Patent Description:
Sound bars comprising a plurality of transducers are well-established for different media applications, such as soundbars for television, smartphones and tablet computers. However, many of these conventional audio solutions are not perceived pleasant to the user. In particular, this is because many of these applications do not provide a comfortable 3D audio experience to the user.

<FIG> illustrates a conventional audio soundbar <NUM> having a linear array of transducers. Such audio devices may basically provide an improved 3D audio experiences to the user.

There is a need for an audio device and method providing an improved three-dimensional sound experience.

<CIT> provides an apparatus and a method for enhancing a spatial perception of an audio signal, creating increased interaural-level differences. To obtain this, two dipoles are used: one for producing a left audio signal and one for producing a right audio signal.

It is an object of the disclosure to provide an audio device as well as a corresponding method allowing for an improved three-dimensional sound experience.

According to a first aspect, the present disclosure relates to an audio device for generating a three-dimensional soundfield in accordance with appended claim <NUM>.

Thus, the audio device according to the first aspect allows to provide an improved three-dimensional sound experience by employing a first and a second dipole for crosstalk cancellation and a third dipole for sound elevation. Embodiments of the audio device have a toroidal housing and loudspeakers may be implemented in the housing. The soundfield may comprise a main radiation direction, which is based on the specific orientation of the loudspeakers mounted in the housing. Hereby, the main radiation direction may define an area proximate to which a listener may perceive a preferably high-quality 3D audio experience. The elliptical torus shape comprises as a specific case a circular torus shape. The elliptical, in particular circular arrangement of the loudspeakers within the toroidal housing may additionally define a compact geometry that may be useful for improved handling. Moreover, the elliptical, in particular circular arrangement of the loudspeakers enables to accommodate the loudspeakers in a manner, which enables to realize variable dipole distances in both horizontal and vertical directions. This allows to accurately adapt the frequency ranges of the soundfield according to the respective listener's needs by adapting the dipole distances of the horizontal and vertical dipoles accordingly. Additionally, using a plurality of horizontal dipoles and vertical dipoles having different dipole distances based on the elliptical, in particular circular arrangement enables the use of a preferably high total frequency bandwidth regarding both crosstalk cancellation portions and sound elevation portions. The loudspeakers can be coplanar or at least substantially coplanar and can be shared for horizontal and vertical dipole processing. Embodiments of the present disclosure also provide a portable and wearable audio device. Embodiments of the present disclosure also provide an accommodation area within the opening regime of the elliptical torus shape that may potentially be associated with a TV or another image or video device. According to some of these embodiments, the view direction of such a visual device may be adapted in accordance with the main radiation direction of the soundfield.

As used herein, "crosstalk cancellation" refers to an audio technique for delivering virtual 3D sound to a listener via two or more loudspeakers, wherein source signals are pre-processed prior to loudspeaker reproduction in order to ensure that first (e.g. left hand side) signal components of the loudspeakers may be prepared for and transmitted to a first ear (e.g. left ear) of the listener, and second (e.g. right hand side) signal components of the loudspeakers may be prepared for and transmitted to a second ear (e.g. right ear) of the listener different from the first ear. In doing so, virtually a substantial portion of acoustic crosstalk, in ideal circumstances all acoustic crosstalk, is cancelled out at the other ear and no significant reverberation is present. According to some embodiments, an angle Δγ defined by the propagation direction of dipoles formed for the first ear relative to the propagation direction of dipoles formed for the second ear may be in the range of <NUM>° ≤ Δγ ≤ <NUM>°.

In further (opposite) embodiments, the first signal components may be right hand side signal components and the first ear may be the right ear and the second signal components may be left hand side signal components and the second ear may be the left ear. For ease of understanding, the following description will describe embodiments, where the first signal components are the left hand side signal components and the first ear the left ear and the second signal components are the right hand side signal components and the second ear is the right ear, however all explanations correspondingly also apply to opposite embodiments.

As used herein, "sound elevation" refers to the perception of sound originating from sound sources, wherein the sound perception occurs at positions outside the 2D horizontal plane. Audio techniques for delivering such virtual 3D sound to a listener use, for instance, reflections by the ceiling of a room for simulating virtual source(s) located at a greater, i.e. "elevated" height than the original source(s). According to some embodiments, a propagation direction of a sound elevation portion of the soundfield may be adapted in accordance with dimensions of a type of location for which the machine is provided. According to some embodiments, angles Δβ<NUM> and Δβ<NUM>, respectively defined by a normal vector of a main plane defined by the elliptical torus shape of the housing and the propagation direction of the sound elevation portion of the soundfield may be in a range of <NUM>° ≤ Δβ<NUM> ≤ <NUM>° and <NUM>° ≤ Δβ<NUM> ≤ <NUM>°, wherein the propagation direction of the sound elevation portion of Δβ<NUM> may be directed upwards and the propagation direction of the sound elevation portion of Δβ<NUM> may be directed downwards. In certain embodiments, angles Δβ<NUM> and Δβ<NUM> may be in a range of <NUM>° ≤ Δβ<NUM> ≤ <NUM>° and <NUM>° ≤ Δβ<NUM> ≤ <NUM>°. In certain embodiments, angles Δβ<NUM> and Δβ<NUM> may be in a range of <NUM>° ≤ Δβ<NUM> ≤ <NUM>° and <NUM>° ≤ Δβ<NUM> ≤ <NUM>°. The specific ranges indicate herein enable a preferably good 3D sound experience to a listener having a preferably designated distance from the loudspeakers of the audio device. According to some embodiments, such preferably designated distance from the loudspeakers may be in a range extending from <NUM> to <NUM>.

The first frequency range may at least partially overlap the second frequency range. Alternatively, the first frequency range and the second frequency range may be non-overlapping. The second frequency range may extend to lower frequencies than the first frequency range. Further, a median frequency value of the second frequency range may be smaller than a median frequency value of the first frequency range.

The plurality of loudspeakers may be evenly distributed along the elliptical torus shaped housing. The first pair of loudspeakers forming the first dipole for crosstalk cancellation and the second pair of loudspeakers forming the second dipole for crosstalk cancellation may be arranged in the elliptical torus shaped housing such that the first dipole extends in a parallel or at least substantially parallel displaced orientation to the second dipole. The first pair of loudspeakers forming the first dipole for crosstalk cancellation and the third pair of loudspeakers forming the third dipole for sound elevation may be arranged in the elliptical torus shaped housing such that the first dipole extends in a perpendicular or at least substantially perpendicular orientation to the third dipole. The second pair of loudspeakers forming the second dipole for crosstalk cancellation and the third pair of loudspeakers forming the third dipole for sound elevation may be arranged in the elliptical torus shaped housing such that the second dipole extends in a perpendicular or at least substantially perpendicular orientation to the third dipole.

As used herein, "substantially horizontal", "substantially vertical", "substantially parallel", "substantially perpendicular" and similar expressions define a respective angular orientation with a deviation of less than <NUM>°, less than <NUM>°, less than <NUM>°, or less than <NUM>° from a strict horizontal, vertical, parallel or perpendicular angular orientation. According to some embodiments, these terminologies may be used to correlate geometrical and structural aspects of the audio device with each other in a relative manner. According to further embodiments, these terminologies may be used to correlate sound emission aspects of the audio device with each other in a relative manner. According to some embodiments, these terminologies may be used to correlate geometrical and structural aspects of the audio device with sound emission aspects of the audio device in a relative manner.

The elliptical torus shaped housing is configured to be arranged in an operation orientation such that a main plane defined by the housing, i.e. the plurality of loudspeakers mounted in the housing is a vertical or at least a substantially vertical plane. Hereby, the operation direction may be defined and aligned, respectively by a user, who intends to listen to the soundfield of the audio device. For instance, the housing of the audio device may be configured to be mounted to a wall or placed on a table such that in the operation orientation the plane defined by the housing is a vertical or at least substantially vertical plane. In the operation orientation of the audio device, the first pair of loudspeakers may form a first horizontal or at least substantially horizontal dipole for crosstalk cancellation, the second pair of loudspeakers may form a second horizontal or at least substantially horizontal dipole for crosstalk cancellation, which is located parallel or at least substantially parallel to the first horizontal or at least substantially horizontal dipole, but at a different vertical height than the first horizontal or at least substantially horizontal dipole, and the third pair of loudspeakers form a vertical or at least substantially vertical dipole for sound elevation of the soundfield, which is orientated perpendicular or at least substantially perpendicular to the first and/or second horizontal or at least substantially horizontal dipoles.

According to further implementations, the first frequency range (e.g. first audio frequency range) comprises a high frequency (HF) range and/or the second frequency range (e.g. second audio frequency range) comprises a mid frequency (MF) range. Advantageously, this allows providing crosstalk cancellation in the HF range by the first dipole having the smaller dipole distance. Further, this allows providing crosstalk cancellation in the MF range by the second dipole having the larger dipole distance. Thus, the crosstalk cancellation is achieved (at least more accurately) over a larger total frequency range. According to some implementations, the MF range may be within a range of <NUM><NUM> Hz ≤ MF ≤ <NUM><NUM> Hz and/or the HF range may be above <NUM><NUM> Hz. Such an acoustic dipole distance may be defined as the distance in between the positions of two acoustic transducers forming an acoustic dipole.

In a further possible implementation form of the first aspect, at least one loudspeaker of the first or second pair of loudspeakers is also part of the third pair of loudspeakers. Advantageously, this allows synergistically using one or more of the plurality of loudspeakers for more than one dipole and thereby enables a more compact housing as well as a less complex technical implementation.

In a further possible implementation form of the first aspect, the housing mounting the plurality of loudspeakers has a circular torus shape. Thus, the use of identical or at least similar dipole distances in a horizontal and vertical direction is enabled, which consequently enables to transmit identical or at least similar dipole frequencies regarding both crosstalk cancellation portions of the soundfield and sound elevation portions of the soundfield. This may be considered pleasant by a listener listening to the soundfield of the audio device and improve the overall audio quality. Additionally, similar dipole frequencies regarding both crosstalk cancellation portions of the soundfield and sound elevation portions of the soundfield may be even achieved in this case using at least partly the same loudspeakers regarding both vertical and horizontal dipole. In doing so, the number of loudspeakers required for providing crosstalk cancellation and for sound elevation may additionally be minimized.

In a further possible implementation form of the first aspect, an arrangement of the loudspeakers of the plurality of loudspeakers forming the first dipole defines a first dipole orientation and arrangement of the loudspeakers of the plurality of loudspeakers forming the third dipole defines a third dipole orientation, wherein a first dipole orientation angle η1 defined by the third dipole orientation relative to the first dipole orientation is in a range of <NUM>° ≤ η1 ≤ <NUM>°. Thereby, it is enabled to provide an improved three-dimensional sound experience by expanding well-established two-dimensional crosstalk cancellation technique by means of additional sound elevation portions providing an additional dimension of the soundfield, wherein the sound elevation portions are transmitted in specific angular directions, in which they minimally affect dipole fields relating to crosstalk cancellation. Consequently, three-dimensional sound experience may be achieved without significantly interfering with the well-established crosstalk cancellation technique.

As used herein, the "dipole orientation" may be defined as an arrangement of loudspeakers forming an acoustic dipole relative to each other. According to some embodiments, the dipole orientation refers to an arrangement of two loudspeakers relative to each other. According to some embodiments, the dipole orientation refers to the orientation of a connecting line in between two loudspeakers forming an acoustic dipole. According to some embodiments, this connecting line is not restricted to a specific direction and therefore includes both the connection in between a first loudspeaker and a second loudspeaker and vice versa.

As used herein, the "main radiation direction" of the 3D soundfield generated by the audio device may be defined as an area proximate to which a listener may perceive a preferably high-quality 3D audio experience. According to some embodiments, the main radiation direction may be the direction of the main power output of the soundfield generated by the audio device. According to some embodiments, the main radiation direction may be parallel or at least substantially parallel to the normal vector of the main plane defined by the elliptical torus shape of the housing. According to some further embodiments, the main radiation direction may in the operation position be perpendicular or at least substantially perpendicular to the main plane.

In a further possible implementation form of the first aspect, the processing circuitry is configured to process the plurality of input signals such that a fourth pair of the plurality of loudspeakers form a fourth dipole for crosstalk cancellation between left hand side signal components and right hand side signal components in the fourth frequency range of the soundfield, wherein a distance between the loudspeakers of the plurality of loudspeakers forming the fourth dipole is smaller than a distance between the loudspeakers of the plurality of loudspeakers forming the second dipole, i.e. the second dipole distance. Hereby, the fourth frequency range may extend to higher frequencies than the second frequency range and a distance between the loudspeakers of the plurality of loudspeakers forming the fourth dipole may be smaller than a distance between the loudspeakers of the plurality of loudspeakers forming the second dipole.

In doing so, the covered frequency range corresponding to the frequency portions of the crosstalk cancellation portions of the soundfield may be increased in certain cases. In particular, this may be the case if the fourth frequency range is not identical with the first frequency range (but may still have a certain overlapping regime).

Alternatively, the signal strength within at least a portion of the first frequency range or within a portion of the second frequency range may also be increased in certain cases. In particular, this may be the case if the first frequency range is at least partially identical with the fourth frequency range.

The distance between the loudspeakers of the plurality of loudspeakers forming the fourth dipole may be identical or at least substantially identical to the distance between the loudspeakers of the plurality of loudspeakers forming the first dipole, i.e. the first dipole distance. The fourth pair of loudspeakers forming the fourth dipole for crosstalk cancellation may be arranged in the elliptical torus shaped housing such that the fourth dipole extends in a parallel or at least substantially parallel displaced orientation to the first and/or second dipole and/or in a perpendicular or at least substantially perpendicular orientation to the third dipole. In the operation position of the audio device, the fourth pair of loudspeakers may form a fourth horizontal or at least substantially horizontal dipole for crosstalk cancellation, which is located parallel or at least substantially parallel to the first and second horizontal or at least substantially horizontal dipole, but at a different vertical height than the first and second horizontal or at least substantially horizontal dipole.

In a further possible implementation form of the first aspect, the processing circuitry is configured to process a first subset of the plurality of input signals to obtain the left hand side signal components, wherein for obtaining the output signals for the first pair of loudspeakers and the second pair of loudspeakers, the processing circuitry is configured to:.

As used herein, "bandpass filtering" refers to the signal processing technique of processing an input signal into one or more output signals, wherein the one or more output signals are identical or at least substantially identical to the input signal in one or more selected frequency ranges or bands, but otherwise zero or at least substantially zero. Bandpass filtering may be provided, for instance, using crossover filters providing one or more output signals. According to some implementations, such bandpass filtering means may enable to maintain several frequency ranges (e.g. high frequency range and mid frequency range) at the same time, while setting a remaining frequency range to zero or at least substantially zero. In doing so, a common bandpass filtering unit for maintaining both high frequency ranges and mid frequency ranges may be used.

As used herein, "equalizing" refers to the signal processing technique of equalizing an input signal using an equalization filter, wherein the left and right hand side signal components in the first and second frequency range are filtered to equalize, i.e. flatten the frequency response of the respective first and second dipole. According to some embodiments, first equalizing refers to equalizing input signals using a first equalization filter in a first frequency range. According to some embodiments, second equalizing refers to equalizing input signals using a second equalization filter in a second frequency range. According to some implementations, the first equalization filter and the second equalization filter may be different filters. According to some further implementations, the first equalization filter and the second equalization filter may be unique filters. According to some implementations, first equalizing and second equalizing may be performed by the same equalization filter.

In a further possible implementation form of the first aspect, the processing circuitry is further configured to process the first subset of the plurality of input signals to obtain the right hand side signal components, wherein for obtaining the output signals for the first pair of loudspeakers and the second pair of loudspeakers, the processing circuitry is further configured to:.

In a further possible implementation form of the first aspect, for obtaining channel signals, i.e. the left and right hand side signal components, the processing circuitry is further configured to apply a binauralizing based on a convolution of each input signal of the first subset of the plurality of input signals with a first binaural filter and a second binaural filter to obtain a first and a second binaurally filtered version of the respective input signal; and to apply downmixing to generate the left and right hand side signal components based on the first and second binaurally filtered version of each input signal.

Thereby, an improved 3D sound perception may be achieved using preferably simple technical means.

As used herein, "binauralizing" refers to the audio signal processing technique of applying a left ear head-related transfer function (HRTF) filter and a right ear head-related transfer function (HRTF) filter to an input signal. Such HRTF filter capture the transfer path characteristics of sound sources positioned in space and the human ears and may be used to create a virtual 3D sound perception.

According to some embodiments, binauralizing may also be applied within signal processing in order to obtain vertical dipole signals, which may then be used for sound elevation of the soundfield. According to some embodiments, downmixing may also be applied within signal processing in order to obtain vertical dipole signals, which may then be used for sound elevation of the soundfield.

In a further possible implementation form of the first aspect, the processing circuitry is configured to process the plurality of input signals such that the third pair of the plurality of loudspeakers form the third dipole for sound elevation in a third frequency range of the soundfield and a fifth pair of the plurality of loudspeakers form a fifth dipole for sound elevation in a fifth frequency range of the soundfield, wherein the third frequency range extends to higher frequencies than the fifth frequency range and a distance between the loudspeakers of the plurality of loudspeakers forming the third dipole, i.e. the third dipole distance, is smaller than a distance between the loudspeakers of the plurality of loudspeakers forming the fifth dipole, i.e. the fifth dipole distance. Advantageously, this allows for an even more efficient sound elevation in the third frequency range and the fifth frequency range of the soundfield.

The fifth pair of loudspeakers forming the fifth dipole for sound elevation may be arranged in the elliptical torus shaped housing such that the fifth dipole extends in a parallel or at least substantially parallel displaced orientation to the third dipole and/or in a perpendicular or at least substantially perpendicular orientation to the first and/or second dipole. In the operation position of the audio device, the fifth pair of loudspeakers may form a fifth vertical or at least substantially vertical dipole for sound elevation, which is located parallel or at least substantially parallel to the third vertical or at least substantially vertical dipole.

In a further possible implementation form of the first aspect, the third frequency range may correspond to the first frequency range and/or the fifth frequency range may correspond to the second frequency range. The third frequency range may comprise a high frequency (HF) range and/or the fifth frequency range may comprise a mid frequency (MF) range.

In a further possible implementation form of the first aspect, the plurality of input signals comprise vertical left hand side signal components, wherein for obtaining the output signals for the third pair of loudspeakers and the fifth pair of loudspeakers the processing circuitry is configured to:.

In a further possible implementation form of the first aspect, the processing circuitry is configured to process the plurality of input signals such that the second pair of the plurality of loudspeakers and a further pair of the plurality of loudspeakers form the second dipole, wherein a first loudspeaker of the further pair of loudspeakers is arranged in the housing adjacent to a first loudspeaker of the second pair of loudspeakers and a second loudspeaker of the further pair of loudspeakers is arranged in the housing adjacent to a second loudspeaker of the second pair of loudspeakers. Advantageously, this allows for a more efficient crosstalk cancellation in the second, e.g. MF frequency range.

In a further possible implementation form of the first aspect, the processing circuitry is configured to process the plurality of input signals such that the first loudspeaker of the second pair of loudspeakers and the first loudspeaker of the further pair of loudspeakers form a seventh dipole for sound elevation of the soundfield and/or the second loudspeaker of the second pair of loudspeakers and the second loudspeaker of the further pair of loudspeakers form an eighth dipole for sound elevation of the soundfield.

According to a second aspect, the present disclosure relates to a corresponding method for generating a three-dimensional soundfield using an audio device with a housing having an elliptical torus shape and a plurality of loudspeakers in accordance with appended claim <NUM>.

The second aspect comprises implementation forms which correspond to the implementation forms according to the first aspect.

In a further implementation according to the second aspect, the method may be configured to be executed by an audio device according to any of the embodiments disclosed herein.

According to a third aspect, the present disclosure relates to a computer program product in accordance with appended claim <NUM>.

In the following embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:.

In the following identical reference signs refer to identical or at least functionally equivalent features.

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and a plurality of preferred embodiments according to the present disclosure are defined in the appended claims.

For instance, it is to be understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa.

In the following, some theoretical background will be provided, which will be helpful for understanding specific aspects of exemplary embodiments of the audio device and method according to the present disclosure, before describing some exemplary embodiments of the audio device and method in greater detail.

According to well-established technical background, the simplest audio dipole source consist of two audio point sources (also referred to as "monopoles") of equal strength operating at the same frequency but vibrating <NUM> degrees out of phase with each other. In practice, an audio dipole can be obtained by driving two transducers, i.e. loudspeakers with the same signal, but with an inverted phase. Mathematically, an audio dipole can be expressed in the following way. If x(t) denotes the signal for driving the dipole, then y<NUM>(t) = x(t) can be the signal for driving the first monopole of the dipole and y<NUM>(t) = - x(t) can be the signal for driving the second monopole.

<FIG> illustrates a polar diagram indicating a directional dipole response at different frequencies. Ac can be deduced from <FIG>, the frequency response in the present example is more uniform for <NUM> than it is for <NUM>. <FIG> depicts a diagram indicating the frequency-dependent responses of dipoles having different dipole distances at a given point. As further can be deduced from <FIG>, the intensity of the acoustic dipole depends on both the frequency and the distance of the two monopoles. Generally, these relationships can be summarized as follows: (i) the smaller the distance between the monopoles, the higher the frequency where the directivity of the dipole starts beaming; and (ii) the closer the two monopoles, the higher the cancellation of the signal x(t) at low frequencies, where the interference is destructive. <FIG> hereby shows the response of two dipoles having a respective dipole distance of <NUM> and <NUM> at a given point. It is evident how the dipole having a dipole distance of <NUM> leads to a low frequency response roll-off.

Embodiments of the present disclosure make use of pairs of dipoles working at different frequencies, e.g. at lower and higher frequencies. Such a system can be referred to as a "<NUM> way" dipole system in that the audio frequency is split into two bands (lower and higher), which may be fed to two reproduction systems, i.e. the two dipoles. The crossover frequency, i.e. the frequency splitting the lower and the higher frequency band, can be obtained on the basis of the frequency response by looking for a compromise between beaming and low frequency cancellation (in <FIG> the crossover frequency could be set for example at <NUM>, where the response of the smaller dipole response rolls-off 6dB; the term "dipole distance" in <FIG> refers to the distance between the two loudspeakers forming the dipole).

Embodiments of the present disclosure make use of the fact that if a delay D is introduced in the signal feeding one of the two dipoles, i.e. y<NUM>(t) = -x(t-D), the directivity pattern of the dipole changes (as illustrated in the <NUM> degree depictions according to <FIG>). More specifically, a delay D may also cause following changes: (i) the lobe related to the delayed monopole is attenuated with respect to the other one (this implies there is less radiation in that direction); (ii) the zero of the dipole moves towards the delayed monopole; and (iii) the main lobe gets wider. According to some embodiment of the present disclosure, the delay D is in the range of <NUM> ≥ D ≥ <NUM>.

Embodiments of the present disclosure further make use of a dipole for reproducing binaural signals. Binaural signals are generally recorded (or synthesized using head-related transfer function filters) at the eardrums of a listener, and intended to provide accurate spatial sound when reproduced over headphones. If the two binaural signals are denoted as xL(t) and xR(t), a listener using a headphones may perceive xL(t) at his left ear, while he may perceive xR(t) at his right ear. In doing so, an accurate soundfield may be provided to the listener's eardrums, who has the impression to be present in the location where the recording took place.

Reproducing xL and xR with two loudspeakers (not headphones) worsens this experience, the main reason being the fact that xL and xR are now reaching both ears of the listener (which is not what was happening in the recording stage). The leakage of xL into the right ear and of xR into the left ear is called crosstalk, and is desirable to be avoided. In order to enhance binaural reproduction over loudspeakers, crosstalk cancellation may be implemented. Using dipoles is one possibility to implement crosstalk cancellation, which will be described in the following in greater detail in the context of <FIG> and <FIG>. A first dipole can be created using the following signals: <MAT> <MAT>.

This dipole provides having an intensity to be zero or to be at least substantially zero towards the right ear direction of the listener, so that crosstalk cancellation for the left binaural channel <NUM> may be achieved. Similarly, a second dipole can be created using the following signals: <MAT> <MAT>.

Such a dipole enables to transmit an intensity to be zero or to be at least substantially zero towards the left ear direction of the listener, so that crosstalk cancellation for the right binaural channel <NUM> may be achieved. Hereby, an angle Δγ defined by the left binaural channel <NUM> and the right binaural channel <NUM> may be adapted according to a real or designated distance of a listener <NUM> relative to the loudspeakers transmitting the dipole.

Embodiments of the present disclosure make use of the finding that reflections can be used for simulating virtual sources at an elevated height, i.e. for the purpose of "sound elevation", as e.g. described in <CIT>. According to the Haas principle, one requirement that may enable the user to perceive the sound reflection and not the direct sound coming from the source (i.e. the soundbar) is that the reflected sound reaching the user should be at least <NUM> dB louder than the direct sound. For this purpose, a vertical dipole can be generated and can be used to convey elevated sources content (as illustrated in <FIG>).

Depending on the geometry of the system, a delay D can be controlled in a specific manner in order to have an intensity to be zero or to be at least in the direction of the listener. Moreover, considering how the downward radiation would provide a reflected field coming from below the listener, the combination of upper and lower reflection would create confusing listening cues, and perception of elevated virtual sources would be blurred.

Applying an exemplary delay D of <NUM> microseconds on a dipole <NUM> spaced (i.e. the distance between the two loudspeakers forming the dipole is <NUM>), the pattern shown in <FIG> is achieved, where the upper lobe represents the pressure sent to the ceiling, the listener direction is the direct sound (which corresponds to the zero of the polar pattern), and the lower lobe is the attenuated pressure sent to the floor. The angular sector represents the vertical robustness of the system, where the direct sound is for example at least <NUM> dB less than the reflected one. Considering a specular reflection, the sound power reaching the listener after floor reflection is 6dB less than the one reaching the listener after the reflection at the ceiling.

<FIG> illustrates features of an audio device <NUM> for generating a three-dimensional soundfield according to an embodiment of the present disclosure. According to the embodiment depicted in <FIG>, the housing <NUM> having an elliptical torus shape is coplanar or at least substantially coplanar. In this case, one may define a main plane <NUM> spanned by the x axis and the y axis indicated in <FIG>, which is identical or at least parallel to the coplanar (or at least substantially coplanar) shape of the housing <NUM>, and which may be aligned such that a surface of the housing <NUM> is within the main plane <NUM>. In particular, the surface of the housing <NUM> facing to a listener of the soundfield may be within the main plane <NUM>. Hereby, an orientation of the main plane <NUM> may be characterized by a normal vector <NUM> oriented perpendicular to the main plane <NUM>. According to some embodiments, the normal vector <NUM> may be positioned such that the normal vector <NUM> extends along a symmetry axis of the torus-shaped housing <NUM>.

The audio device <NUM> comprises a housing <NUM> having an elliptical shape. According to some embodiments, the elliptical shape of the housing <NUM> may be a circular shape and a the length of a vertical elliptic axis 912a parallel to the z axis and a horizontal elliptic axis 912b parallel to the x axis are equal or at least substantially equal. Hereby, the vertical elliptic axis 912a and the horizontal elliptic axis 912b may be in a range of <NUM> ≤ 912a,912b ≤ <NUM>. According to some embodiments, the vertical elliptic axis 912a and the horizontal elliptic axis 912b may be in a range of <NUM> ≤ 912a,912b ≤ <NUM>. According to some further embodiments, the vertical elliptic axis 912a and the horizontal elliptic axis 912b may be in a range of <NUM> ≤ 912a,912b ≤ <NUM>. The opening regime <NUM> of the circular shape may be used for accommodating a media device, such as a television, smartphone or tablet computer. This means that a curvature in the upper and lower range of the housing <NUM> is identical or at least substantially identical to a curvature in the left and right range of the housing <NUM>. Such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive similar dipole distances regarding horizontal dipoles (DH1, DH2, DH3) and vertical dipoles (DV1, DV2, DV3). Therefore, such a geometry may be considered preferable in case that one may achieve similar frequency ranges and frequency range widths in both vertical and horizontal directions.

According to a further embodiment, the elliptical shape of the housing <NUM> comprises a vertical elliptic axis 912a parallel to the z axis and the vertical elliptic axis 912b parallel to the x axis, wherein the vertical elliptic axis 912a is greater than the horizontal elliptic axis 912b. This means that the curvature in the upper and lower range of the housing <NUM> is greater than the curvature in the left and right range of the housing <NUM>. Such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive smaller dipole distances regarding horizontal dipoles (DH1, DH2, DH3) compared to vertical dipoles (DV1, DV2, DV3). Accordingly, such a geometry may be considered preferable in case that one may achieve higher frequency ranges in the horizontal direction than in the vertical direction. Further, such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive a smaller variance in dipole distances in between horizontal dipoles (DH1, DH2, Dh3) compared to vertical dipoles (DV1, DV2, DV3). Accordingly, such a geometry may be considered preferable in case that one may achieve greater frequency range widths in the vertical direction than in the horizontal direction.

According to a further embodiment, the elliptical shape of the housing <NUM> comprises a vertical elliptic axis 912a parallel to the z axis and the horizontal elliptic axis 912b parallel to the x axis, wherein the vertical elliptic axis 912a is smaller than the horizontal elliptic axis 912b. This means that the curvature in the upper and lower range of the housing <NUM> is smaller than the curvature in the left and right range of the housing <NUM>. Such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive greater dipole distances regarding horizontal dipoles (DH1, DH2, DH3) compared to vertical dipoles (DV1, DV2, DV3). Accordingly, such a geometry may be considered preferable in case that one may achieve lower frequency ranges in the horizontal direction than in the vertical direction. Further, such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive a higher variance in dipole distances in between horizontal dipoles (DH1, DH2, DH3) compared to vertical dipoles (DV1, DV2, DV3).

The cross sections of the torus shaped housings may in general have any shape. The cross-sections may for example be (at least substantially) circular or elliptical cross sections, square, rectangular, hexagonal or octagonal cross sections.

According to <FIG>, the housing <NUM> may comprise openings in which the loudspeakers 901a-<NUM> may be accommodated. Such a configuration may achieve a preferably compact packaging of the audio device. However, according to further implementations, at least some of the loudspeakers 903a-<NUM> are mounted onto the coplanar surface of the housing <NUM> facing the listener of the soundfield. According to further implementations, at least some of the loudspeakers 903a-<NUM> are mounted outside along the periphery of the elliptical torus shape.

The audio device <NUM> may further comprise a processing circuitry <NUM> configured to process a plurality of input signals to obtain a plurality of output signals output to the plurality of loudspeakers. The processing circuitry <NUM> may, for example, be configured to process a plurality of input signals L, R, UL, UR to obtain a plurality of output signals LCH HF/<NUM>, RCH HF/<NUM>, LCH MF, RCH MF, UL HF, UR HF, UL MF, UR MF and output the plurality of output signals LCH HF/<NUM>, RCH HF/<NUM>, LCH MF, RCH MF, UL HF, UR HF, UL MF, UR MF to the plurality of loudspeakers 903a-<NUM>. In order to simplify visualization, however, the processing circuitry has not been depicted in <FIG>. According to some embodiments, the processing circuitry <NUM> of the audio device <NUM> may be based on any of the configurations depicted in <FIG>, <FIG> and <FIG>. The processing circuitry <NUM> of the audio device <NUM> may comprise hardware and/or software. The hardware may comprise digital circuitry, or both analogue and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors, e.g. software programmable processors. In one embodiment, the processing circuitry <NUM> comprises one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry executable program code which, when executed by the one or more processors, causes the audio device <NUM> to perform the operations or methods described herein.

<FIG> schematically depicts an audio device <NUM> according to an exemplary embodiment of the present disclosure implementing a plurality of horizontal dipoles DH1-DH3 for crosstalk cancellation and a plurality of vertical dipoles DV1-DV3 for sound elevation 1204a, 1204b. According to some embodiments, the processing circuitry <NUM> of the audio device <NUM> according to <FIG> (not depicted in <FIG>) may be based on any of the configurations depicted in <FIG>, <FIG> and <FIG>. According to some embodiments, the processing circuitry <NUM> of the audio device <NUM> may configured to process the plurality of input signals L, R, UL, UR (L represents input signals input by a left channel, R represents input signals input by a right channel signal, UL represents the vertical left hand side signal components and UR represents the vertical right hand side signal components) such that, for example, the loudspeakers 903b and <NUM>, represent a first pair of the plurality of loudspeakers 903a-<NUM>, which form a first dipole, namely a horizontal dipole (referred to as dipole horizontal <NUM> or short "DH1" in <FIG>) for crosstalk cancellation between left hand side signal components <NUM> and right hand side signal components <NUM> in a first frequency range of the soundfield (based on the principles described above in the context of <FIG>, <FIG> and <FIG>).

Moreover, the processing circuitry <NUM> of the audio device <NUM> may be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903c and <NUM> as a second pair of the plurality of loudspeakers 903a-<NUM> form a second dipole, namely a further horizontal dipole (referred to as dipole horizontal <NUM> or short "DH2" in <FIG>) for crosstalk cancellation between left hand side signal components <NUM> and right hand side signal components <NUM> in a second frequency range of the soundfield (based on the principles described above in the context of <FIG>, <FIG> and <FIG>). The first frequency range extends to higher frequencies than the second frequency range. In an embodiment, the first frequency range comprises a high frequency (HF) range and/or the second frequency range comprises a medium frequency (MF) range. According to some implementations, the MF range may be within a range of <NUM><NUM> Hz ≤ MF ≤ <NUM><NUM> Hz and/or the HF range may be above <NUM><NUM> Hz. According to some embodiments, the first frequency range and the second frequency range may have an overlapping range. According to further embodiments, the first frequency range and the second frequency range may be separate from each other, i.e. do not overlap.

As illustrated in <FIG>, by means of selecting a circular shape of the housing <NUM> and an equally or at least substantially equally space arrangement of the plurality of loudspeakers 903a-<NUM> within the housing <NUM>, the distance between the loudspeakers 903b and <NUM> forming the horizontal dipole DH1 may be smaller than the distance between the loudspeakers 903c and <NUM> forming the horizontal dipole DH2.

Moreover, the processing circuitry <NUM> of the audio device <NUM> may be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903f and <NUM> as a third pair of the plurality of loudspeakers 903a-<NUM> form a third dipole, namely a vertical dipole (referred to as dipole vertical <NUM> or short "DV1") for sound elevation 1204a, 1204b of the soundfield (based on the principles described above in the context of <FIG>). In this case, loudspeaker <NUM> may be used for two different acoustic dipoles, namely dipoles DH1 and DV1. Thereby, the number of required loudspeakers for achieving the three-dimensional soundfield may be reduced. Thereby, compactness of device packaging may be improved. Further, cost saving for the audio device production may be enabled.

According to a further embodiment, the processing circuitry <NUM> may also be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903b and 903d as a sixth pair of the plurality of loudspeakers 903a-<NUM> form a sixth dipole, namely a vertical dipole (referred to as dipole vertical <NUM> or short "DV3") for sound elevation 1204a, 1204b of the soundfield. In this case, loudspeaker 903b may be used for two different acoustic dipoles, namely dipoles DH1 and DV3. Thereby, the number of required loudspeakers for achieving the three-dimensional soundfield may be reduced. This may improve compactness of device packaging and may further enable cost saving for the audio device production.

According to a further embodiment, the processing circuitry <NUM> may also be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903a and 903e, i.e. a fifth pair of the plurality of loudspeakers 903a-<NUM> form a fifth dipole, namely a vertical dipole (referred to as dipole vertical <NUM> or short "DV2") for sound elevation 1204a, 1204b of the soundfield. In this case, none of the loudspeakers will be used for two different acoustic dipoles.

As further illustrated in the embodiment shown in <FIG>, the processing circuitry <NUM> of the audio device <NUM> may also be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903d and 903f, i.e. a fourth pair of the plurality of loudspeakers 903a-<NUM> form a fourth dipole (referred to as dipole horizontal <NUM> or short "DH3" in <FIG>) for crosstalk cancellation between left hand side signal components <NUM> and right hand side signal components <NUM> in the first frequency range or a different frequency range of the soundfield (based on the principles described above in the context of <FIG>, <FIG> and <FIG>). As illustrated in <FIG>, according to an embodiment, the first dipole DH1 and the fourth dipole DH3 may have the same dipole distance. In doing so, the intensity of the soundfield in the respective frequency range may be improved. In particular, this may be beneficial in case of having small loudspeakers, whose intensity is limited due to their small size. Another reason for doing so may be seen in that in this case, the power of the respective individual loudspeakers may be reduced, which may increase durability of each of the respective individual loudspeakers.

According to some embodiments, at least some or all of the dipole distances (DD) may be in the range of <NUM> ≤ DD ≤ <NUM>. According to some embodiments, at least one of the DD of the horizontal dipoles DH1-DH3 is equal or at least substantially equal with one of the DD of the vertical dipoles DV1-DV3. According to some embodiments, the DD of DH1, DH3, DV1 and DV3 may be equal or at least substantially equal. According to some embodiments, the DD of DH2 and DV2 may be equal or at least substantially equal.

As can be further deduced from <FIG> (which shows the same embodiment as <FIG> but additionally also dipole orientations and angles between different dipole orientations), the first dipole DH1 may have a first dipole orientation 907a, the second dipole DH2 may have a second dipole orientation 907b, the third dipole DV1 may have a third dipole orientation 907c, the fourth dipole DH3 may have a fourth dipole orientation 907d, the fifth dipole DV2 may have a fifth dipole orientation 907e and the sixth dipole DV3 may have a sixth dipole orientation 907f. Hereby, a first dipole orientation angle η1 may be defined by the first dipole orientation 907a relative to the third dipole orientation 907c, a second dipole orientation angle η2 may be defined by the sixth dipole orientation 907f relative to the first dipole orientation 907a, a third dipole orientation angle η3 may be defined by the fourth dipole orientation 907d relative to the sixth dipole orientation 907f, a fourth dipole orientation angle η4 may be defined by the third dipole orientation 907c relative to the fourth dipole orientation 907d, a fifth dipole orientation angle η4 may be defined by the third dipole orientation 907c relative to the second dipole orientation 907b, a sixth dipole orientation angle η6 may be defined by the third dipole orientation 907c relative to the second dipole orientation 907b, a seventh dipole orientation angle η7 may be defined by the sixth dipole orientation 907f relative to the second dipole orientation 907b and an eighth dipole orientation angle η8 may be defined by the third dipole orientation 907c relative to the second dipole orientation 907b.

According to some embodiments, at least one or several or even all of the dipole orientation angles η1-η8 may be in a range of <NUM>° ≤ηi≤ <NUM>°. According to some embodiments at least one or several or even all of the dipole orientation angles η1-η8 may be in a range of <NUM>° ≤ηi ≤ <NUM>°. According to some embodiments at least one or several or even all of the dipole orientation angles η1-η8 may be in a range of <NUM>° ≤ηi ≤ <NUM>°. According to some embodiments, the first, second and fourth dipole orientations 907a, 907b, 907d corresponding to dipoles DH1-DH3 are identical or at least substantially identical. According to some embodiments, the third, fifth and sixth dipole orientations 907c, 907e, 907f corresponding to dipoles DV1-DV3 are identical or at least substantially identical. According to some embodiments, first, second and fourth dipole orientations 907a, 907b, 907d corresponding to dipoles DH1-DH3 are perpendicular or at least substantially perpendicular to third, fifth and sixth dipole orientations 907c, 907e, 907f corresponding to dipoles DV1-DV3.

Additionally or alternatively to the horizontal dipoles DH1-D3 and the vertical dipoles DV1-DV3 depicted in <FIG>, the audio device <NUM> may comprise further substantially horizontal dipoles (not depicted in <FIG>). As an example, the loudspeakers <NUM> and 903a may form a further substantially horizontal dipole. The loudspeakers 903a and 903b may also form a further substantially horizontal dipole. The loudspeakers 903f and 903e may also form a further substantially horizontal dipole. The loudspeakers 903e and 903d may also form a further substantially horizontal dipole. As can be deduced from the configuration of <FIG>, these further substantially horizontal dipoles comprise dipole distances smaller than dipoles DH1-DH3 and DV1-DV3 from <FIG>, resulting in further dipole frequencies exceeding the first (HF) and second (MF) frequency ranges.

Additionally or alternatively, the audio device <NUM> may comprise further substantially vertical dipoles (not depicted in <FIG>). As an example, the loudspeakers <NUM> and <NUM> may form a further substantially vertical dipole. The loudspeakers <NUM> and 903f may form a further substantially vertical dipole. The loudspeakers 903b and 903c may form a further substantially vertical dipole. The loudspeakers 903c and 903d may form a further substantially vertical dipole. As can be deduced from the configuration of <FIG>, these further substantially vertical dipoles comprise dipole distances smaller than dipoles DH1-DH3 and DV1-DV3 from <FIG>, resulting in further dipole frequencies exceeding the first (HF) and second (MF) frequency ranges.

Additionally or alternatively, the audio device <NUM> may comprise further substantially vertical dipoles (not depicted in <FIG>). As an example, the loudspeakers 903a and 903f may form a further substantially vertical dipole. The loudspeakers 903a and 903d may form a further substantially vertical dipole. The loudspeakers <NUM> and 903e may form a further substantially vertical dipole. The loudspeakers 903b and 903e may form a further substantially vertical dipole. As can be deduced from the configuration of <FIG>, these further substantially vertical dipoles comprise dipole distances similar to dipoles DH2 and DV2 from <FIG>, resulting in further dipole frequencies similar to the second (MF) frequency range.

Alternatively to the configuration of <FIG>, the audio device <NUM> may also comprise a reduced number of loudspeakers 903a-<NUM> (not depicted). As an example, the device <NUM> may merely comprise loudspeakers 903b, 903c, <NUM> and <NUM>. In this case, the audio device comprises a first horizontal dipole DH1 based on loudspeakers 903b and <NUM> and a second horizontal dipole DH2 based on loudspeakers 903c and <NUM>. Additionally, this configuration comprises a first substantially vertical dipole DV1' based on loudspeakers <NUM> and <NUM> and a second substantially vertical dipole DV3' based on loudspeakers 903b and 903c. Such a configuration substantially enables to maintain the improved three-dimensional sound experience of the configuration of <FIG> and <FIG>, while at the same time achieves space-saving in the audio device <NUM> that may e.g. be used for accommodating further electronic components.

Moreover, as illustrated in the embodiment shown in <FIG>, the processing circuitry <NUM> of the audio device <NUM> may be further configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903a and 903e as a fifth pair of the plurality of loudspeakers 903a-<NUM> form a fifth dipole (referred to as dipole vertical <NUM> or short "DV2") for sound elevation 1204a, 1204b of the soundfield and such that the loudspeakers 903b and 903d as a sixth pair of the plurality of loudspeakers 903a-<NUM> form a sixth dipole (referred to as dipole vertical <NUM> or short "DV3") for sound elevation 1204a, 1204b of the soundfield (based on the principles described above in the context of <FIG>). As illustrated in <FIG>, according to an embodiment, the third dipole DV1 and the sixth dipole DV3 may have the same dipole distance. In doing so, the intensity of the soundfield in the respective frequency range may be improved.

Alternatively, the power of the respective individual loudspeakers may be reduced, which may increase durability of each of the respective individual loudspeakers. Hereby, the dipole distance of DV1 and DV3 may be smaller than the dipole distance of DV2.

As can be taken from the embodiment shown in <FIG>, the processing circuitry <NUM> of the audio device <NUM> may be configured to operate at least one of the plurality of loudspeakers 903a-<NUM> as a component of both a horizontal dipole and a vertical dipole. For instance, in the embodiment shown in <FIG>, the loudspeaker 903b is operated by the processing circuitry <NUM> of the audio device <NUM> as a component of both the first dipole DH1 and the sixth dipole DV3, the loudspeaker 903d is operated as a component of both the fourth dipole DH3 and the sixth dipole DV3, the loudspeaker 903f is operated as a component of both the fourth dipole DH3 and the third dipole DV1 and the loudspeaker <NUM> is operated as a component of both the first dipole DH1 and the third dipole DV1. Therefore, based on the configuration according to <FIG>, six dipole outputs (DH1, DH2, DH3, DV1, DV2, DV3) may be achieved based on merely eight loudspeakers 903a-<NUM>.

Although the embodiment shown in <FIG> comprises three horizontal dipoles DH1, DH2 and DH3 for crosstalk cancellation and three vertical dipoles DV1, DV2 and DV3 for sound elevation 1204a, 1204b, the person skilled in the art will appreciate that the audio device <NUM> can be implemented using more or less than the three horizontal and/or vertical dipoles shown in <FIG>.

In addition, although the embodiment shown in <FIG> comprises equally spaced loudspeakers 903a-<NUM>, one may deduce that non-equally spaced loudspeakers 903a-<NUM> may be provided according to other embodiments of the present disclosure. In particular, a non-equally spaced loudspeakers 903a-<NUM> may enable to have a soundfield having high intensity in a specific frequency range.

According to further embodiments, the audio device <NUM> may be configured to reproduce multichannel content which involves elevated sources similar to the multichannel audio format <NUM>. In an embodiment, the audio device <NUM> may be configured to handle the following channels-based input of the multichannel audio format <NUM>. <NUM> as follows: the horizontal input signals L, R, C, SL, SR, SBL, SBR (C represents an input signal input by a centered channel, SL represents an input signals input by the surround or front left channel, SR represents an input signal input by the surround or front right channel, SBL represents in input signal input by the surround back or rear left channel and SBR represents an input signal input by the surround back or rear right channel); and the vertical left and right hand signal components: UL, UR. According to some implementations, there may also be a reduced number of horizontal input signals. As an example, the horizontal input signals may also be restricted to L and R.

<FIG> illustrates an exemplary arrangement of the audio device <NUM> according to an exemplary embodiment of the disclosure within a room having a ceiling <NUM> and a floor <NUM> relative to a listener <NUM>. Hereby, the listener <NUM> may receive cross cancellation portions of the soundfield from at least the first dipole DH1 and the second dipole DH2. Further, the listener <NUM> may receive elevation portions 1204a, 1204b of the soundfield from at least the third dipole DV1. According to some embodiments, the listener <NUM> may receive cross cancellation portions of the soundfield from dipoles DH1-DH3. According to some further embodiments, the listener <NUM> may receive elevation portions 1204a, 1204b of the soundfield from dipoles DV1-DV3. Hereby, angles Δβ<NUM> and Δβ<NUM>, respectively defined by a normal vector <NUM> of a main plane defined by the elliptical torus shape of the housing and the propagation direction of the sound elevation portion of the soundfield may be in a range of <NUM>° ≤ Δβ<NUM> ≤ <NUM>° and <NUM>° ≤ Δβ<NUM> ≤ <NUM>°, wherein the propagation direction of the sound elevation portion of Δβ<NUM> may be directed upwards and the propagation direction of the sound elevation portion of Δβ<NUM> may be directed downwards. In certain embodiments, angles Δβ<NUM> and Δβ<NUM> may be in a range of <NUM>° ≤ Δβ<NUM> ≤ <NUM>° and <NUM>° ≤ Δβ<NUM> ≤ <NUM>°. In certain embodiments, angles Δβ<NUM> and Δβ<NUM> may be in a range of <NUM>° ≤ Δβ<NUM> ≤ <NUM>° and <NUM>° ≤ Δβ<NUM> ≤ <NUM>°. In certain embodiments, angles Δβ<NUM> and Δβ<NUM> may be in a range of <NUM>° ≤ Δβ<NUM> ≤ <NUM>° and <NUM>° ≤ Δβ<NUM> ≤ <NUM>°.

<FIG> and <FIG> schematically illustrate horizontal processing portions of a processing circuitry <NUM> of an audio device <NUM> according to an exemplary embodiment. According to <FIG>, processing of the plurality of horizontal input signals L, C, R, SL, SR, SBL, SBR and obtaining the output signals for the horizontal dipoles DH1, DH2 and DH3 is depicted. In the embodiment shown in <FIG> and <FIG>, the output signals for the horizontal dipoles DH1, DH2 and DH3 may be generated by the processing circuitry <NUM> of the audio device <NUM> on the basis of multichannel input signal according to the audio format <NUM>. <NUM>, namely the L, R, C, SL, SR, SBL, SBR input signals.

In a first processing stage, these horizontal signals may be "binauralized", i.e. convolved with binaural filters (Head Related Transfer Functions) in order to obtain binaural signals corresponding to the horizontal loudspeakers 903a-<NUM> in the <NUM>. <NUM> setup (see "binauralization" block <NUM> in <FIG>). Afterwards, the seven stereo signals may be summed together to form a stereo downmix (see "downmixing" block <NUM> in <FIG>). Thereafter, the resulting first or left channel signal LCH and second or right channel signal RCH can be "bandpass"-filtered using a crossover block <NUM>, for instance, low-pass, band-pass and high-pass filtered in order to obtain for each of both a horizontal three way stereo signal (LH, MH, HH; where "LF" stands for Low Frequency, "MF" stands for Mid-Frequency, "HF" stands for High-Frequency). According to an embodiment, the low passed version LH may be obtained using a low pass filter with a cutoff frequency fL, the band pass filter may provide a bandpassed version MH between the frequencies fL and fM, while the high frequency part or portion HF may be obtained using a high-pass filter with a cutoff frequency fH. According to an embodiment, these different frequencies associated with the downmixing block <NUM> may be determined on the basis of the specific configuration of the audio device <NUM> and its use case. For instance, a suitable lower cutoff frequency fL can be determined on the basis of the electroacoustic properties of the audio device <NUM>, such as the type of loudspeakers 903a-<NUM>, amplifiers and the like. A suitable frequency fM can be obtained by analysing the frequency response of the first and second horizontal dipoles DH1 and DH2 and by determining a compromise between beaming and low frequency cancellation (as already described above in the context of <FIG>). For example, in an embodiment with the housing <NUM> of the audio device <NUM> having a diameter of <NUM>, a dipole distance of the first and third horizontal dipole DH1, DH3 of <NUM> and a dipole distance of the second horizontal dipole DH2 of <NUM> the frequency fM can be about <NUM>.

As can be taken from <FIG>, the horizontal MF and HFsignals may be fed to a <NUM>-way dipole based crosstalk cancellation network including a crossover unit <NUM> and reproduced by the audio device <NUM>. The horizontal HF may be equally splitted to the processing block <NUM> for the first and third horizontal dipole DH1 and DH3, while the horizontal MF may be reproduced by the processing block <NUM> for the second horizontal dipole DH2. The delay D may be adapted in order to achieve optimal crosstalk cancellation at the listener position, namely to steer the zeros of the Left and Right Dipole to the corresponding contralateral ear (as illustrated in <FIG> and <FIG>). For example, if it is assumed that a "sweet spot" listener position is around <NUM> meters away in front of the audio device <NUM> (as illustrated in <FIG>), the delay D can be adjusted until the correct position of the zeros is achieved, for instance, a delay D of <NUM> microseconds.

According to the embodiment illustrated in <FIG>, the horizontal LF horizontal signals can be summed with the vertical LF components of the vertical signals (described in more detail in the context of <FIG> and <FIG>), and may be directly routed to the loudspeakers 903b, 903d, 903f, <NUM>, namely: horizontal and vertical LF from the first or left channel to the loudspeakers 903f and <NUM>, and horizontal and vertical LF from the right or second channel to the loudspeakers 903b and 903d. In this embodiment, the loudspeakers 903b, 903c, 903d and <NUM> may correspond to horizontal HF dipole components only and may therefore be less prone to over excursion.

The effect of the full processing chain for the horizontal components implemented by the processing circuitry <NUM> of the audio device <NUM> according to an embodiment and shown in <FIG> may be that the listener sitting in front of the audio device <NUM> has the impression of being surrounded by the <NUM> horizontal speakers as defined by the <NUM>. <NUM> audio format.

A portion <NUM> of the full processing chain for the horizontal components is illustrated in more detail in <FIG>. As can be taken from <FIG>, the processing circuitry <NUM> of the audio device <NUM> may be configured to apply a bandpass filtering to the left hand side signal components LCH provided by the downmix unit <NUM>. Hereby, the crossover unit 1305a is used to obtain left hand side signal components LCH HF/<NUM> in the first frequency range HF and left hand side signal components LCH MF in the second frequency range MF. Optionally, the crossover unit 1305a may be also used to obtain left hand side signal components LCH LF in a first frequency range LF. Moreover, the processing circuitry <NUM> of the audio device <NUM> may be configured to implement a first dipole processing unit 1307a for generating components of the output signals for feeding the loudspeakers 903b, 903d, 903f, <NUM> of the first and fourth dipole DH1 and DH3 and to implement a second dipole processing unit 1309a for generating components of the output signals for feeding the loudspeakers 903c, <NUM> of the second dipole DH2.

Moreover, the processing circuitry <NUM> of the audio device <NUM> may be configured to apply a bandpass filtering to the right hand side signal components RCH provided by the downmix unit <NUM>. Hereby, the crossover unit 1305b is used to obtain right hand side signal components RCH HF/<NUM> in the first frequency range HF and right hand side signal components RCH MF in the second frequency range MF. Optionally, the crossover unit 1305a may be also used to obtain right hand side signal components RCH LF in a first frequency range LF. Moreover, the processing circuitry <NUM> of the audio device <NUM> may be configured to implement a third dipole processing unit 1307b for generating further components of the output signals for feeding the loudspeakers 903b, 903d, 903f, <NUM> of the first and fourth dipole DH1 and DH3 and to implement a fourth dipole processing unit 1309b for generating further components of the output signals for feeding the loudspeakers 903c, <NUM> of the second horizontal dipole DH2.

A possible implementation of the first dipole processing unit 1307a for generating components of the output signals for feeding the loudspeakers 903b, 903d, 903f, <NUM> of the first and fourth dipole DH1 and DH3 is shown in <FIG>. As can be deduced from <FIG>, the left hand side signal components LCH HF/<NUM> input to the first dipole processing unit 1307a may be provided to an equalization filter <NUM>. In a similar manner, the left hand side signal components LCH MF may be input to the second dipole processing unit 1309a.

According to a first processing branch 1404a of the first dipole processing unit 1307a shown in <FIG> the intermediate signal provided by the equalization filter <NUM> may be provided as an output signal at a plus-phased (+) output of the first dipole processing unit 1307a, for instance, to the loudspeaker <NUM> (e.g. for LCH HF/<NUM>). According to the second processing branch 1404b of the first dipole processing unit 1307a shown in <FIG> the intermediate signal provided by the equalization filter <NUM> may be provided to an inverter unit <NUM>, to a delay unit <NUM> and then as an output signal at a minus-phased (-) output of the first dipole processing unit 1307a, for instance, to the loudspeaker 903b (e.g. for LCH HF/<NUM>). As will be appreciated, the order of the inversion <NUM> and the delay <NUM> in the second processing chain of the first dipole processing unit 1307a could be changed. As already described in the context of <FIG> above, by means of the delay added by the delay unit <NUM> it may be possible to control and steer the direction of the null of the corresponding dipole. <FIG> shows the corresponding directional dipole response. The null of the dipole is steered by the angle α. The second dipole processing unit 1309a, the third dipole processing unit 1307b and the fourth dipole processing unit 1309b shown in <FIG> may be implemented in the same way as the first dipole processing unit 1307a, as shown in <FIG> and described above.

According to some further implementations, the first dipole processing unit 1307a may also comprise the equalization filter <NUM>, the inverter unit <NUM> and the delay unit <NUM>, however, the ordering of these elements may be modified. The same also applies to further implementations of the second dipole processing unit 1309a, the third dipole processing unit 1307b and the fourth dipole processing unit 1309b.

According to some further implementations, the first processing branch 1404a and the second processing branch 1404b of the first dipole processing unit 1307a may be interchanged with each other. In this case, the corresponding directional dipole response is different from <FIG> and may correspond to a mirroring transformation of the dipole response according to <FIG> along the y axis.

<FIG> represents a dipole response indicating the effect of equalization effected by the first dipole processing unit 1307a according to some embodiments. <FIG> depicts the effect of bandpass filtering provided by a crossover unit 1305a of the audio device <NUM> according to an exemplary embodiment. <FIG> depicts the directional response illustrating the "flattening" effect of the equalization filter <NUM> of the first dipole processing unit 1307a according to some embodiments, while <FIG> illustrates exemplary HF, MF and LF frequency bands (with fL at <NUM> and fH at <NUM>) implemented by the crossover unit 1305a shown in <FIG>. As already described, the suitable transition frequencies primarily depend on the distance between the loudspeakers 903a-<NUM> defining the dipoles and the configuration of the vertical and horizontal dipoles. Optimally, the larger the distance between the loudspeakers 903a-<NUM>, the lower the frequencies reproduced by that pair of loudspeakers 903a-<NUM>.

As can be deduced from <FIG> again, the processing circuitry <NUM> of the audio device <NUM> is configured to generate, for instance, the output signals for driving the loudspeakers 903b and <NUM> of the first dipole DH1 in the following way. A first component (e.g. left channel component) of the output signal for the loudspeaker 903b is provided as the output signal at the minus-phased (-) output of the first dipole processing unit 1307a, which is based on the left hand side signal component LCH HF/<NUM> in the first frequency range HF. A second component (e.g. right channel component) of the output signal for the loudspeaker 903b is provided as the output signal at the plus-phased (+) output of the third dipole processing unit 1307b, which is based on the right hand side signal component RCH HF/<NUM> in the first frequency range HF. Likewise, a first (e.g. left channel) component of the output signal for the loudspeaker <NUM> is provided as the output signal at the plus-phased (+) output of the first dipole processing unit 1307a, which is based on the left hand side signal component LCH HF/<NUM> in the first frequency range HF. A second (e.g. right channel) component of the output signal for the loudspeaker <NUM> is provided as the output signal at the minus-phased (-) output of the third dipole processing unit 1307b, which is based on the right hand side signal component RCH HF/<NUM> in the first frequency range. As can be taken from <FIG>, the same processing can be used for generating the first (e.g. left channel) and second (e.g. right channel) components of the output signals for the loudspeakers 903d and 903f of the fourth horizontal dipole DH3.

As can be taken from <FIG>, the processing circuitry <NUM> of the audio device <NUM> is configured to generate the output signals for driving the loudspeakers 903c and <NUM> of the second dipole DH2 (having a larger dipole distance than the first and fourth dipole DH1 and DH3) in the following way. A first (e.g. left channel) component of the output signal for the loudspeaker 903c is provided as the output signal at the minus-phased (-) output of the second dipole processing unit 1309a, which is based on the left hand side signal component LCH MF in the second frequency range. A second (e.g. right channel) component of the output signal for the loudspeaker 903c is provided as the output signal at the plus-phased (+) output of the fourth dipole processing unit 1309b, which is based on the right hand side signal component RCH MF in the second frequency range MF. Likewise, a first (e.g. left channel) component of the output signal for the loudspeaker <NUM> is provided as the output signal at the plus-phased (+) output of the second dipole processing unit 1309a, which is based on the left hand side signal component LCH MF in the second frequency. A second (e.g. right channel) component of the output signal for the loudspeaker <NUM> is provided as the output signal at the minus-phased (-) output of the fourth dipole processing unit 1309b, which is based on the right hand side signal component RCH MF in the second frequency range MF.

The LF band limited right channel or left channel signals can be directly output to a subset of the plurality of loudspeakers 903a-<NUM>, such as the loudspeakers 903f and <NUM> and/or 903b and 903d, or even to all loudspeakers 903a-<NUM>.

<FIG>, <FIG> schematically illustrate vertical processing portions of the processing circuitry <NUM> of an audio device according to an exemplary embodiment. Hereby, processing the plurality of vertical left and right hand side components UL, UR and obtaining the output signals for the vertical dipoles DV1, DV2 and DV3 is depicted. According to some embodiments, these vertical left and right hand side components UL, UR may also be indicated as elevated hand side components UL, UR. In the embodiment shown in <FIG> and <FIG>, the output signals for the vertical dipoles DV1, DV2 and DV3 are generated by the processing circuitry <NUM> of the audio device <NUM> on the basis of the vertical channels of a multichannel input signal according to the audio format <NUM>. <NUM>, namely the vertical left and right hand side components UL and UR.

As can be taken from <FIG>, according to an embodiment the processing circuitry <NUM> of the audio device <NUM> is configured to apply a low-pass (LF), band-pass (MF) and high-pass (HF) filtering to the vertical left and right hand side components UL and UR signal using a crossover unit <NUM> in order to obtain a vertical three way stereo signal (UL HF, UR HF; UL MF, UR MF; UL LF, UR LF). Similar considerations as for the horizontal components hold (e.g. for setting the transition frequencies of the filters employed by the crossover unit <NUM>). According to an embodiment, the sum of vertical UL MF and UR MF is fed to the fifth dipole DV2 (i.e. the central vertical dipole), while the UL HF is fed to the third dipole DV1 (i.e. the left hand side vertical dipole) and the UR HF is fed to the sixth dipole DV3 (i.e. the right hand side vertical dipole). The LF band limited signals, i.e. UL LF and UR LF, can be directly output to a subset of the plurality of loudspeakers 903a-<NUM>, such as the loudspeakers 903f and <NUM> and/or 903b and 903d, or even to all loudspeakers 903a-<NUM>. Hereby, LF band limited signals may be emitted commonly using monopole transducers.

<FIG> provides additional specifications regarding generating the output signals for the vertical dipoles DV1, DV2 and DV3 according to an embodiment, which is similar to the processing for the horizontal dipoles DH1-DH3 depicted in <FIG> in that for providing the output signals for the vertical dipoles, dipole processing units 1503a, 1505a, 1503b, 1505b are used, which can be similar to or identical to the first dipole processing unit 1307a shown in <FIG> and described above.

According to an embodiment, the processing circuitry <NUM> of the audio device <NUM> is configured to generate the output signals for driving the loudspeakers 903a and 903e of the fifth dipole DV2 (having a larger dipole distance than the third and sixth dipole DV1 and DV3) in the following way. A first, e.g. elevated, component of the output signal for the loudspeaker 903a is provided as the output signal at the plus-phased (+) output of the dipole processing unit 1505a, which is based on the vertical left hand side signal component UL MF in the second frequency range MF. A second, e.g. deepened, component of the output signal for the loudspeaker 903a is provided as the output signal at the minus-phased (-) output of the dipole processing unit 1505b, which is based on the vertical right hand side signal component UR MF in the second frequency range MF. Likewise, a first component of the output signal for the loudspeaker 903e is provided as the output signal at the minus-phased (-) output of the dipole processing unit 1505a, which is based on the vertical left hand side signal component UL MF in the second frequency range MF. The second component of the output signal for the loudspeaker 903e is provided as the output signal at the plus-phased (+) output of the dipole processing unit 1505b, which is based on the vertical right hand side signal component UR MF in the second frequency range MF.

As further illustrated in <FIG>, the output signal for the loudspeaker <NUM> of the third dipole DV1 can be provided as the output signal at the plus-phased (+) output of the dipole processing unit 1503a, which is based on the vertical left hand side signal component UL HF in the first frequency range HF, while the output signal for the loudspeaker 903f of the third dipole DV1 can be provided as the output signal at the minus-phased (-) output of the dipole processing unit 1503a. Likewise, the output signal for the loudspeaker 903d of the sixth dipole DV3 can be provided as the output signal at the minus-phased (-) output of the dipole processing unit 1503b, which is based on the vertical right hand side signal component UR HF in the first frequency range HF while the output signal for the loudspeaker 903b of the sixth dipole DV3 can be provided as the output signal at the plus-phased (+) output of the dipole processing unit 1503b.

As in the case of the horizontal dipoles, the LF band limited signals, i.e. UL LF and UR LF, can be directly output to a subset of the plurality of loudspeakers 903a-<NUM>, such as the loudspeakers 903f and <NUM> and/or 903b and 903d, or even to all loudspeakers 903a-<NUM>.

<FIG> schematically depicts an audio device <NUM> according to a further exemplary embodiment of the present disclosure implementing a plurality of horizontal dipoles DH1-DH3 for crosstalk cancellation and a plurality of vertical dipoles DV1-DV3 for sound elevation 1204a, 1204b. The embodiment of the audio device <NUM> shown in <FIG> differs from the audio device <NUM> shown in <FIG> in that in the embodiment of <FIG>, the second dipole DH2 and/or the fifth dipole DV2 are formed by four "identical" loudspeakers, namely the second dipole DH2 by the loudspeakers 903c, 903c' and <NUM>, <NUM>' and the fifth dipole DV2 by the loudspeakers 903a, 903a' and 903e, 903e'. This allows to increase intensity of the frequency ranges transmitted by the second dipole DH2 and/or the fifth dipole DV2. According to some embodiments, the second frequency range of the second dipole DH2 and/or the fifth frequency range of the fifth dipole DV may correspond to a MF range. In this case, MF frequency range intensities of the soundfield may be increased. According to some embodiments, this may be because a single loudspeaker may quickly reach its maximum excursion so that distortion may occur. Thus, using at least two loudspeakers to implement a respective monopole allows for providing more headroom to the loudspeakers as well as reducing fM, thereby pushing the frequency bands in which the spatial rendering is effective to specific frequencies.

<FIG> schematically depicts an audio device <NUM> according to a further exemplary embodiment of the present disclosure implementing a plurality of horizontal dipoles DH1-DH3 for crosstalk cancellation and a plurality of vertical dipoles DV1-DV3 for sound elevation 1204a-1204b. Hereby, <FIG> refers to a modification of the embodiment according to <FIG>. In the embodiment shown in <FIG>, the processing circuitry <NUM> of the audio device <NUM> is configured to process the plurality of input signals L, R, UL, UR such that the loudspeaker 903c and the immediately adjacent loudspeaker 903c' form an seventh dipole DV5 for sound elevation 1204a, 1204b of the soundfield and/or the loudspeaker <NUM> and the immediately adjacent loudspeaker <NUM>' form an eighth dipole DV4 for sound elevation 1204a, 1204b of the soundfield. As can be taken from <FIG>, the dipole distances of the vertical dipoles DV4 and/or DV5 are even smaller than the dipole distances of the dipoles DV1, DV2 and DV3. For generating the output signals for the loudspeakers of the dipoles DV4 and/or DV5, the same approach as for the embodiment shown in <FIG>, <FIG>, <FIG> can be used. More specifically, the Vertical High Frequencies (HighF-V) can still be split into two parts, namely Mid-HighF-V and VeryHighF-V, introducing a cutoff frequency fH that can be set considering the beaming frequency (also called aliasing frequency) of the Mid-High Dipoles, i.e. the third and sixth dipole DV1 and DV3.

<FIG> is a schematic diagram illustrating a portion of the processing circuitry <NUM> of the audio device <NUM> according to a further embodiment. In the embodiment shown in <FIG>, the audio device <NUM> is configured to reproduce a stereo input signal by further comprising an upmixing stage <NUM> that is configured to extract the ambience components of the stereo input signal. For further details concerning a possible implementation of the upmixing stage <NUM>, reference is made to <NPL>. As illustrated in <FIG>, the upmixing stage <NUM> has a stereo input (L and R) and can output a <NUM> output signal, i.e. L, R, C, SR, SL, LFE. According to an embodiment, the reproduction strategy for L, R, C and LFE is identical to the one for the <NUM>. <NUM> case illustrated in <FIG>, <FIG> and <FIG>, <FIG>. In order to force content for the elevated channels, the ambience channels SR and SL can be each split in <NUM> components: for example the SR channel and the SL channel can be attenuated by <NUM> dB using respective attenuation stages 1803a, b and duplicated to form a Horizontal SR and SL, H-SR and H-SL, signal and a Vertical SR and SL, V-SR and V-SL, signal. The rest of the processing is identical or at least similar to the processing already described in the context of <FIG>, <FIG> and <FIG>, <FIG>.

In a modification of the embodiment shown in <FIG>, the plurality of input signals L, R, UL, UR can be the signals according to the <NUM> audio format. In this case there is no need for the upmixing stage <NUM>, and the vertical component can be obtained as in the previous embodiment from the SR and SL ambience channels.

<FIG> is a flow diagram illustrating a method <NUM> for generating a three-dimensional soundfield according to an embodiment of the present disclosure. The method <NUM> comprises the step <NUM> of processing a plurality of input signals L, R, UL, UR to obtain a plurality of output signals and the step <NUM> of outputting the plurality of output signals LCH HF/<NUM>, RCH HF/<NUM>, LCH MF, RCH MF, UL HF, UR HF, UL MF, UR MF to the plurality of loudspeakers 903a-<NUM>. According to the method <NUM>, the plurality of input signals are processed such that:.

The person skilled in the art will understand that the "blocks" ("units") of the various figures (method and apparatus) represent or describe functionalities of embodiments of the present disclosure (rather than necessarily individual "units" in hardware or software) and thus describe equally functions or features of apparatus embodiments as well as method embodiments (unit = step).

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described apparatus embodiment is merely exemplary.

Claim 1:
An audio device (<NUM>) for generating a three-dimensional soundfield, wherein the audio device (<NUM>) comprises:
- a housing (<NUM>), in use configured to be arranged in an operation orientation having a vertical or substantially vertical main plane (<NUM>), the housing having an elliptical torus shape and a plurality of loudspeakers (903a-<NUM>); and
- a processing circuitry (<NUM>) configured to process a plurality of input signals (L, R, UL, UR), to obtain a plurality of output signals (LCH HF/<NUM>, RCH HF/<NUM>, LCH MF, RCH MF, UL HF, UR HF, UL MF, UR MF) and output the plurality of output signals (LCH HF/<NUM>, RCH HF/<NUM>, LCH MF, RCH MF, UL HF, UR HF, UL MF, UR MF) to the plurality of loudspeakers (903a-<NUM>), wherein the processing circuitry (<NUM>) is configured to process the plurality of input signals (L, R, UL, UR) such that:
- a first pair (903b, <NUM>; 903d, 903f) of the plurality of loudspeakers (903a-<NUM>) form a first dipole (DH1, DH3) for crosstalk cancellation between left hand side signal components (LCH HF/<NUM>) and right hand side signal components (RCH HF/<NUM>) in a first frequency range (HF) of the soundfield;
- a second pair (903c, <NUM>) of the plurality of loudspeakers (903a-<NUM>) form a second dipole (DH2) for crosstalk cancellation between left hand side signal components (LCH MF) and right hand side signal components (RCH MF) in a second frequency range (MF) of the soundfield; and
- a third pair (903f, <NUM>; 903b, 903d) of the plurality of loudspeakers (903a-<NUM>) form a third dipole (DV1, DV3) for sound elevation (1204a, 1204b) of the soundfield;
wherein the first frequency range (HF) extends to higher frequencies than the second frequency range (MF) and a distance between the loudspeakers (903b, <NUM>; 903d, 903f) of the plurality of loudspeakers (903a-<NUM>) forming the first dipole (DH1, DH3) is smaller than a distance between the loudspeakers (903c, <NUM>) of the plurality of loudspeakers (903a-<NUM>) forming the second dipole (DH2).