8 kHz, and wherein the second provider for providing the low-frequency channel is configured to conduct a low-pass filtering at a cutoff frequency smaller than or equal to 250 Hz. 7. The apparatus as claimed in claim 1, wherein an audio object of the plurality of audio objects includes an object description which includes an audio object position, andwherein the calculator for calculating an audio object scaling value for the audio object is configured to calculate the audio object scaling value in dependence on the audio object position of the audio object and on a reference playback position, and in dependence on an object loudness associated with the audio object. 8. The apparatus as claimed in claim 1, wherein a plurality of low-frequency channels for a plurality of low-frequency loudspeakers may be generated at predetermined low-frequency loudspeaker positions, andwherein the second provider is configured to calculate a loudspeaker scaling value for each low-frequency loudspeaker in dependence on the position of a low-frequency loudspeaker and in dependence on a number of further low-frequency loudspeakers,so that a low-frequency signal which is superposition of output signals of all low-frequency loudspeakers at the reference position has a loudness which corresponds to a loudness of the composite signal within a predetermined tolerance range. 9. The apparatus as claimed in claim 1, wherein the calculator for calculating audio object scaling values is further configured to calculate an audio object delay value for each audio object, the former depending on an object position and a reference playback position, andwherein the summer is configured to delay each object signal or each scaled object signal by the respective audio object delay value prior to summing. 10. The apparatus as claimed in claim 1, wherein the first provider is configured to calculate, for a low-frequency loudspeaker, a low-frequency loudspeaker delay value which depends on a distance of the low-frequency loudspeaker from the reference playback position, andwherein the second provider is further configured to take into account the low-frequency loudspeaker delay value when providing the low-frequency channel. 11. The apparatus as claimed in claim 1, which is configured to operate in a wave-field synthesis system with a wave-field synthesis module and an array of loudspeakers for exposing a presentation area to sound, the wave-field synthesis module being configured to receive an audio signal associated with a virtual sound source, as well as source position information associated with the virtual sound source, and to calculate component signals for the loudspeakers due to the virtual source while taking into account loudspeaker position information, and wherein the calculator for calculating the audio object scaling values includes a determiner for determining a correction value as an audio object scaling value, the determiner being configured to calculate the audio object scaling value such that it is based on a target amplitude state in the presentation area, the target amplitude state depending on a position of the virtual source or a type of the virtual source, and such that it is further based on an actual amplitude state in the presentation area which is based on the component signals for the loudspeakers due to the virtual source. 12. The apparatus as claimed in claim 11, wherein the determiner for determining the correction value is configured to calculate the target amplitude state for a predetermined point in the presentation area, and to determine the actual amplitude state for a zone in the presentation area which equals the predetermined point or extends around the predetermined point within a tolerance range. 13. The apparatus as claimed in claim 12, wherein the predetermined tolerance range is a sphere having a radius smaller than 2 meters around the predetermined point. 14. The apparatus as claimed in claim 11, wherein the virtual source is a source for plane waves, and wherein the determiner for determining the correction value is configured to determine a correction value wherein an amplitude state of the audio signal associated with the virtual source equals the target amplitude state. 15. The apparatus as claimed in claim 11, wherein the virtual source is a point source, and wherein the determiner for determining the correction factor is configured to operate on the basis of a target amplitude state which equals a quotient from an amplitude state of the audio signal associated with the virtual source, and the distance between the presentation area and the position of the virtual source. 16. The apparatus as claimed in claim 11, wherein the determiner for determining the correction value is configured to operate on the basis of an actual amplitude state, the determination of which takes into account a loudspeaker transmission function of the loudspeaker. 17. The apparatus as claimed in claim 11, wherein the determiner for determining the correction factor is configured to calculate, for each loudspeaker, a damping value which depends on the position of the loudspeaker and on a point to be contemplated in the presentation area, and wherein the determiner is further configured to weight the component signal of a loudspeaker with the damping value for the loudspeaker so as to obtain a weighted component signal and so as to further sum component signals or component signals, weighted accordingly, from other loudspeakers so as to obtain the actual amplitude state at the point contemplated on which the correction value is based. 18. The apparatus as claimed in claim 11, wherein the manipulator is configured to use that correction value as a correction factor which equals a quotient from the actual amplitude state and the target amplitude state. 19. The apparatus as claimed in claim 11, wherein the target amplitude state is a target sound level, and wherein the actual amplitude state is an actual sound level. 20. The apparatus as claimed in claim 19, wherein the target sound level and the actual sound level are based on a measure of an energy falling onto a reference area within a period of time. 21. The apparatus as claimed in claim 19, wherein the determiner for determining the correction value is configured to calculate the target amplitude state in that samples of the audio signal associated with the virtual source are squared sample by sample, and a number of squared samples, the number being a measure of an observation time, are summed to obtain the target amplitude state, and wherein the determiner for determining the correction value is further configured to calculate the actual amplitude state in that each component signal is squared sample by sample, and a number of squared samples, which equals the number of summed squared samples for calculating the target amplitude state, are added up so that an addition result for each component signal is obtained, and wherein the addition results from the component signals are further added up to obtain the actual amplitude state. 22. The apparatus as claimed in claim 11, wherein the determiner for determining the correction value comprises a look-up table which has position/correction-factor value pairs stored therein, a correction factor of a value pair depending on an arrangement of the loudspeakers in the array of loudspeakers, and on a position of a virtual source, and the correction factor being selected such that a deviation between an actual amplitude state due to the virtual source at the associated position and a target amplitude state is at least reduced when the correction factor is used by the manipulator. 23. The apparatus as claimed in claim 22, wherein the determiner is further configured to interpolate a current correction factor for a current position of the virtual source from one or several correction factors from position/correction-factor value pairs, whose position(s) is/are located adjacent to the current position. 24. A method for generating a low-frequency channel for a low-frequency loudspeaker, comprising: providing a plurality of audio objects, the plurality of audio objects comprising at least a first audio object and a second audio object, each audio object having an object signal and an object description associated with the object signal;calculating an audio object scaling value for each audio object in dependence on the object description associated with the object signal so that at least a first audio object scaling value for the first audio object and a second audio object scaling value for the second audio object is obtained;scaling each object signal with an associated audio object scaling value so as to obtain at least a first scaled object signal for the first audio object and a second scaled object signal for the second audio object;summing at least the first scaled object signal and the second scaled object signal so as to obtain a composite signal; andproviding the low-frequency channel for the low-frequency loudspeaker on the basis of the composite signal. 25. A computer program having a program code for performing the method for generating a low-frequency channel for a low-frequency loudspeaker, the method comprising: providing a plurality of audio objects, the plurality of audio objects comprising at least a first audio object and a second audio object, each audio object having an object signal and an object description associated with the object signal;calculating an audio object scaling value for each audio object in dependence on the object description associated with the object signal so that at least a first audio object scaling value for the first audio object and a second audio object scaling value for the second audio object is obtained;scaling each object signal with an associated audio object scaling value so as to obtain at least a first scaled object signal for the first audio object and a second scaled object signal for the second audio object;summing at least the first scaled object signal and the second scaled object signal so as to obtain a composite signal; andproviding the low-frequency channel for the low-frequency loudspeaker on the basis of the composite signal,when the program runs on a computer.