Spatial rendering of reverberation

Abstract

A method for generating a reverberated audio signal, the apparatus comprising: obtaining at least one audio signal; obtaining at least one space room impulse response; determining at least one parameter based on the at least one spatial room impulse response, the at least one parameter for the at least one spatial direction; configuring the at least one reverberator based on the determined at least one parameter such that the at least one reverberator is configured to output audio in at least one spatial direction; and generating at least one reverberated audio signal based on the configured at least one reverberator and at least one audio signal.

Description

Technical Field

[0001] The present application relates to apparatus and methods for generating and using spatial rendering of reverberation, but not exclusively to apparatus and methods for spatial rendering of reverberation in augmented reality and / or virtual reality devices. Background Art

[0002] Reverberation is the persistence of sound in a space after the actual sound source has ceased. Different spaces are characterized by different reverberation properties. In order to convey the spatial impression of an environment, it is important to reproduce the reverberation perceptually accurately. Room acoustics are usually modeled with a separately synthesized early reflection component and a statistical model for the diffuse late reverberation. Figure 1 Depicted is an example of a synthesized room impulse response showing amplitude 101 over time 103, where direct sound 105 is followed by discrete early reflections 107 with directions of arrival (DOA) and diffuse late reverberation 109 which may also have a direction of arrival or be synthesized without any specific direction of arrival.

[0003] One approach to reproducing reverberation is to use a set of N loudspeakers (or virtual loudspeakers using a set of head-related transfer functions (HRTF) binaural reproduction). These loudspeakers are positioned somewhat uniformly around the listener. Mutually incoherent reverberant signals are reproduced from these loudspeakers, resulting in the perception of ambient diffuse reverberation.

[0004] The location and number of loudspeakers suitable for producing a diffuse perception have been studied. Examples are K. Hiyama, S. Komiyama and K. Hamasaki, "The Minimum Number of Loudspeakers and Its Arrangement for Reproducing the Spatial Impression of Diffuse Sound Field, AES, 113th Meeting, 2002" and C. Kirch, J. Poppitz, T. Wendt, S. van der Par and S. Ewert, "Spatial Resolution of Late Reverberation in Virtual Acoustic Environments, submitted to Trends in Hearing (currently available at https: / / journals.sagepub.com / doi / full / 10.1177 / 23312165211054924, 2021". It has been found that, depending on the location of the loudspeakers, approximately 6-12 loudspeakers are needed.

[0005] The reverberations produced by different loudspeakers must be mutually incoherent. In a simple case, reverberations can be produced using different channels of the same reverberator, where the output channels are uncorrelated but otherwise share the same acoustic properties, such as RT60 time and level (specifically, diffuse-to-direct or diffuse-to-source ratios, or reverberant-to-direct ratios). Such uncorrelated outputs sharing the same acoustic properties can be obtained, for example, by tapping the output of a feedback delay network (FDN) reverberator (with appropriately tuned delay line lengths), or from a reverberator based on the use of decaying uncorrelated noise (by using different uncorrelated noise sequences for different channels). In this case, the different reverberation signals have virtually the same characteristics, and the reverberation is generally perceived to be similar for all directions.

[0006] In some other cases, the reverberation for different speakers may be adjusted based on the acoustic environment. For example, in some cases, it is desirable to adjust the spatial characteristics of the reverberation depending on the direction from which part of the diffuse late reverberation originates. An example is to use a shorter RT60 time for reverberation signals originating from directions of highly absorbent walls, and a longer RT60 time for reverberation signals originating from directions corresponding to acoustically more reflective materials. In this case, the reverberation is different for different directions. Summary of the invention

[0007] According to a first aspect, a method for generating a reverberant audio signal is provided, the apparatus comprising: obtaining at least one audio signal; obtaining at least one spatial room impulse response; determining at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configuring at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in at least one spatial direction; and generating at least one reverberant audio signal based on the configured at least one reverberator and the at least one audio signal.

[0008] Based on at least one spatial room impulse response, determining at least one parameter may include: determining a common decay rate parameter, wherein, based on the determined at least one parameter, configuring at least one reverberator may include: determining a common decay rate of at least one delay line decay filter for the at least one reverberator based on the common decay rate parameter and at least one dimension of the at least one acoustic environment.

[0009] Determining a common decay rate parameter may include determining the common decay rate parameter based at least in part on an omnidirectional component of at least one spatial room impulse response.

[0010] Determining a common attenuation rate parameter may include: determining an energy attenuation curve based on an omnidirectional component of at least one spatial room impulse response; determining noise power based on at least one spatial room impulse response; determining a denoised energy attenuation curve based on the determined energy attenuation curve and noise power; and determining a common attenuation rate parameter based on the denoised energy attenuation curve.

[0011] Based on the at least one spatial room impulse response, determining at least one parameter may include further determining at least one of: determining a pre-delay time based on the at least one spatial room impulse response; and determining an initial gain parameter based on a denoised energy decay curve at the pre-delay time.

[0012] Based on at least one spatial room impulse response, determining the pre-delay time may include: determining the diffuseness of the at least one spatial room impulse response; averaging the diffuseness over the frequency of the at least one spatial room impulse response; and determining a time at which the average value of the diffuseness exceeds a determined threshold, wherein the time is the pre-delay time.

[0013] Based on at least one spatial room impulse response, determining at least one parameter may include: determining a direct sound peak within the at least one spatial room impulse response; applying windowing to the direct sound peak to determine an omnidirectional energy of the at least one spatial room impulse response and an energy of the direct sound pulse; and determining a reverberation to direct ratio based on the omnidirectional energy of the at least one spatial room impulse response and the energy of the direct sound pulse.

[0014] Configuring the at least one reverberator based on the determined at least one parameter may include: determining at least one beamforming impulse response for a spatial direction associated with an output channel direction of the at least one reverberator based on the at least one spatial room impulse response; determining a parameter for the at least one spatial direction based on the at least one beamforming impulse response; and determining at least one output channel gain coefficient of the at least one reverberator based on the at least one parameter.

[0015] Obtaining at least one spatial room impulse response may include obtaining an Ambisonic impulse response measured in at least one acoustic environment.

[0016] Determining at least one beamforming impulse response for a spatial direction associated with an output channel direction of at least one reverberator based on the at least one spatial room impulse response may include determining the beamforming impulse response based on applying spherical harmonics in at least one determined loudspeaker direction applied to the at least one spatial room impulse response.

[0017] Based on at least one beamforming impulse response, determining at least one parameter for at least one spatial direction may include: determining an energy attenuation curve based on at least one beamforming impulse response; determining noise power based on at least one beamforming impulse response; determining a denoised energy attenuation curve based on the determined energy attenuation curve and noise power; and determining a directional attenuation parameter based on the denoised energy attenuation curve.

[0018] Based on the at least one spatial room impulse response, determining the at least one parameter may include: obtaining another pre-delay time; and determining another initial gain parameter based on a denoised energy decay curve at the another pre-delay time.

[0019] Based on the at least one spatial room impulse response, determining at least one parameter may include determining at least one directional gain based on the normalized further initial gain parameter.

[0020] Another pre-delay time may be the pre-delay time.

[0021] The at least one audio signal may be associated with at least one acoustic environment, and wherein the at least one spatial room impulse response may be defined by the at least one acoustic environment.

[0022] The at least one parameter may include at least one directional attenuation parameter for at least one spatial direction within at least one acoustic environment.

[0023] According to a second aspect, there is provided an apparatus for generating a reverberant audio signal, the apparatus comprising components configured to: obtain at least one audio signal; obtain at least one spatial room impulse response; determine at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configure at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in at least one spatial direction; and generate at least one reverberant audio signal based on the configured at least one reverberator and the at least one audio signal.

[0024] The component configured to determine at least one parameter based on at least one spatial room impulse response may be configured to determine a common decay rate parameter, wherein the component configured to configure at least one reverberator based on the determined at least one parameter may be configured to determine a common decay rate of at least one delay line decay filter for the at least one reverberator based on the common decay rate parameter and at least one dimension of at least one acoustic environment.

[0025] The component configured to determine the common decay rate parameter may be configured to determine the common decay rate parameter based at least in part on an omnidirectional component of the at least one spatial room impulse response.

[0026] The component configured to determine a common attenuation rate parameter can be configured to: determine an energy attenuation curve based on the omnidirectional component of at least one spatial room impulse response; determine the noise power based on at least one spatial room impulse response; determine a denoised energy attenuation curve based on the determined energy attenuation curve and the noise power; and determine the common attenuation rate parameter based on the denoised energy attenuation curve.

[0027] The component configured to determine at least one parameter based on at least one spatial room impulse response can be configured to further determine at least one of the following: determining a pre-delay time based on the at least one spatial room impulse response; and determining an initial gain parameter based on a denoised energy decay curve at the pre-delay time.

[0028] The component configured to determine the pre-delay time based on at least one spatial room impulse response can be configured to: determine the diffuseness of the at least one spatial room impulse response; average the diffuseness over the frequency of the at least one spatial room impulse response; and determine the time when the average value of the diffuseness exceeds a determined threshold, wherein the time is the pre-delay time.

[0029] The component configured to determine at least one parameter based on at least one spatial room impulse response can be configured to: determine a direct sound peak within the at least one spatial room impulse response; apply windowing to the direct sound peak to determine an omnidirectional energy of the at least one spatial room impulse response and an energy of the direct sound pulse; and determine a reverberation to direct ratio based on the omnidirectional energy of the at least one spatial room impulse response and the energy of the direct sound pulse.

[0030] The component configured to configure the at least one reverberator based on the determined at least one parameter may be configured to: determine at least one beamforming impulse response for a spatial direction associated with an output channel direction of the at least one reverberator based on the at least one spatial room impulse response; determine a parameter for the at least one spatial direction based on the at least one beamforming impulse response; and determine at least one output channel gain coefficient of the at least one reverberator based on the at least one parameter.

[0031] The component configured to obtain at least one spatial room impulse response may be configured to obtain an Ambisonic impulse response measured in at least one acoustic environment.

[0032] The component configured to determine at least one beamforming impulse response for a spatial direction associated with an output channel direction of at least one reverberator based on at least one spatial room impulse response can be configured to: determine the beamforming impulse response based on applying spherical harmonics in at least one determined loudspeaker direction applied to the at least one spatial room impulse response.

[0033] A component configured to determine at least one parameter for at least one spatial direction based on at least one beamforming impulse response can be configured to: determine an energy attenuation curve based on at least one beamforming impulse response; determine noise power based on at least one beamforming impulse response; determine a denoised energy attenuation curve based on the determined energy attenuation curve and noise power; and determine a directional attenuation parameter based on the denoised energy attenuation curve.

[0034] The component configured to determine at least one parameter based on at least one spatial room impulse response may be configured to: obtain another pre-delay time; and determine another initial gain parameter based on a denoised energy decay curve at the another pre-delay time.

[0035] The component configured to determine at least one parameter based on at least one spatial room impulse response may be configured to determine at least one directional gain based on the normalized further initial gain parameter.

[0036] Another pre-delay time may be the pre-delay time.

[0037] The at least one audio signal may be associated with at least one acoustic environment, and wherein the at least one spatial room impulse response may be defined by the at least one acoustic environment.

[0038] The at least one parameter may include at least one directional attenuation parameter for at least one spatial direction within at least one acoustic environment.

[0039] According to a third aspect, there is provided an apparatus for generating a reverberant audio signal, the apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the system to at least perform: obtaining at least one audio signal; obtaining at least one spatial room impulse response; determining at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configuring at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in at least one spatial direction; and generating at least one reverberant audio signal based on the configured at least one reverberator and the at least one audio signal.

[0040] The device caused to determine at least one parameter based on at least one spatial room impulse response may be further caused to perform: determining a common decay rate parameter, wherein the device caused to configure at least one reverberator based on the determined at least one parameter is caused to perform: determining a common decay rate of at least one delay line decay filter for the at least one reverberator based on the common decay rate parameter and at least one dimension of at least one acoustic environment.

[0041] The apparatus caused to determine a common decay rate parameter may be further caused to perform: determining the common decay rate parameter based at least in part on an omnidirectional component of at least one spatial room impulse response.

[0042] The device that is configured to determine the common attenuation rate parameter can be further configured to perform: determining an energy attenuation curve based on the omnidirectional component of at least one spatial room impulse response; determining the noise power based on at least one spatial room impulse response; determining a denoised energy attenuation curve based on the determined energy attenuation curve and the noise power; and determining the common attenuation rate parameter based on the denoised energy attenuation curve.

[0043] The device, which is caused to determine at least one parameter based on at least one spatial room impulse response, can be further caused to perform at least one of the following: determining a pre-delay time based on at least one spatial room impulse response; and determining an initial gain parameter based on a denoised energy decay curve at the pre-delay time.

[0044] The device that is caused to determine the pre-delay time based on at least one spatial room impulse response can be caused to perform: determining the diffuseness of the at least one spatial room impulse response; averaging the diffuseness over the frequency of the at least one spatial room impulse response; and determining the time when the average value of the diffuseness exceeds a determined threshold, wherein the time is the pre-delay time.

[0045] The device, which is caused to determine at least one parameter based on at least one spatial room impulse response, can be further caused to perform: determining a direct sound peak within the at least one spatial room impulse response; applying windowing to the direct sound peak to determine the omnidirectional energy of the at least one spatial room impulse response and the energy of the direct sound pulse; and determining a reverberation to direct ratio based on the omnidirectional energy of the at least one spatial room impulse response and the energy of the direct sound pulse.

[0046] The apparatus caused to configure at least one reverberator based on the determined at least one parameter may be caused to perform: determining at least one beamforming impulse response for a spatial direction associated with an output channel direction of the at least one reverberator based on the at least one spatial room impulse response; determining a parameter for at least one spatial direction based on the at least one beamforming impulse response; and determining at least one output channel gain coefficient of the at least one reverberator based on the at least one parameter.

[0047] The apparatus caused to obtain at least one spatial room impulse response may further be caused to perform: obtaining an Ambisonic impulse response measured in at least one acoustic environment.

[0048] The apparatus being caused to determine, based on at least one spatial room impulse response, at least one beamforming impulse response for a spatial direction associated with an output channel direction of at least one reverberator may further be caused to perform: determining the beamforming impulse response based on applying spherical harmonics in at least one determined loudspeaker direction applied to the at least one spatial room impulse response.

[0049] The device, which is enabled to determine at least one parameter for at least one spatial direction based on at least one beamforming impulse response, can be enabled to perform: determining an energy attenuation curve based on at least one beamforming impulse response; determining noise power based on at least one beamforming impulse response; determining a denoised energy attenuation curve based on the determined energy attenuation curve and noise power; and determining a directional attenuation parameter based on the denoised energy attenuation curve.

[0050] The apparatus caused to determine at least one parameter based on at least one spatial room impulse response may be further caused to perform: obtaining another pre-delay time; and determining another initial gain parameter based on a denoised energy decay curve at the another pre-delay time.

[0051] The apparatus caused to determine at least one parameter based on at least one spatial room impulse response may be caused to perform: determining at least one directional gain based on the normalized further initial gain parameter.

[0052] Another pre-delay time may be the pre-delay time.

[0053] The at least one audio signal may be associated with at least one acoustic environment, and wherein the at least one spatial room impulse response may be defined by the at least one acoustic environment.

[0054] The at least one parameter may include at least one directional attenuation parameter for at least one spatial direction within at least one acoustic environment.

[0055] According to a fourth aspect, there is provided an apparatus for generating a reverberant audio signal, the apparatus comprising: an obtaining circuit configured to obtain at least one audio signal; an obtaining circuit configured to obtain at least one spatial room impulse response; a determining circuit configured to determine at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; a configuring circuit configured to configure at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in at least one spatial direction; and a generating circuit configured to generate at least one reverberant audio signal based on the configured at least one reverberator and at least one audio signal.

[0056] According to a fifth aspect, there is provided a computer program [or a computer-readable medium] comprising instructions, the instructions being used to cause an apparatus to generate a reverberant audio signal, the apparatus being caused to perform at least the following operations: obtain at least one audio signal; obtain at least one audio signal; obtain at least one spatial room impulse response; determine at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configure at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in at least one spatial direction; and generate at least one reverberant audio signal based on the configured at least one reverberator and the at least one audio signal.

[0057] According to a sixth aspect, there is provided a non-transitory computer-readable medium comprising program instructions for causing at least one device for generating a reverberant audio signal to perform the following operations: obtain at least one audio signal; obtain at least one spatial room impulse response; determine at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configure at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in at least one spatial direction; and generate at least one reverberant audio signal based on the configured at least one reverberator and the at least one audio signal.

[0058] According to a seventh aspect, there is provided an apparatus for generating a reverberant audio signal, comprising: a component for obtaining at least one audio signal; a component for obtaining at least one spatial room impulse response; a component for determining at least one parameter based on the at least one spatial room impulse response, wherein the at least one parameter is for at least one spatial direction; a component for configuring at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in at least one spatial direction; and a component for generating at least one reverberant audio signal based on the configured at least one reverberator and at least one audio signal.

[0059] According to an eighth aspect, there is provided a computer-readable medium comprising instructions for causing an apparatus for generating a reverberant audio signal to perform at least the following operations: obtain at least one audio signal; obtain at least one spatial room impulse response; determine at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configure at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in at least one spatial direction; and generate at least one reverberant audio signal based on the configured at least one reverberator and at least one audio signal.

[0060] An apparatus comprises means for performing the actions of the method as described above.

[0061] A device is configured to perform the actions of the method described above.

[0062] A computer program comprises instructions for causing a computer to execute the method as described above.

[0063] A computer program product stored on a medium may cause an apparatus to perform the method described herein.

[0064] An electronic device may include an apparatus as described herein.

[0065] A chipset may include the apparatus as described herein.

[0066] The embodiments of the present application are intended to solve the problems associated with the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] For a better understanding of the present application, reference will now be made by way of example to the accompanying drawings, in which:

[0068] Figure 1 Shows a model of room acoustics and room impulse response;

[0069] Figure 2 schematically illustrates example apparatus in which some embodiments may be implemented;

[0070] Figure 3 Shown as Figure 2 A flowchart of the operation of the example apparatus shown in;

[0071] Figure 4 Schematically illustrating how Figure 2 The example reverberator parameter determiner shown in ;

[0072] Figure 5 According to some embodiments, Figure 4 A flowchart of the operation of an example reverberator parameter determiner shown in;

[0073] Figure 6 An example determination of a pre-delay based on a running estimate of diffusivity exceeding a predetermined threshold or level is shown;

[0074] Figure 7 An example of analyzing RT60 and initial gain according to the energy decay function of an omnidirectional room impulse response is shown;

[0075] Figure 8 Schematically illustrating how Figure 2 The example directional gain determiner shown in ;

[0076] Fig. 9 Shown as Figure 8 A flowchart of the operation of an example directional gain determiner shown in;

[0077] Fig.10 An example of modeling spatial non-uniform reverberation using uniform attenuation with different gain levels is shown;

[0078] Fig.11 Schematically illustrating how Figure 2 The example reverb shown in ;

[0079] Fig.12 It shows that Fig.11 A flowchart of the operation of the example reverberator shown in;

[0080] Fig.13 Schematically illustrating how Fig.11 The example FDN reverb shown in;

[0081] Fig.14 Show Fig.12 A flowchart of the operation of an example reverberator controller as shown in;

[0082] Fig.15 Schematically illustrating how Figure 2 The example binaural renderer shown in ;

[0083] Fig.16 Shown as Fig.15 A flowchart of the operation of an example binaural renderer shown in ;

[0084] Fig.17 schematically illustrates an example apparatus with transmission and / or storage in which some embodiments may be implemented; and

[0085] Fig.18 An example apparatus suitable for implementing the means shown in the preceding Figures is shown. DETAILED DESCRIPTION

[0086] Suitable apparatus and possible mechanisms for parameterizing and rendering audio scenes with reverberation are described in further detail below.Thus, for example, suitable apparatus and methods may be part of spatial audio rendering (also referred to as spatial rendering).

[0087] As discussed above, reverberation can be rendered using, for example, a Feedback Delay Network (FDN) reverberator (with appropriately adjusted delay line lengths). FDN allows for individual control of the reverberation time (RT60) and the energy of different frequency bands. Thus, it can be used to render reverberation based on the characteristics of a room or modeled space. The reverberation time and the energy of different frequencies are affected by the frequency-dependent absorption characteristics of the room.

[0088] In the case of a room with a completely diffuse late reverberation, the reverberation characteristics are the same in any direction. In this case, the same acoustic characteristics can be used to adjust the different channels of, for example, an FDN reverberator.

[0089] Known methods using impulse responses can be used to derive such acoustic properties, for example, using an omnidirectional impulse response. However, in real life, the late reverberation in a room is rarely completely diffuse. Instead, the late reverberation is different for different directions.

[0090] However, setting the late reverb to be the same in all directions may produce an "unrealistic" effect and therefore reduce the quality of the rendering. In particular in the case of AR renderings, it is desirable to produce a realistic rendering of the late reverb in order to achieve a seamless perception of the real sound sources in the room and the augmented audio sources being rendered to the listener.

[0091] If the late reverberation in the room is not equal in all directions, there will be a difference between the perception of real sources (which have unequal directional characteristics in the late reverberation) and enhanced sources (which have equal directional characteristics in all directions).

[0092] Another proposed option is to determine the absorption coefficients of all surfaces in the room and use these coefficients to determine direction-dependent acoustic properties. This is a viable option for VR renderings, where the content creator can manually set the required information and / or can use offline encoder processing to perform computationally intensive acoustic simulations to use the absorption coefficients to produce a spatial room impulse response. However, this is not a suitable option for a system that automatically obtains the information. For example, in AR renderings, the required information is automatically obtained using impulse responses in order to allow a user device to capture the acoustic properties of the room in which the device is located and realistically bring augmented audio sources into the space.

[0093] Another possible option is to analyze the different reverberation characteristics in different directions of the room. However, this approach may lack the possibility to configure the digital reverberator based on the analysis or the way to render the reverberation for the listener. In addition, some known methods propose ways to use digital reverberators to render non-uniform reverberation characteristics to different spatial directions, but these methods are computationally intensive.

[0094] Therefore, the aim is to automatically obtain (e.g. using impulse responses) directional reverberation characteristics, and computationally efficiently use these directional reverberation characteristics to render a reverberation that matches the (directional) reverberation characteristics of a (real) room. This avoids the need to discard these directional characteristics (which makes rendering unrealistic), and also avoids the need to manually adjust the reverberator characteristics (which prevents use in systems that require automatic operation (such as AR rendering)).

[0095] Concepts as discussed in further detail in embodiments herein relate to the reproduction of (late) reverberation, wherein a method (an apparatus configured to implement the method) is proposed that enables automatic capture of (directional) reverberation characteristics using an impulse response of a (physical) room and reverberation rendering using the captured characteristics, such that the characteristics (including directional characteristics) of the rendered reverberation are related to the reverberation characteristics of the (physical) room. In some embodiments, this may be achieved by obtaining a spatial room impulse response (SRIR), determining a directional attenuation parameter for at least one spatial direction using the SRIR based on the determined at least one directional attenuation parameter, adjusting a reverberator so as to control the output in the corresponding direction, and further rendering a reverberated signal using the reverberator and at least one input signal.

[0096] In some embodiments, a feedback delay network (FDN) reverberator with N output channels is used. The output channels are associated with N spatial directions around the listener. The output of the reverberator can be reproduced using (virtual or real) speakers in the corresponding directions. In one example, N can be 15. Other suitable values ​​for N can be, for example, 7, 8, 16, 31, 32, 63, 64.

[0097] In these embodiments, the input SRIR may be an Ambisonic impulse response measured in a room (acoustic space). First, using the omnidirectional component of the SRIR, a common decay rate parameter is estimated. Then, the common decay rate of the delay line decay filters (of all channels) used for the FDN is adjusted using the common decay parameter and at least one size parameter associated with the room.

[0098] Next, the SRIR is used to determine the beamforming impulse response for the spatial direction (corresponding to the output channel direction of the FDN). Using the beamforming impulse response, the directional attenuation parameter is determined for the spatial direction. Then, the output channel gain coefficient of the FDN reverberator is adjusted by the corresponding directional attenuation parameter.

[0099] Finally, the input audio signal can be reverberated using the adapted FDN reverberator. As output, there are 15 (in this example) mutually (almost) incoherent reverberation signals. The output signals can be reproduced using loudspeakers (or alternatively virtual loudspeakers convolved with the HRTF) that are located in directions corresponding to the spatial directions used above and controlled using channel gain coefficients.

[0100] The resulting reverberation is perceived as having reverberation characteristics that match the room in which the SRIR was captured. Furthermore, the directional characteristics of the reverberation match the room because the attenuation characteristics of the output channels are controlled using output channel gain coefficients that are adjusted based on the directional attenuation parameters. Furthermore, since the FDN reverberator is computationally efficient and rendering the directional reverberation characteristics requires only applying a gain on the output channels, directional reverberation processing can be performed with very low computational complexity.

[0101] Note that this method does not explicitly attempt to adjust the directional attenuation of the reverberation output to match the analyzed directional attenuation. Instead, the directional attenuation level is adjusted based on the analyzed directional attenuation parameters. The benefit of this is reduced computational complexity, since different spatial directions do not require different reverberators with different attenuations. This method also achieves the purpose of producing the desired perceptual target, which has a non-uniform power distribution of late energy towards different spatial directions, since the level of reverberation is different for different spatial directions, even if the attenuation (RT60) characteristics are shared by different spatial directions.

[0102] The proposed embodiments are particularly useful for augmented reality (AR) audio rendering, as it can automatically determine the required information using only the impulse response and room dimensions, without the need for manual adjustment of reverberation parameters. Furthermore, the embodiments as discussed herein can be modified without much effort for other use cases, such as virtual reality (VR) audio rendering, where the embodiments can provide the same advantage of automatically determining the required parameters (to provide / model virtual room reverberation characteristics based on captured or simulated SRIR input to the system).

[0103] Figure 2 A schematic diagram of an example apparatus suitable for implementing some embodiments is shown. The example apparatus is configured to receive as input an audio signal 200, a spatial room impulse response (SRIR) 202, a speaker setup 204, and room dimensions 206. The apparatus is configured to render as output a reverberant binaural signal 214 containing late reverberation that is perceived the same as if the sound source was actually located in the room in which the spatial room impulse response 202 was measured. It should be noted that the apparatus is configured to show only the late reverberation rendering and that the direct sound and early reflection rendering will be considered separately and not described in further detail.

[0104] Space Room Impulse Response 202h SRIR (t,j) contains the impulse response with J channels measured in the room (where t is the time in samples and j is the impulse response channel). For example, the impulse response may be a channel of a (first or higher order) Ambisonic room impulse response (which may be obtained, for example, by measuring the impulse response using a dedicated microphone such as an Eigenmike).

[0105] In some embodiments, the apparatus comprises a reverberation parameter determiner 201 configured to receive a spatial room impulse response 201h SRIR (t, j). The reverberation parameter determiner is configured to determine suitable (non-directional) parameters 208 for configuring the reverberator 205. In some embodiments, the reverberation parameters 208 may include the reverberation time T in a frequency band 60 (k) (where k is the frequency band index), the total gain g0(k) in the frequency band, and the pre-delay d. The spatial room impulse response 202h may be used, for example SRIR The reverberation parameters 208 are determined by the omnidirectional component of (t, j).

[0106] In some embodiments, the apparatus further comprises a directional gain determiner 203. The directional gain determiner 203 is configured to receive or obtain a spatial room impulse response 202h SRIR (t, j) and speaker setup 204. Speaker setup 204 is a surrounding speaker setup that can be used to create a sense of surrounding diffuse reverberation. As an example, the following setup can be used:

[0107] Azimuth θ ls (i): 90, -90, 114, -60, 85, -130, 49, -67, 154, -48, 19, -162, 151, -9, 180 degrees.

[0108] Elevation angle φ ls (i): 0, 0, 20, -6, -44, -21, 41, 52, -9, -55, -31, 21, 733, 20, 63 degrees.

[0109] This arrangement is suitable when the number of output channels N is equal to 15. When the number of output channels is different, different arrangements may be used so that they adequately cover the directions around the listener.

[0110] Direction θ ls (i) φ ls (i) corresponds to the output channel i of the reverberator 205. Using the spatial room impulse response 202h SRIR(t, j), the directional gain determiner 203 is configured to determine the direction θ of the loudspeaker arrangement 204 ls (i) φ ls (i) Determine the directional gain of 210 g i (k) In some embodiments, the directional gain 210 may be determined based on a directional attenuation parameter determined from the spatial room impulse response 202 .

[0111] In some embodiments, the apparatus comprises a reverberator 205. The reverberator 205 is configured to receive a reverberation parameter 208T 60 (k), g0(k), d, directional gain 210 g i (k) and audio signal 200 s in (t). In some embodiments, the reverberator 205 may also receive the speaker settings 204 and the room dimensions 206, which may be used to optimize the reverberation (however, this is optional). In other words, the reverberator may be configured or adjusted based on the determined parameters. When this specification describes configuring a reverberator, such configuration may be considered a modification or adjustment of the reverberator.

[0112] In some embodiments, the reverberator 205 is implemented using a feedback delay network (FDN) reverberator. In this example embodiment, the FDN reverberator has N=15 output channels i. (However, any suitable number of channels may be used). The resulting directional reverberant audio signal 212 s re v(t,i) are mutually incoherent and have non-directional acoustic characteristics according to the reverberation parameter 208 and have directional acoustic characteristics according to the directional gain 210 .

[0113] In some embodiments, the apparatus further comprises a binaural renderer 207. In some embodiments, the binaural renderer 207 is configured to receive the directional reverberant audio signal 212 s rev (t,i), and also receives the speaker setting 204. The binaural renderer 207 is configured to render the reverberated audio signal to generate a reverberated binaural signal 214 s bin (n,i bin )(where i bin These reverberant binaural audio signals 214 are perceived as surround and enveloping, and are measured according to the spatial room impulse response 202 h SRIR The room (t,j) has both directional and non-directional acoustic properties.

[0114] about Figure 3 , showing a schematic diagram of a method according to some embodiments Figure 2 Flowchart of the operation of the example apparatus shown in .

[0115] The method may include obtaining an audio signal, a spatial room impulse response, a speaker setup (and optionally room dimensions), as indicated by 301 .

[0116] Then, as indicated by 303, reverberation parameters are determined.

[0117] Then, as indicated by 305, a directional gain is determined.

[0118] As indicated by 307 , reverberation is applied to the audio signal based on the reverberation parameters, directional gain, and optionally the room dimensions and speaker setup.

[0119] Then, as indicated by 309 , a binaural rendering of the reverberant binaural audio signal is generated based on the directional reverberant audio signal.

[0120] Furthermore, as indicated by 311 , a reverberant binaural audio signal is output.

[0121] about Figure 4 , an example reverberation parameter determiner 201 according to some embodiments is also shown in further detail.

[0122] The reverberation parameter determiner 201 is configured to receive a spatial room impulse response 202 .

[0123] In some embodiments, the reverberation parameter determiner 201 comprises a short time Fourier transform (STFT) 201, which receives the SRIR and generates a time-frequency domain room response 402. Thus, the SRIR is converted from h SRIR (t,j) is transformed into h SRIR (n,m,j), where n and m are the frame and frequency bin indices, respectively. The bin range is chosen to be above the modal range of the room response and below the spatial aliasing limit of the microphone array, e.g., from 1 kHz to 4-5 kHz.

[0124] Furthermore, the reverberation parameter determiner 201 comprises a direction of arrival (DOA) calculator 405 configured to receive the time-frequency domain room response 402 and generate a direction of arrival value 406. In some embodiments, DOA analysis is applied using a B-format signal as described in Jukka Ahonen, Ville Pulkki, “Diffuseness Estimation Using Temporal Variation of Intensity Vectors”, IEEE Symposium on Applications of Audio and Acoustic Signal Processing, New Paltz, NY, USA, October 18-21, 2009, pp. 337-340. However, in some alternative embodiments (particularly those using different microphone arrays), different DOA analysis methods may be used, such as the method described in Archontis Politis, Symeon Delikaris-Manias, Ville Pulcki, "Direction-of-arrival and diffuseness estimation above spatial aliasing for symmetrical directional microphone arrays," 2015 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)."

[0125] The reverberation parameter determiner 201 comprises a diffuseness value calculator 409 configured to obtain the direction of arrival value 406 and output a diffuseness value 410. The diffuseness value may be determined for a time-frequency bin (n, m) that is below the spatial aliasing limit of the array based on the temporal fluctuations of the short-time narrowband direction of arrival vector determined by the DOA calculator 403. The diffuseness estimation may use any suitable method, such as described in the above-mentioned references.

[0126] Furthermore, the reverberation parameter determiner 201 comprises a cross-frequency averager 413, which is configured to average the diffuseness values ​​410 across frequencies and generate an average diffuseness value 414. In the frequency averager 413, the narrowband diffuseness values ​​ψ(n,m) are further averaged across frequencies to obtain a broadband diffuseness value ψ bb (n).

[0127] The reverberation parameter determiner 201 also includes a level crossing determiner 417, which is configured to determine level crossings of the average diffuseness values ​​and output these level crossings 418. The average diffuseness value remains low in the early part of the SRIR and then rises as it transitions from the early part to the late part. The level crossing determiner is configured to determine when the average value crosses a suitable threshold (e.g., 0.8). Figure 6 , shows a graph of a room impulse response 601 , an average or broadband diffuseness value 603 , and an example threshold value 605 and the point 607 at which the broadband diffuseness value 602 crosses the threshold.

[0128] Furthermore, the reverberation parameter determiner 201 comprises a pre-delay estimator 421 which is configured to estimate a pre-delay value 422d based on the level crossing information 418. Thus, the pre-delay d is effectively calculated from the spatial RIR based on a running measure of diffuseness ψ = [0,1] which indicates how complex the spatial structure of the SRIR is in time (ranging from 0 for an isolated single broadband reflection to 1 for a structure that is a result of multiple incoherent echoes arriving from multiple directions, which is characteristic of late reverberation conditions). The mixing time is determined by when this value crosses a suitable threshold (e.g. 0.8).

[0129] Furthermore, in some embodiments, the reverberation parameter determiner 201 includes a filter bank 403 configured to receive the SRIR and decompose the SRIR into a plurality of sub-bands determined by the desired parameterization. In one example, the filter bank 403 is a suitable octave band filter bank, wherein the subset of octave band center frequencies is [125, 250, 500, 1000, 2000, 4000] Hz, and the SRIR is decomposed into six corresponding SRIRs 404 h SRIR (n, k, j), where k is the subband index. Furthermore, the rest of the parameters are calculated independently in the frequency bands, and for simplicity, the following process is described for one of the subbands.

[0130] The reverberation parameter determiner 201 includes an energy decay curve (EDC) calculator 407. The EDC calculator 407 is configured to receive the SRIR subband and determine the EDC 408 output. In the following example, the omnidirectional representation of the RIR (which may be the first channel of the B-format SRIR, h OMNI (n,k)=h SRIR (n,k,1)), the energy attenuation curve EDC(n,k) for a subband can be obtained by OMNI (n,k) is integrated backward to produce:

[0131] in,

[0132] Where N is the total length of the SRIR in the sample.

[0133] Furthermore, in some embodiments, the reverberation parameter determiner 201 comprises a noise power calculator 411. Since the input is the measured RIR, there is likely to be measurement noise in the response, which may bias the estimation of these parameters. The noise may come from the surrounding environment or from the microphone itself, and is assumed to be additive, stable, and uncorrelated with the clean RIR, which yields the following signal model:

[0134] EDC(n,k)=EDC RIR (n,k)+EDC noise (n,k)

[0135] Since the noise is assumed to be stationary, with a power per sample P noise (k), therefore, the modeled noise EDC is linear and is given by:

[0136] EDC noise (n,k)=(Nn)P noise (k)

[0137] The EDC of the RIRs is assumed to follow a weighted exponential decay type:

[0138]

[0139] The decay rate is given by:

[0140]

[0141] Since the RIR decays below the noise floor after a period of time, the noise EDC can be calculated over a certain late segment in the measurement (e.g., t>1 second in a normal room). In turn, it can be assumed that the EDC for this segment is dominated by the noise term, and a line can be fitted to extrapolate the noise EDC over the entire range of RIRs.

[0142] Therefore, the noise power calculator 411 may be configured to estimate the noise power 412 based on a later period in the measurement. Figure 7 It is shown in Figure 7 A first graph 700 shows an example RIR 702 and noise 704, and illustrates that the noise power P can be estimated in this example. in The noise-dominated area of ​​705.

[0143] The reverberation parameter determiner 201 may further include a noise EDC calculator 415 which calculates the noise EDC based on the noise power P in 412 is configured to determine the noise EDC (fit line) 416. This is for example Figure 7 is shown by line 708 on the second graph 720 .

[0144] Furthermore, the reverberation parameter determiner 201 comprises a denoised EDC calculator 419. The denoised EDC calculator 419 is configured to extract the noise from the noisy EDC values ​​(e.g. Figure 7 The noise EDC ( Figure 7 line 708) to generate the denoised EDC value 420 (as in Figure 7 In other words, the modeled noise EDC can be calculated by subtracting the EDC(n,k) calculated from the measured RIR. noise (n,k) to estimate the denoised EDC RIR (n,k):

[0145] EDC RIR (n,k)=EDC(n,k)-EDC noise (n,k)

[0146] The reverberation parameter determiner 201 includes an RT60 calculator 423. The RT60 calculator 423 may receive the denoised EDC value 420EDC RIR (n, k), and the EDC is expressed in decibels, where the exponential form is converted to a linear form (such as in Figure 7 In the third graph 730, line 733EDC db as shown and compared with a noisy EDC in linear form as shown by line 735).

[0147] Then, a line is fitted 711 to the denoised EDC, starting from a time point that avoids the early part (which typically deviates from the exponential model of the late part), for example, at -5dB to -10dB from the maximum value of the EDC. The end point can be taken at -20dB or -30dB from the first point, and the corresponding time interval between the two is multiplied by 3 or 2, respectively, to scale to RT60 717. The RT60 value 424 can be output.

[0148] Furthermore, the reverberation parameter determiner 201 comprises a delay rate calculator 425 which, knowing the RT60 value 424, can calculate a decay rate a(k) given by:

[0149]

[0150] The reverberation parameter determiner 201 may further include an initial gain calculator 427 configured to receive the decay rate 426 and the pre-delay 422 to determine an initial gain g by the denoised EDC value at the pre-delay d. 0,dB =20log 10 (g0). This is for example Figure 7The gain value g at the mixing time T_mix 751 on line 755 is 0,dB 753 is shown.

[0151] In some embodiments, the reverberation parameter determiner 201 comprises an RDR calculator, which is configured to determine an estimated reverberation-to-direct ratio (RDR) representing the total energy of the late reverberation relative to the energy of the direct sound, as an alternative or in addition to the initial gain. This can be estimated by the ratio of the omnidirectional energy of the impulse response measured after appropriate windowing to the energy of the direct sound pulse. After the direct sound peak is detected and windowed using, for example, a 5 ms window centered thereon, the direct sound energy is:

[0152]

[0153] Among them, n dir is the direct peak index, and D src is the source-receiver distance and is used to normalize the RDR to a 1m reference source-receiver distance. The late acoustic energy is the non-normalized EDC value at the mixing time:

[0154] E late (k)=DF(k)EDC RIR (d,k),

[0155] Where DF(k) is the source directivity factor (if known) used to compensate the RDR to the omnidirectional reference case. In some embodiments where the source directivity is unknown, its value can be set to 1, DF(k) = 1. Finally, the total broadband RDR is given by:

[0156]

[0157] In some embodiments, the RDR may be converted to a diffusion to source energy ratio or other reverberation ratio parameter. The output of the reverberation parameter determiner 201 is the reverberation parameters 200 , which may include RT60 451 , decay rate 453 , pre-delay 455 , initial gain 457 , and RDR 459 .

[0158] about Figure 5 , showing that Figure 4 Flowchart of the operation of an example reverberation parameter determiner 201 is shown in FIG.

[0159] As indicated by 501, a SRIR is obtained or otherwise received.

[0160] Then, as indicated by 503, a short time Fourier transform (STFT) may be performed on the SRIR.

[0161] As shown by 505, a DOA or intensity vector determination is used.

[0162] As indicated by 507 , a diffusivity value is determined or calculated.

[0163] As indicated by 509, the diffuseness values ​​are averaged to generate a broadband diffuseness value.

[0164] Then, as indicated by 511 , a level crossing between the broadband diffuseness value and the determined threshold is detected.

[0165] Then, as indicated by 513 , based on the level crossing, a pre-delay value is estimated.

[0166] Furthermore, in parallel with the STFT, a filter bank may be applied to the SRIR to determine a plurality of sub-band SRIR values, as indicated by 502 .

[0167] Then, as indicated by 504, an EDC may be calculated for the subband.

[0168] Additionally, as indicated by 506, noise power associated with the subband may also be determined.

[0169] Then, as indicated by 508, a denoised EDC may be determined or calculated.

[0170] Furthermore, as indicated by 510 , RT60 may be calculated based on the denoised EDC.

[0171] As indicated by 512 , a decay rate may be determined or calculated based on the estimated RT60 .

[0172] Then, as indicated by 515 , an initial gain may be determined based on the decay rate and the pre-delay value, and further, optionally or alternatively, an RDR may be calculated, as indicated by 517 .

[0173] Furthermore, as indicated by 519, reverberation parameters may be output.

[0174] about Figure 8 , showing that Figure 2 . The directional gain determiner 203 is configured to use the processing of the reverberation parameter determiner 201 to analyze the directional gain according to the beamforming SRIR. Therefore, the directional gain determiner 203 is configured to calculate the directional gain g for the direction for the part of the reverberation concentrated around the direction of the loudspeaker based on the similar EDC analysis as described above. i .

[0175] In some embodiments, the directional gain determiner 203 includes a beamformer 801. The beamformer 801 is configured to receive the spatial room impulse response (SRIR) 202 and the speaker direction 204, and calculate a beamforming impulse response for the direction of the speaker i in the speaker direction 204. For example, in some embodiments, the operation is based on beamforming using an Ambisonic signal, which is represented as:

[0176]

[0177] Among them, Y j are real spherical harmonics ordered using the ACN Ambisonic order, and w j are the ambisonic order-dependent weights that control the shape of the beamformer (e.g., cardioid, hypercardioid, or supercardioid patterns).

[0178] After the beamformed SRIRs 802 have been obtained, they are forwarded to a reverberation parameter determiner 803 .

[0179] In addition, the directional gain determiner 203 also includes a reverberation parameter determiner 803, which receives the beamformed SRIR 802. In some embodiments, the reverberation parameter determiner 803 may operate in the same manner as provided above for the omnidirectional component (including the same EDC calculation and denoising process), but the processing is applied to the beamformed response h SRIR (n, k, i) rather than an omnidirectional response. In some embodiments, the directional gain determiner 203 is configured to determine the predelay or beamformed predelay value in a similar manner as described above but with respect to the beamformed SRIR. However, in some embodiments, the predelay value used is the predelay value determined using the SRIR as described above.

[0180] Thus, the reverberation parameter determiner 803 may be configured to generate parameters 804, such as EDC RIR (n,k,i) and initial power value g′ i,dB .

[0181] In some embodiments, the reverberation parameter determiner 803 further includes an initial power value normalizer 805. The initial power value normalizer 805 is configured to receive the EDC RIR (n,k,i) and initial power value g′ i,dB parameters and normalize the values ​​around their mean dB values, such as:

[0182]

[0183] And its linear version Applied to FDN output.

[0184] Using directional gain 210 simplifies reverberation modeling and rendering. Fig.10 An example is shown in which Fig.10 The first graph 1001 of, for example, shows modeling of spatial non-uniform reverberation with, for example, different attenuation for different directions (as shown by different gradients and initial gains for the solid, dashed and dotted lines representing different directions). The second graph 1003 shows simplified modeling of spatial non-uniform reverberation with uniform attenuation for different directions (as shown by the same gradient but different initial gain values ​​for the solid, dashed and dotted lines representing different directions).

[0185] about Fig. 9 , a flow chart showing the operation of an example directional gain determiner according to some embodiments.

[0186] For example, as shown by 901, the operation of obtaining SRIR and speaker direction is shown.

[0187] Then, as shown by 903, the SRIR is beamformed based on the speaker direction.

[0188] As indicated by 905, reverberation parameters are determined.

[0189] Furthermore, as shown in 907, the initial power value is normalized.

[0190] Furthermore, as indicated by 909, a directional gain is output.

[0191] about Fig.11 , further details are shown as Figure 2 Schematic diagram of the reverberator 205 shown in .

[0192] In some embodiments, the reverberator includes a reverberation controller 1101. The reverberator controller 1101 is configured to receive or otherwise obtain reverberation parameters, room dimensions, and speaker settings, and in this example, uses reverberator parameters 1102 to initialize the FDN reverberator 1103.

[0193] Furthermore, the reverberator comprises a FDN reverberator 1103. The FDN reverberator 1103 is configured to receive reverberator parameters and, based on these reverberator parameters, control the reverberation applied to the audio signal 200 to generate a directional reverberant audio signal 202.

[0194] Fig.13 An example FDN reverberator 1103 is shown in more detail and may be used to generate D incoherent output audio signals.

[0195] The example FDN reverberator is configured such that the reverberation parameters are processed to generate the coefficients GEQ of the attenuation filter 1361 d (GEQ1, GEQ2, ...GEQ D ), the coefficient A of the feedback matrix 1357, the length md (m1, m2, ...m D ) and DDR energy ratio control filter 1353 coefficient GEQ ddr The DDR energy ratio control filter may also be referred to as an RDR energy ratio control filter or a reverberation ratio control filter or a reverberation equalization or coloring filter. The purpose of such a filter is to adjust the level and spectrum according to the RDR or other reverberation ratio data. Thus, the example FDN reverberator demonstrates a D channel output by providing the output from the FDN delay line as a separate output.

[0196] In some embodiments, the attenuation filter GEQ d 1361 is implemented as a graphic EQ filter using M biquad IIR band filters. Therefore, in the case of octave band M=10, the parameters of the graphic EQ include feedforward and feedback coefficients for the biquad IIR filter, gain for the biquad band filter, and total gain.

[0197] The reverberator generates a very dense impulse response for the late part using a network of delays 1359, feedback elements (shown as attenuation filters 1361, feedback matrix 1357, combiner 1355, and output gain 1363. Input samples are input to the reverberator to produce a reverberated audio signal component which can then be output.

[0198] The FDN reverberator includes a plurality of recirculating delay lines. A unitary matrix A 1357 is used to control the recirculation in the network. Attenuation filters 1361 (which in some embodiments may be implemented as a graphic EQ filter implemented as a cascade of second-order-section IIR filters) may facilitate controlling the rate of energy decay at different frequencies. The filters 1361 are designed so that they attenuate the desired amount (in decibels) of pulses as they pass through the delay lines and so that the desired RT60 time is obtained.

[0199] Thus, in the case of octave bands M=10, the parameters of the graphic EQ include the feedforward b and feedback a coefficients of the 10 biquad IIR filters, the gains for the biquad band filters, and the overall gain.

[0200] The number of delay lines D can be adjusted according to the quality requirements and the desired trade-off between reverberation quality and computational complexity. In an embodiment, an efficient implementation with D=15 delay lines is used. This makes it possible to define the feedback matrix coefficients A as proposed by Rocchesso in "Maximally Diffusive Yet Efficient Feedback Delay Networks for Artificial Reverberation", IEEE Signal Processing Letters, Vol. 4, No. 9, September 1997, in terms of Galois sequences that facilitate efficient implementations.

[0201] For this reverberator, the reverberator parameters contain the coefficients of the decay filter GEQ d 1361, the feedback matrix coefficient A1357, and the length m of the D delay lines 1359 d In addition, diffuse to direct ratio filter GEQ DDR In the present invention, the attenuation filter GEQ d is a graphic EQ filter using M biquad IIR band filters.

[0202] Thus, in the case of octave bands M = 10, the parameters of the graphic EQ include the feedforward and feedback coefficients for the 10 biquad IIR filters, the gain for the biquad band filters, and the overall gain. These parameters also include the pre-delay line z -mPre 1301 mPre and output channel gain c i 363.

[0203] Further described herein is Fig.11 A flow chart of the operation of the reverberator controller is shown in FIG.

[0204] First, reverberation parameters, room dimensions, speaker settings, and directional gains are obtained, as shown by 1400 .

[0205] Then, based on the room dimensions, the delay line length may be determined, as shown by 1401. For example, a shoebox-shaped room may be defined by dimensions xDim, yDim, zDim. If the room is not shoebox-shaped (rectangular), a shoebox may be placed into the room, and the dimensions of the placed shoebox may be used to obtain the delay line length. Alternatively, these dimensions may be obtained as the three longest dimensions in a non-shoebox-shaped room, or using other suitable methods.

[0206] Furthermore, as shown by 1403, the delay line attenuation filter gain is determined based on the delay line length and RT60(k). The attenuation filter coefficients in the delay line are adjusted so that the desired amount of attenuation (in decibels) occurs when the signal is recirculated through the delay line, thereby obtaining the desired RT60 time. This is achieved in a frequency-specific manner to ensure the appropriate attenuation rate of the signal energy at the specified frequency. For example, with respect to frequency k, the expected attenuation per signal sample is calculated as attenuationPerSample(k) = -60 / (sampling rate*rt60(k)). The length is m d The decibel attenuation of the delay line is then Db(k) = m d *attenuationPerSample(k)The expected attenuation per signal sample is calculated as attenuationPerSample(k)=-60 / (samplingRate*rt60(k)). d The attenuation (in decibels) of the delay line is attenuationDb(k)=m d *attenuationPerSample(k).

[0207] The roll-off filter is designed as a cascaded graphic equalizer filter for the delay line, as in V. and J. Liski, “Accurate cascade graphic equalizer”, IEEE Signal Processing Letters, Vol. 24, No. 2, pp. 176–180, February 2017. The design process outlined in the above references takes as input a set of command gains in octave bands. There are also methods for similar graphic EQ structures that can support three octave bands, thereby increasing the number of biquad filters to 31 and providing a better match for the detailed target response, such as in “Third-Octave and Bark Graphic-Equalizer Design with Symmetric Band Filters”. https: / / www.mdpi.com / 2076-3417 / 10 / 4 / 1222 / pdf In alternative embodiments, other suitable filters may be used, such as a polynomial IIR filter or a FIR filter.

[0208] Furthermore, based on the overall gain or reverberation ratio parameter, a reverberation ratio control filter parameter may be obtained, as indicated by 1405. The filter is designed so that when the filter is applied to the input data of the FDN reverberator, the output reverberation will have a desired energy ratio defined by RDR(k). The input to the design process is the RDR value RDR(k) obtained by the reverberation parameter determiner.

[0209] GEQ DDR The reverberator spectral energy is matched to a target spectral energy. To this end, an estimate of the RDR of the reverberator output and a target RDR are obtained. The RDR of the reverberator output may be obtained by rendering a unit pulse through the reverberator using a first reverberator parameter, measuring an energy of the reverberator output and an energy of the unit pulse, and calculating a ratio of these energies.

[0210] Create a unit pulse input where the first sample value is 1 and the length of the zero tail is sufficiently long. In practice, the length of the zero tail is adjusted to be equal to max(RT60(k)) plus d in samples. The mono output of the reverberator can be used to adjust the overall gain or energy, summing over the delay line j to obtain the reverberator output s as a function of time t rev (t).

[0211] In s rev The long FFT (length is NFFT) is calculated on (t), and its absolute value is obtained as:

[0212] FFA(kk)=abs(FFT(s rev (t))

[0213] Here, kk is the FFT bin index. In addition, we also obtain the positive half-spectrum energy density as:

[0214] S(kk)=1 / NFFT*FFA(kk) 2

[0215] Here, the energy from the negative frequency index kk is added to the corresponding positive frequency index kk.

[0216] The energy per unit pulse can be calculated or obtained analytically and is denoted as Su(kk).

[0217] Calculate the band energy of the reverberator's positive half-spectrum energy density S(kk) and the unit pulse's positive half-spectrum energy density Su(kk). The band energy can be calculated as:

[0218]

[0219] Among them, b low and b highare the lowest and highest bin indices belonging to frequency band b, respectively. The frequency band bin index can be obtained by comparing the frequency of the bin with the lower and upper bound frequencies of the frequency band.

[0220] Reproduction RDR of the reverberator output at frequency band k rev (k) can be obtained as:

[0221] RDR rev (k) = S(k) / Su(k)

[0222] GEQ RDR The target linear magnitude response can be obtained as:

[0223] rdrFilterTargetResponse(k)=sqrt(RDR(k)) / sqrt(RDR rev (k))

[0224] where RDR(b) is the linear target RDR value at frequency band k.

[0225] GontrolGain(k)=20*log10(rdrFilterTargetResponse(k)) is input as the target response (control gain) for the graphic equalizer design routine as in the above cited reference.

[0226] The RDR filter target response (control gain for the graphic EQ design routine) can also be obtained directly in the logarithmic domain as:

[0227] ControlGain(k)=10log 10 (RDR(k))-10log 10 (RDR rev (k))

[0228] Then, as shown by 1407, based on the pre-delay and the delay line length, the delay of the pre-delay line is determined. The length of the pre-delay line mPre can be adjusted based on the input pre-delay d. The input pre-delay is converted into samples and the length of the shortest delay line is subtracted therefrom. This can be set to the length mPre. This will cause the first pulse from the FDN to occur after time d. In some other embodiments, the diffusion portion of the FDN is set to start after time d. In this case, mPre. can be shorter and can be set based on an estimate of the time when the FDN output becomes diffuse and by setting the pre-delay line so that the desired time can be obtained.

[0229] In addition, as shown by 1409, based on the speaker setup and the directional gain, the output channel gain is determined. In these embodiments, the RT60 time may be different for different spatial directions. The output channel gain is adjusted based on the directional gain obtained from the analysis of the SRIR in the directional gain determiner. The speaker setup direction is compared to the direction associated with the directional gain. In a simple example, there is a one-to-one correspondence between the speaker setup direction and the direction used in the beamforming step of the directional gain determiner. In this case, the output channel gain c i can be set equal to the corresponding directional gain. If the directions are not the same, the output channel gain c can be set based on the closest directional gain i :

[0230] Furthermore, as indicated by 1411, reverberator parameters may be output.

[0231] about Fig.15 , showing a schematic diagram of an example binaural renderer 207 according to some embodiments.

[0232] The binaural renderer is configured to receive the directional reverberant audio signal 212s rev (t,i) and speaker settings 204θ ls (i) φ ls (i).

[0233] In some embodiments, the binaural renderer 207 includes HRTF processors 1501, 1511, 1521, which may be parallel or serial HRTF processors and which apply HRTF filters to h for speaker channels i based on the speaker setup 204. bin (m,i bin ,i) (where m is the time index of the filter coefficient and i bin are the indices of the binaural channels). In this example, Fig.15 There are 3 processors shown in , however, for N channels, there will be N processors, wherein the (channel) processor receives its corresponding channel directional reverberation audio signal and is configured to output a corresponding channel reverberation binaural signal.

[0234] Use HRTF filter to h bin (m,i bin ,i), the reverberant binaural audio signals 1502, 1512, 1522 can be determined for the channels of the directional reverberant audio signal by the following formula:

[0235]

[0236] in, represents a convolution (in some implementations, the filtering can also be performed in the frequency domain instead of performing a time domain convolution).

[0237] The reverberant binaural audio signals of channels 1502, 1512, 1532 may be passed to a binaural signal combiner 1503, which is configured to combine these signals to generate the reverberant binaural audio signal 214. In other words, the binaural signals for different speaker channels i are summed in the binaural signal combiner 1503 by the following formula:

[0238]

[0239] Thus, the reverberant binaural audio signal 214s is generated and outputted. bin (t,i bin ).

[0240] about Fig.16 , showing Fig.15 Flowchart of the operation of the example binaural renderer 207 shown in . Thus, for example, the following operations are shown:

[0241] As shown by 1601 , a speaker setup and a directional reverberant audio signal for a channel are obtained or otherwise received as input.

[0242] Then, as indicated by 1603 , after the speaker settings of the channels and the directional reverberant audio signals for the channels have been obtained, the HRTF based on the speaker settings may be applied to the channel directional reverberant audio signals.

[0243] Furthermore, as indicated by 1605 , the generated reverberant binaural audio signals are combined to generate a combined channel reverberant binaural audio signal.

[0244] Finally, as indicated by 1607 , the combined channel reverberation binaural audio signal is output.

[0245] In some embodiments, there may be multiple SRIRs captured from a room. In this case, as described above, analysis of directional attenuation and other reverberation parameters is performed for the SRIR. The analyzed parameters are associated with the corresponding position and orientation of the captured SRIR in the room. When the listener is rendered a reverberation signal in the room, interpolation is applied to the determined parameters to obtain reverberation parameters for the listening position and orientation. In a simple example, the parameters from the closest SRIR are used for the listener position. In other embodiments, interpolation between parameter values ​​from two or more SRIRs is used. One example includes triangulating the positions spanned by the positions of the SRIRs and determining a corresponding SRIR position triangle around the listener position for the listener position. In turn, the parameters from the triangular SRIR can be interpolated using appropriate weights, for example, by using a base amplitude translation (VBAP) gain for the triangular position. Any other suitable interpolation method can be used, for example, weighting the parameters of the SRIR by the distance from the listener to the SRIR, and calculating the weighted sum of the parameter values.

[0246] Similar to above, in the case of binaural rendering in six degrees of freedom (so that the listener can move in space and even have a single SRIR measured in the room), the directional gains can be interpolated from the closest directional gains for the direction from which a certain output channel of the reverberator is reproduced. This interpolation can be applied both when head tracking is applied to the reverberator output channel positions and when head tracking is not applied.

[0247] about Fig.17 , schematically illustrates an example system in which an embodiment is implemented in an encoder device 1901 that performs a portion of the functionality; writes data into a bitstream 1921 and sends the bitstream to a renderer device 1941, which decodes the bitstream, performs reverberator processing according to an embodiment, and outputs audio for headphone listening. Fig.17 For example, an apparatus suitable for performing spatial rendering operations is shown, in particular a renderer device 1941.

[0248] Fig.17 The encoder side 1901 of can be executed on the content creator computer and / or the network server computer. The output of the encoder is a bitstream 1921 that can be used for download or streaming. The decoder / renderer 1941 function runs on the end-user device, which can be a mobile device, personal computer, sound bar, tablet computer, car media system, home HiFi or theater system, head mounted display for AR or VR, smart watch, or any suitable system for audio consumption.

[0249] The encoder 1901 is configured to receive a virtual scene description 1900 and an audio signal 1904. The virtual scene description 1900 may be provided in the MPEG-I encoder input format (EIF) or in other suitable formats. Generally, the virtual scene description contains an acoustically relevant description of the content of the virtual scene, and for example contains scene geometry as a grid or voxels / voxels, acoustic materials, an acoustic environment with reverberation parameters, sound source locations, and other audio element related parameters, such as whether reverberation is to be rendered for the audio element.

[0250] In some embodiments, the encoder 1901 further comprises a scene encoder 1913 configured to obtain the virtual scene description 1900 and generate appropriate encoding scene parameters.

[0251] In the embodiments described herein, scene parameters are encoded into the bitstream payload.

[0252] The encoder 1901 further comprises an MPEG-H 3D audio encoder 1914 configured to obtain the audio signal 1904 , MPEG-H encode it and pass it to a bitstream encoder 1915 .

[0253] In some embodiments, encoder 1901 also includes a bitstream encoder 1915 configured to receive the output of scene encoder 1913 and the encoded audio signal from MPEG-H encoder 1914 and generate a bitstream 1921 that can be passed to a bitstream decoder 1941. In some embodiments, bitstream 1921 can be streamed to an end-user device or made available for download or storage.

[0254] In some embodiments, decoder 1941 includes a bitstream decoder 1951 configured to decode a bitstream.

[0255] The decoder 1941 may also include a scene decoder 1953 configured to obtain encoded scene parameters and decode them using an operation opposite or inverse to that of the scene encoder 1913 .

[0256] The room size and SRIR generator 1971 is configured to generate room size and SLIR and pass them to the reverberation parameter determiner 1953 and the directional gain determiner 1955. The reverberation parameter determiner 1953 and the directional gain determiner 1955 are the same as described above and are configured to pass their outputs to the reverberation controller 1955. The room size and SRIR generator 1971 may perform measurements or scans on the user equipment to obtain the room size and SLIR, or it may connect to a network server device to request such information for the current room.

[0257] In addition, the head posture generator 1957 receives information from a head mounted device or similar device and generates head posture information or parameters, which can be passed to the reverberator controller 1955, the binaural renderer 1962 and the direct sound binaural renderer 1963.

[0258] In some embodiments, the decoder 1941 includes a reverberator controller 1955 which also receives the output of the scene decoder 1953 and generates reverberation parameters for initializing the reverberator 1961 in the manner described above.

[0259] In some embodiments, the decoder 1941 includes an MPEG-H 3D audio decoder 1954 configured to decode the audio signal and pass it to a (FDN) reverberator 1961 and a direct sound processor 1965 .

[0260] The decoder 1941 also includes a (FDN) reverberator 1961 initialized by the reverberator controller 1955 and configured to achieve a fit-for-purpose reverberation of the audio signal.

[0261] The output of the (FDN) reverberator 1961 is configured to be output to a binaural signal combiner 1967 .

[0262] In addition, the decoder / renderer 1941 includes a direct sound processor 1965 which is configured to receive the decoded audio signal and is configured to implement any direct sound processing (such as air absorption and distance gain attenuation), and this can be passed to a direct sound binaural renderer 1963, which, using head orientation determination (from a suitable sensor), can generate a direct sound component which is passed to a binaural signal combiner 1967.

[0263] The binaural signal combiner 1967 is configured to combine the direct portion and the reverberant portion to generate a suitable output (eg, for headphone reproduction).

[0265] Although not shown, various other audio processing methods may be applied, such as early reflection rendering in combination with the proposed method.

[0266] Despite Fig.17The interface to the decoder / renderer 1941 is depicted as being the output from the room dimensions and SRIR generator 1971, but other interfaces are possible. In an alternative embodiment, one or both of the reverberation parameter determiner 1953 or the directional gain determiner 1955 may be located outside the decoder / renderer 1941. In this case, there may be an interface defined between the decoder / renderer 1941 via which the reverberation parameters and / or directional gain may be provided. An example is a listening-space-description interface, which may be a file or other suitable interface that may carry the room dimensions and SRIR (if the reverberation parameter determiner 1953 or the directional gain determiner 1955 is located inside the decoder / renderer 1941) or the room dimensions, reverberation parameters and directional gain (if the reverberation parameter determiner 1953 or the directional gain determiner 1955 is located outside the decoder or renderer 1941).

[0267] about Fig.18 , shows an example electronic device that can be used as any device part of the system described above. The device can be any suitable electronic device or device. For example, in some embodiments, the device 2000 is a mobile device, a user device, a tablet computer, a computer, an audio playback device, etc. The device can be configured to implement an encoder or a renderer or any functional block as described above.

[0268] In some embodiments, the device 2000 includes at least one processor or central processing unit 2007. The processor 2007 may be configured to execute various program codes, such as the methods described herein.

[0269] In some embodiments, the device 2000 includes a memory 2011. In some embodiments, at least one processor 2007 is coupled to the memory 2011. The memory 2011 can be any suitable storage component. In some embodiments, the memory 2011 includes a program code portion for storing program codes that can be implemented on the processor 2007. In addition, in some embodiments, the memory 2011 can also include a storage data portion for storing data (e.g., data that has been processed or will be processed according to the embodiments described herein). When needed, the implemented program code stored in the program code portion and the data stored in the storage data portion can be retrieved by the processor 2007 via the memory-processor coupling.

[0270] In some embodiments, the device 2000 includes a user interface 2005. In some embodiments, the user interface 2005 may be coupled to the processor 2007. In some embodiments, the processor 2007 may control the operation of the user interface 2005 and receive input from the user interface 2005. In some embodiments, the user interface 2005 may enable a user to enter commands to the device 2000, for example, via a keypad. In some embodiments, the user interface 2005 may enable a user to obtain information from the device 2000. For example, the user interface 2005 may include a display configured to display information from the device 2000 to the user. In some embodiments, the user interface 2005 may include a touch screen or touch interface that enables information to be input into the device 2000 and to display information to a user of the device 2000. In some embodiments, the user interface 2005 may be a user interface for communication.

[0271] In some embodiments, the device 2000 includes an input / output port 2009. In some embodiments, the input / output port 2009 includes a transceiver. In such embodiments, the transceiver can be coupled to the processor 2007 and configured to communicate with other devices or electronic devices, for example, via a wireless communication network. In some embodiments, the transceiver or any suitable transceiver or transmitter and / or receiver components can be configured to communicate with other electronic devices or devices via wired or wired coupling.

[0272] The transceiver can communicate with other devices via any suitable known communication protocol. For example, in some embodiments, the transceiver can use a suitable Universal Mobile Telecommunications System (UMTS) protocol, a wireless local area network (WLAN) protocol such as IEEE 802.X, a suitable short-range radio frequency communication protocol such as Bluetooth, or an infrared data communication path (IRDA).

[0273] Input / output port 2009 may be configured to receive signals.

[0274] In some embodiments, device 2000 may be used as at least part of a renderer.Input / output port 2009 may be coupled to a headset (which may be a head tracking or non-tracking headset) or the like.

[0275] In general, various embodiments of the present invention may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device, but the present invention is not limited thereto. Although various aspects of the present invention may be illustrated and described as block diagrams, flow charts, or using some other graphical representation, it is well known that the boxes, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware or controllers or other computing devices, or some combination thereof as non-limiting examples.

[0276] Embodiments of the present invention may be implemented by computer software executable by a data processor of a mobile device (such as in a processor entity), or by hardware, or by a combination of software and hardware. In addition, in this regard, it should be noted that any block of the logic flow as in the accompanying drawings may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on a physical medium such as a memory chip or a memory block implemented within a processor, on a magnetic medium such as a hard disk or a floppy disk, and on an optical medium such as a DVD and its data variants, a CD.

[0277] The memory may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The data processor may be of any type suitable for the local technical environment and may include, as non-limiting examples, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a gate level circuit based on a multi-core processor architecture, and a processor.

[0278] Embodiments of the present invention may be practiced in various components such as integrated circuit modules. The design of integrated circuits is generally a highly automated process. Complex and powerful software tools are available to convert a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0279] Programs, such as those offered by Synopsys, Inc. of Mountain View, Calif., and Cadence Design, of San Jose, Calif., use well-established design rules and a library of pre-stored design modules to automatically route conductors and position components on a semiconductor chip. Once the design of a semiconductor circuit is complete, the resulting design in a standardized electronic format (e.g., Opus, GDSII, etc.) can be transmitted to a semiconductor manufacturing facility or "fab" for fabrication.

[0280] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0281] (a) hardware circuit implementation only (such as analog and / or digital circuit implementation only); and

[0282] (b) a combination of hardware circuitry and software such as (where applicable):

[0283] (i) a combination of analog and / or digital hardware circuits and software / firmware; and

[0284] (ii) any portion of a hardware processor with software (including a digital signal processor, software and memory that work together to enable a device such as a mobile phone or server to perform various functions); and

[0285] A hardware circuit and / or processor, such as a microprocessor or portion of a microprocessor, that requires software (eg, firmware) to operate, but where the software may not be present for operation.

[0286] The above definition of "circuitry" applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term "circuitry" also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its accompanying software and / or firmware. The term "circuitry" also covers (for example and if applicable to the specific claimed element) a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0287] As used herein, the term "non-transitory" is a restriction on the medium itself (ie, tangible, as opposed to a signal), not on the persistence of data storage (eg, RAM versus ROM).

[0288] As used herein, “at least one of: <a list of two or more elements / elements>” and “at least one of <a list of two or more elements / elements>” and similar expressions (wherein a list of two or more elements / elements is connected by “and” or “or”) mean at least any one element / element, or at least any two or more elements / elements, or at least all elements / elements.

[0289] The foregoing description has provided a complete and useful description of exemplary embodiments of the present invention by way of exemplary and non-limiting examples. However, various modifications and adaptations will become apparent to those skilled in the relevant art in view of the above description when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of the present invention will still fall within the scope of the present invention as defined by the appended claims.

Claims

1. A method for generating a reverberant audio signal, the method comprising: obtaining at least one audio signal; obtaining at least one spatial room impulse response; determining at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configuring at least one reverberator based on the determined at least one parameter such that the at least one reverberator is configured to output audio in the at least one spatial direction; as well as At least one reverberant audio signal is generated based on the configured at least one reverberator and the at least one audio signal.

2. The method according to claim 1, wherein: Based on the at least one spatial room impulse response, determining at least one parameter includes: determining a common decay rate parameter, wherein, based on the determined at least one parameter, configuring the at least one reverberator includes: determining a common decay rate of at least one delay line decay filter for the at least one reverberator based on the common decay rate parameter and at least one dimension of at least one acoustic environment.

3. The method according to claim 2, wherein: Determining the common decay rate parameter includes determining the common decay rate parameter based at least in part on an omnidirectional component of the at least one spatial room impulse response.

4. The method according to claim 2 or 3, wherein: Determining the common decay rate parameter includes: determining an energy decay curve based on the omnidirectional component of the at least one spatial room impulse response; determining noise power based on the at least one spatial room impulse response; Determining a denoised energy decay curve based on the determined energy decay curve and the noise power; and The common decay rate parameter is determined according to the denoised energy decay curve.

5. The method according to claim 4, wherein: Based on the at least one spatial room impulse response, determining the at least one parameter comprises further determining at least one of the following: determining a pre-delay time based on the at least one spatial room impulse response; and An initial gain parameter is determined based on the denoised energy decay curve at the pre-delay time.

6. The method according to claim 5, wherein: Based on the at least one spatial room impulse response, determining the pre-delay time comprises: determining a diffuseness of the at least one spatial room impulse response; averaging the diffuseness over frequencies of the at least one spatial room impulse response; and A time at which the average value of the diffusion exceeds the determined threshold is determined, wherein the time is the pre-delay time.

7. The method according to any one of claims 5 or 6, wherein: Based on the at least one spatial room impulse response, determining the at least one parameter comprises: determining a direct sound peak within the at least one spatial room impulse response; applying windowing to the direct sound peaks to determine omnidirectional energy and energy of direct sound pulses of the at least one spatial room impulse response; and A reverberant to direct ratio is determined based on the omnidirectional energy and the energy of the direct sound impulse of the at least one spatial room impulse response.

8. The method according to any one of claims 1 to 7, wherein: Based on the determined at least one parameter, configuring the at least one reverberator comprises: determining, based on the at least one spatial room impulse response, at least one beamforming impulse response for a spatial direction associated with an output channel direction of the at least one reverberator; determining parameters for the at least one spatial direction based on the at least one beamforming impulse response; and Based on the at least one parameter, at least one output channel gain coefficient of the at least one reverberator is determined.

9. The method according to claim 8, wherein: Obtaining at least one spatial room impulse response includes obtaining a panoramic stereo surround sound impulse response measured in the at least one acoustic environment.

10. The method according to claim 9, wherein: Based on the at least one spatial room impulse response, determining at least one beamforming impulse response for a spatial direction associated with an output channel direction of the at least one reverberator comprises determining a beamforming impulse response based on applying spherical harmonics in at least one determined loudspeaker direction applied to the at least one spatial room impulse response.

11. The method according to any one of claims 8 to 10, wherein: Determining the at least one parameter for the at least one spatial direction based on the at least one beamforming impulse response comprises: determining an energy decay curve based on the at least one beamforming impulse response; determining noise power based on the at least one beamforming impulse response; Determining a denoised energy decay curve based on the determined energy decay curve and the noise power; and According to the denoised energy attenuation curve, a directional attenuation parameter is determined.

12. The method according to claim 11, wherein: Based on the at least one spatial room impulse response, determining at least one parameter comprises: obtaining another pre-delay time; and Based on the denoised energy decay curve at the another pre-delay time, another initial gain parameter is determined.

13. The method according to claim 12, wherein: Based on the at least one spatial room impulse response, determining at least one parameter comprises determining at least one directional gain based on the normalized further initial gain parameter.

14. A method according to any one of claims 12 or 13 as appended to any one of claims 5 or 6, wherein: The another pre-delay time is the pre-delay time.

15. The method according to any one of claims 1 to 14, wherein: The at least one audio signal is associated with at least one acoustic environment, and wherein the at least one spatial room impulse response is defined by the at least one acoustic environment.

16. The method according to claim 15, wherein: The at least one parameter comprises at least one directional attenuation parameter for at least one spatial direction within the at least one acoustic environment.

17. An apparatus comprising means for performing the method according to any one of claims 1 to 16.

18. A computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform the method according to any one of claims 1 to 16.

19. An apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: obtaining at least one audio signal; obtaining at least one spatial room impulse response; determining at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configuring at least one reverberator based on the determined at least one parameter such that the at least one reverberator is configured to output audio in the at least one spatial direction; as well as At least one reverberant audio signal is generated based on the configured at least one reverberator and the at least one audio signal.

20. An apparatus for generating a reverberant audio signal, comprising means for: obtaining at least one audio signal; obtaining at least one spatial room impulse response; determining at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configuring at least one reverberator based on the determined at least one parameter such that the at least one reverberator is configured to output audio in the at least one spatial direction; as well as At least one reverberant audio signal is generated based on the configured at least one reverberator and the at least one audio signal.

21. A computer-readable medium comprising instructions for causing an apparatus for generating a reverberant audio signal to at least perform the following operations: obtaining at least one audio signal; obtaining at least one spatial room impulse response; determining at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configuring at least one reverberator based on the determined at least one parameter such that the at least one reverberator is configured to output audio in the at least one spatial direction; as well as At least one reverberant audio signal is generated based on the configured at least one reverberator and the at least one audio signal.

22. An apparatus for generating a reverberant audio signal, the apparatus comprising: an acquisition circuit configured to obtain at least one audio signal; obtaining circuitry configured to obtain at least one spatial room impulse response; a determination circuit configured to determine at least one parameter based on the at least one spatial room impulse response, the at least one parameter being for at least one spatial direction; configuring circuitry configured to configure at least one reverberator based on the determined at least one parameter so that the at least one reverberator is configured to output audio in the at least one spatial direction; as well as The generating circuit is configured to generate at least one reverberant audio signal based on the configured at least one reverberator and the at least one audio signal.

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